@article {6301, title = {Grassland sensitivity to drought is related to functional composition across East Asia and North America}, journal = {Ecology}, year = {In Press}, keywords = {LTER-KNZ}, doi = {10.1002/ecy.4220}, url = {https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecy.4220}, author = {Song, Lin and Griffin-Nolan, Robert J. and Muraina, Taofeek O. and Chen, Jiaqi and Te, Niwu and Shi, Yuan and Whitney, Kenneth D. and Zhang, Bingchuan and Yu, Qiang and M. D. Smith and Zuo, Xiaoan and Wang, Zhengwen and Alan K. Knapp and Han, Xingguo and S.L Collins and Luo, Wentao} } @article {6266, title = {Nothing lasts forever: Dominant species decline under rapid environmental change in global grasslandsAbstract}, journal = {Journal of Ecology}, year = {In Press}, keywords = {LTER-KNZ}, doi = {10.1111/1365-2745.14198}, url = {https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2745.14198}, author = {Wilfahrt, Peter A. and Seabloom, Eric W. and Bakker, Jonathan D. and Biederman, Lori and Bugalho, Miguel N. and Cadotte, Marc W. and Caldeira, Maria C. and Catford, Jane A. and Chen, Qingqing and Donohue, Ian and Ebeling, Anne and Eisenhauer, Nico and Haider, Sylvia and Heckman, Robert W. and Jentsch, Anke and Koerner, S.E. and Komatsu, K.J. and Laungani, Ramesh and MacDougall, Andrew and Martina, Jason P. and Martinson, Holly and Moore, Joslin L. and Niu, Yujie and Ohlert, Timothy and Venterink, Harry Olde and Orr, Devyn and Peri, Pablo and Pos, Edwin and Price, Jodi and Raynaud, Xavier and Ren, Zhengwei and Roscher, Christiane and Smith, Nicholas G. and Stevens, Carly J. and Sullivan, Lauren L. and Tedder, Michelle and Tognetti, Pedro M. and Veen, Ciska and Wheeler, George and Young, Alyssa L. and Young, Hillary and Borer, Elizabeth T.} } @article {6294, title = {Extreme drought impacts have been underestimated in grasslands and shrublands globally}, journal = {Proceedings of the National Academy of Sciences}, volume = {121}, year = {2024}, pages = {e230988112}, keywords = {LTER-KNZ}, doi = {10.1073/pnas.2309881120}, url = {https://pnas.org/doi/10.1073/pnas.2309881120}, author = {M. D. Smith and Wilkins, Kate D. and Holdrege, Martin C. and Wilfahrt, Peter and S.L Collins and Knapp, Alan K. and Sala, Osvaldo E. and Dukes, Jeffrey S. and Phillips, Richard P. and Yahdjian, Laura and Gherardi, Laureano A. and Ohlert, Timothy and Beier, Claus and Fraser, Lauchlan H. and Jentsch, Anke and Loik, Michael E. and Maestre, Fernando T. and Power, Sally A. and Yu, Qiang and Felton, Andrew J. and Munson, Seth M. and Luo, Yiqi and Abdoli, Hamed and Abedi, Mehdi and Alados, Concepci{\'o}n L. and Alberti, Juan and Alon, Moshe and An, Hui and Anacker, Brian and Anderson, Maggie and Auge, Harald and Bachle, Seton and Bahalkeh, Khadijeh and Bahn, Michael and Batbaatar, Amgaa and Bauerle, Taryn and Beard, Karen H. and Behn, Kai and Beil, Ilka and Biancari, Lucio and Blindow, Irmgard and Bondaruk, Viviana Florencia and Borer, Elizabeth T. and Bork, Edward W. and Bruschetti, Carlos Martin and Byrne, Kerry M. and Cahill Jr., James F. and Calvo, Dianela A. and Carbognani, Michele and Cardoni, Augusto and Carlyle, Cameron N. and Castillo-Garcia, Miguel and Chang, Scott X. and Chieppa, Jeff and Cianciaruso, Marcus V. and Cohen, Ofer and Cordeiro, Amanda L. and Cusack, Daniela F. and Dahlke, Sven and Daleo, Pedro and D{\textquoteright}Antonio, Carla M. and Dietterich, Lee H. and S. Doherty, Tim and Dubbert, Maren and Ebeling, Anne and Eisenhauer, Nico and Fischer, Fel{\'\i}cia M. and Forte, T{\textquoteright}ai G. W. and Gebauer, Tobias and Gozalo, Beatriz and Greenville, Aaron C. and Guidoni-Martins, Karlo G. and Hannusch, Heather J. and Vats{\o} Haugum, Siri and Hautier, Yann and Hefting, Mariet and Henry, Hugh A. L. and Hoss, Daniela and Ingrisch, Johannes and Iribarne, Oscar and Isbell, Forest and Johnson, Yari and Jordan, Samuel and Kelly, Eugene F. and Kimmel, Kaitlin and Kreyling, Juergen and Kr{\"o}el-Dulay, Gy{\"o}rgy and Kr{\"o}pfl, Alicia and K{\"u}bert, Angelika and Kulmatiski, Andrew and Lamb, Eric G. and Larsen, Klaus Steenberg and Larson, Julie and Lawson, Jason and Leder, Cintia V. and Linst{\"a}dter, Anja and Liu, Jielin and Liu, Shirong and Lodge, Alexandra G. and Longo, Grisel and Loydi, Alejandro and Luan, Junwei and Curtis Lubbe, Frederick and Macfarlane, Craig and Mackie-Haas, Kathleen and Malyshev, Andrey V. and Maturano-Ruiz, {\'a}n and Merchant, Thomas and Metcalfe, Daniel B. and Mori, Akira S. and Mudongo, Edwin and Newman, Gregory S. and Nielsen, Uffe N. and Nimmo, Dale and Niu, Yujie and Nobre, Paola and O{\textquoteright}Connor, Rory C. and Ogaya, Rom{\`a} and O{\~n}atibia, Gast{\'o}n R. and Orb{\'a}n, Ildik{\'o} and Osborne, Brooke and Otfinowski, Rafael and P{\"a}rtel, Meelis and Pe{\~n}uelas, Josep and Peri, Pablo L. and Peter, Guadalupe and Petraglia, Alessandro and Picon-Cochard, Catherine and Pillar, Val{\'e}rio D. and Pi{\~N}Eiro-Guerra, Juan Manuel and Ploughe, Laura W. and Plowes, Robert M. and Portales-Reyes, Cristy and Prober, Suzanne M. and Pueyo, Yolanda and Reed, Sasha C. and Ritchie, Euan G. and Rodr{\'\i}guez, Ayl{\'e}n and Rogers, William E. and Roscher, Christiane and S{\'a}nchez, Ana M. and Santos, Br{\'a}ulio A. and Scarf{\'o}, Mar{\'\i}a and Seabloom, Eric W. and Shi, Baoku and Souza, Lara and Stampfli, Andreas and Standish, Rachel J. and Sternberg, Marcelo and Sun, Wei and S{\"u}nnemann, Marie and Tedder, Michelle and Thorvaldsen, {\r a}l and Tian, Dashuan and Tielb{\"o}rger, Katja and Valdecantos, Alejandro and van den Brink, Liesbeth and Vandvik, Vigdis and Vankoughnett, Mathew R. and Guri Velle, Liv and Wang, Changhui and Wang, Yi and Wardle, Glenda M. and Werner, Christiane and Wei, Cunzheng and Wiehl, Georg and Williams, Jennifer L. and Wolf, Amelia A. and Zeiter, Michaela and Zhang, Fawei and Zhu, Juntao and Zong, Ning and Zuo, Xiaoan} } @article {6238, title = {Compositional variation in grassland plant communities}, journal = {Ecosphere}, volume = {14}, year = {2023}, pages = {e4542}, keywords = {LTER-KNZ}, doi = {10.1002/ecs2.v14.610.1002/ecs2.4542}, url = {https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecs2.4542}, author = {Bakker, Jonathan D. and Price, Jodi N. and Henning, Jeremiah A. and Batzer, Evan E. and Ohlert, Timothy J. and Wainwright, Claire E. and Adler, Peter B. and Alberti, Juan and Arnillas, Carlos Alberto and Biederman, Lori A. and Borer, Elizabeth T. and Brudvig, Lars A. and Buckley, Yvonne M. and Bugalho, Miguel N. and Cadotte, Marc W. and Caldeira, Maria C. and Catford, Jane A. and Chen, Qingqing and Crawley, Michael J. and Daleo, Pedro and Dickman, Chris R. and Donohue, Ian and DuPre, Mary Ellyn and Ebeling, Anne and Eisenhauer, Nico and Fay, Philip A. and Gruner, Daniel S. and Haider, Sylvia and Hautier, Yann and Jentsch, Anke and Kirkman, Kevin and Knops, Johannes M. H. and Lannes, Lu{\'\i}ola S. and MacDougall, Andrew S. and McCulley, Rebecca L. and Mitchell, Rachel M. and Moore, Joslin L. and Morgan, John W. and Mortensen, Brent and Olde Venterink, Harry and Peri, Pablo L. and Power, Sally A. and Prober, Suzanne M. and Roscher, Christiane and Sankaran, Mahesh and Seabloom, Eric W. and M. D. Smith and Stevens, Carly and Sullivan, Lauren L. and Tedder, Michelle and Veen, G. F. (Ciska) and Virtanen, Risto and Wardle, Glenda M.} } @article {6267, title = {Diversity{\textendash}stability relationships across organism groups and ecosystem types become decoupled across spatial scales}, journal = {Ecology}, volume = {104}, year = {2023}, pages = {e4136}, keywords = {LTER-KNZ}, doi = {10.1002/ecy.v104.910.1002/ecy.4136}, url = {https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecy.4136}, author = {Wisnoski, Nathan I. and Andrade, Riley and Castorani, Max C. N. and Catano, Christopher P. and Compagnoni, Aldo and Lamy, Thomas and Lany, Nina K. and Marazzi, Luca and Record, Sydne and Smith, Annie C. and Swan, Christopher M. and Tonkin, Jonathan D. and Voelker, Nicole M. and Zarnetske, Phoebe L. and Sokol, Eric R.} } @article {6205, title = {Evolutionary lineage explains trait variation among 75 coexisting grass species}, journal = {New Phytologist}, volume = {239}, year = {2023}, pages = {887}, chapter = {875}, keywords = {LTER-KNZ}, doi = {10.1111/nph.18983}, url = {https://nph.onlinelibrary.wiley.com/doi/10.1111/nph.18983}, author = {Donnelly, R, and Wedel, E.R. and Taylor, J.H. and Nippert, J.B. and Helliker, B.R. and Riley, W. and Still, C.J. and Griffith, D.} } @article {6204, title = {Remotely sensed soil moisture can capture dynamics relevant to plant water uptake}, journal = {Water Resources Research}, volume = {59}, year = {2023}, pages = {e2022WR033814}, keywords = {LTER-KNZ}, doi = {10.1029/2022WR033814}, url = {https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022WR033814}, author = {Feldman, Andrew F. and Short Gianotti, Daniel J. and Dong, Jianzhi and Akbar, Ruzbeh and Crow, Wade T. and McColl, Kaighin A. and Konings, Alexandra G. and Nippert, J.B. and Tumber-D{\'a}vila, Shersingh Joseph and Holbrook, Noel M. and Rockwell, Fulton E. and Scott, Russell L. and Reichle, Rolf H. and Chatterjee, Abhishek and Joiner, Joanna and Poulter, Benjamin and Entekhabi, Dara} } @article {6177, title = {Trajectories and state changes of a grassland stream and riparian zone after a decade of woody vegetation removal}, journal = {Ecological Applications}, volume = {33}, year = {2023}, pages = {e2830}, keywords = {LTER-KNZ}, doi = {10.1002/eap.2830}, url = {https://onlinelibrary.wiley.com/doi/10.1002/eap.2830}, author = {Walter K. Dodds and Z. Ratajczak and Keen, Rachel M. and Nippert, J.B. and Grudzinski, Bartosz and Veach, Allison and Taylor, Jeffery H. and Kuhl, Amanda} } @article {6082, title = {Intra-canopy leaf trait variation facilitates high leaf area index and compensatory growth in a clonal woody-encroaching shrub}, journal = {Tree Physiology}, volume = {42}, year = {2022}, pages = {2186{\textendash}2202}, keywords = {LTER-KNZ}, doi = {10.1093/treephys/tpac078}, url = {https://academic.oup.com/treephys/advance-article/doi/10.1093/treephys/tpac078/6647984}, author = {Tooley, E. G. and Jesse B. Nippert and Bachle, Seton. and Keen, R.M.} } @article {6047, title = {Limited legacy effects of extreme multiyear drought on carbon and nitrogen cycling in a mesic grassland}, journal = {Elementa: Science of the Anthropocene}, volume = {10}, year = {2022}, pages = {000093}, abstract = {

The intensification of drought throughout the U.S. Great Plains has the potential to have large impacts on grassland functioning, as has been shown with dramatic losses of plant productivity annually. Yet, we have a poor understanding of how grassland functioning responds after drought ends. This study examined how belowground nutrient cycling responds after drought and whether legacy effects persist postdrought. We assessed the 2-year recovery of nutrient cycling processes following a 4-year experimental drought in a mesic grassland by comparing two different growing season drought treatments\—chronic (each rainfall event reduced by 66\%) and intense (all rain eliminated until 45\% of annual rainfall was achieved)\—to the control (ambient precipitation) treatment. At the beginning of the first growing season postdrought, we found that in situ soil CO2 efflux and laboratory-based soil microbial respiration were reduced by 42\% and 22\%, respectively, in the intense drought treatment compared to the control, but both measures had recovered by midseason (July) and remained similar to the control treatment in the second postdrought year. We also found that extractable soil ammonium and total inorganic N were elevated throughout the growing season in the first year after drought in the intense treatment. However, these differences in inorganic N pools did not persist during the growing season of the second year postdrought. The remaining measures of C and N cycling in both drought treatments showed no postdrought treatment effects. Thus, although we observed short-term legacy effects following the intense drought, C and N cycling returned to levels comparable to nondroughted grassland within a single growing season regardless of whether the drought was intense or chronic in nature. Overall, these results suggest that the key aspects of C and N cycling in mesic tallgrass prairie do not exhibit persistent legacies from 4 years of experimentally induced drought.

}, keywords = {LTER-KNZ}, doi = {10.1525/elementa.2021.000093}, url = {https://online.ucpress.edu/elementa/article/10/1/000093/122265/Limited-legacy-effects-of-extreme-multiyear}, author = {Vilonen, Leena L. and Blair, J.M. and Trivedi, Pankaj and L.H. Zeglin and M. D. Smith} } @article {6050, title = {N and P constrain C in ecosystems under climate change: role of nutrient redistribution, accumulation, and stoichiometry}, journal = {Ecological Applications}, volume = {32}, year = {2022}, pages = {e2684}, keywords = {LTER-KNZ}, doi = {10.1002/eap.2684}, url = {https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/eap.2684}, author = {Rastetter, E.B. and Kwiakowski, B.L. and Kicklighter, D.W. and Barker Plotkin, A. and Genet, H. and Jesse B. Nippert and O{\textquoteright}Keefe, K. and Perakis, S.R. and Porder, S. and Roley, S.S. and Reuss, R.W. and Thompson, J.R. and Wieder, W.R. and K.R. Wilcox and Yanai, R.D.} } @article {6112, title = {Nutrient enrichment increases invertebrate herbivory and pathogen damage in grasslands}, journal = {Journal of Ecology}, volume = {110}, year = {2022}, pages = {327 - 339}, keywords = {LTER-KNZ}, doi = {10.1111/1365-2745.13801}, url = {https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2745.13801}, author = {Ebeling, Anne and Strauss, Alex T. and Adler, Peter B. and Arnillas, Carlos A. and Barrio, ~C. and Biederman, Lori A. and Borer, Elizabeth T. and Bugalho, Miguel N. and Caldeira, ~C. and Cadotte, Marc W. and Daleo, Pedro and Eisenhauer, Nico and Eskelinen, Anu and Fay, Philip A. and Firn, Jennifer and Graff, Pamela and Hagenah, Nicole and Haider, Sylvia and Kimberly J. Komatsu and McCulley, ~L. and Mitchell, Charles E. and Moore, Joslin L. and Pascual, Jesus and Peri, Pablo L. and Power, Sally A. and Prober, Suzanne M. and Risch, ~C. and Roscher, Christiane and Sankaran, Mahesh and Seabloom, ~W. and Schielzeth, Holger and Sch{\"u}tz, Martin and Speziale, Karina L. and Tedder, Michelle and Virtanen, Risto and Blumenthal, Dana M.} } @article {6070, title = {Prairie stream metabolism recovery varies based on antecedent hydrology across a stream network after a bank-full flood}, journal = {Limnology and Oceanography}, volume = {67}, year = {2022}, pages = {1986-1999}, keywords = {LTER-KNZ}, doi = {10.1002/lno.12182}, url = {https://onlinelibrary.wiley.com/doi/10.1002/lno.12182}, author = {Ruffing, Claire M. and Veach, A.M. and Schechner, Anne and R{\"u}egg, Janine and Trentman, Matt T. and W. K. Dodds} } @article {6023, title = {Precipitation effects on nematode diversity and carbon footprint across grasslands}, journal = {Global Change Biology}, volume = {28}, year = {2022}, pages = {2124-2132}, keywords = {LTER-KNZ}, doi = {10.1111/gcb.16055}, url = {https://onlinelibrary.wiley.com/doi/10.1111/gcb.16055}, author = {Franco, Andr{\'e} L.C. and Guan, Pingting and Cui, Shuyan and Tomasel, Cecilia M. and Gherardi, Laureano A. and Sala, O.E. and Wall, Diana H.} } @article {6069, title = {Precipitation, not land use, primarily determines the composition of both plant and phyllosphere fungal communities}, journal = {Frontiers in Fungal Biology}, volume = {3}, year = {2022}, pages = {805225}, keywords = {LTER-KNZ}, doi = {10.3389/ffunb.2022.805225}, url = {https://www.frontiersin.org/articles/10.3389/ffunb.2022.805225/full}, author = {Dea, Hannah I. and Urban, Abigail and Kazarina, Anna and Houseman, Gregory R. and Thomas, Samantha G. and Loecke, Terry and Greer, Mitchell J. and Platt, Thomas G. and Lee, Sonny and A. Jumpponen} } @article {6081, title = {Reintroducing bison results in long-running and resilient increases in grassland diversity}, journal = {PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES}, volume = {119}, year = {2022}, pages = {e2210433119}, abstract = {

The widespread extirpation of megafauna may have destabilized ecosystems and altered biodiversity globally. Most megafauna extinctions occurred before the modern record, leaving it unclear how their loss impacts current biodiversity. We report the long-term effects of reintroducing plains bison (Bison bison) in a tallgrass prairie versus two land uses that commonly occur in many North American grasslands: 1) no grazing and 2) intensive growing-season grazing by domesticated cattle (Bos taurus). Compared to ungrazed areas, reintroducing bison increased native plant species richness by 103\% at local scales (10 m2) and 86\% at the catchment scale. Gains in richness continued for 29 y and were resilient to the most extreme drought in four decades. These gains are now among the largest recorded increases in species richness due to grazing in grasslands globally. Grazing by domestic cattle also increased native plant species richness, but by less than half as much as bison. This study indicates that some ecosystems maintain a latent potential for increased native plant species richness following the reintroduction of native herbivores, which was unmatched by domesticated grazers. Native-grazer gains in richness were resilient to an extreme drought, a pressure likely to become more common under future global environmental change.

}, keywords = {LTER-KNZ}, doi = {10.1073/pnas.2210433119}, url = {https://www.pnas.org/doi/10.1073/pnas.2210433119}, author = {Ratajczak, Z. and S.L Collins and J. M. Blair and Koerner, S.E. and Louthan, A.M. and M. D. Smith and Taylor, J.H. and Jesse B. Nippert} } @article {6051, title = {Root traits reveal safety and efficiency differences in grasses and shrubs exposed to different fire regimes}, journal = {Functional Ecology}, volume = {36}, year = {2022}, pages = {368 - 379}, keywords = {LTER-KNZ}, doi = {10.1111/fec.v36.210.1111/1365-2435.13972}, url = {https://onlinelibrary.wiley.com/toc/13652435/36/2}, author = {O{\textquoteright}Keefe, Kimberly and Bachle, Seton and Keen, Rachel and Tooley, E. Greg and Jesse B. Nippert} } @mastersthesis {6054, title = {The unique canopy structure, leaf morphology, and physiology of Cornus drummondii}, volume = {MS Thesis}, year = {2022}, school = {Kansas State University}, type = {M.S. Thesis}, address = {Manhattan, KS}, keywords = {LTER-KNZ}, url = {https://krex.k-state.edu/dspace/handle/2097/42162}, author = {Tooley, E. G} } @article {5968, title = {Determinants of community compositional change are equally affected by global change}, journal = {Ecology Letters}, volume = {24}, year = {2021}, pages = {1892-1904}, abstract = {

Global change is impacting plant community composition, but the mechanisms underlying these changes are unclear. Using a dataset of 58 global change experiments, we tested the five fundamental mechanisms of community change: changes in evenness and richness, reordering, species gains and losses. We found 71\% of communities were impacted by global change treatments, and 88\% of communities that were exposed to two or more global change drivers were impacted. Further, all mechanisms of change were equally likely to be affected by global change treatments\—species losses and changes in richness were just as common as species gains and reordering. We also found no evidence of a progression of community changes, for example, reordering and changes in evenness did not precede species gains and losses. We demonstrate that all processes underlying plant community composition changes are equally affected by treatments and often occur simultaneously, necessitating a wholistic approach to quantifying community changes.

}, keywords = {LTER-KNZ}, doi = {10.1111/ele.13824}, url = {https://onlinelibrary.wiley.com/doi/10.1111/ele.13824}, author = {M.L. Avolio and Kimberly J. Komatsu and S.L Collins and Grman, Emily and Koerner, S.E. and Tredennick, A.T. and Wilcox, K.R. and Baer, S.G. and E.H. Boughton and Britton, Andrea J. and Foster, Bryan and Gough, Laura and Hovenden, Mark and Isbell, Forest and Jentsch, Anke and Johnson, David S. and Knapp, Alan K. and Kreyling, Juergen and Langley, J. Adam and Lortie, Christopher and McCulley, Rebecca L. and McLaren, Jennie R. and Reich, Peter B. and Seabloom, Eric W. and Smith, Melinda D. and Suding, Katharine N. and Suttle, K. Blake and Tognetti, Pedro M.}, editor = {Anderson, Marti} } @article {5970, title = {Negative effects of nitrogen override positive effects of phosphorus on grassland legumes worldwide}, journal = {Proceedings of the National Academy of Sciences}, volume = {118}, year = {2021}, pages = {e2023718118}, keywords = {LTER-KNZ}, doi = {10.1073/pnas.2023718118}, url = {http://www.pnas.org/lookup/doi/10.1073/pnas.2023718118}, author = {Tognetti, Pedro M. and Prober, Suzanne M. and B{\'a}ez, Selene and Chaneton, Enrique J. and Firn, Jennifer and Risch, Anita C. and Schuetz, Martin and Simonsen, Anna K. and Yahdjian, Laura and Borer, Elizabeth T. and Seabloom, Eric W. and Arnillas, Carlos Alberto and Bakker, Jonathan D. and Brown, Cynthia S. and Cadotte, Marc W. and Caldeira, Maria C. and Daleo, Pedro and Dwyer, John M. and Fay, Philip A. and Gherardi, Laureano A. and Hagenah, Nicole and Hautier, Yann and Kimberly J. Komatsu and McCulley, Rebecca L. and Price, Jodi N. and Standish, Rachel J. and Stevens, Carly J. and Wragg, Peter D. and Sankaran, Mahesh} } @article {6002, title = {Precipitation manipulation and terrestrial carbon cycling: The roles of treatment magnitude, experimental duration and local climate}, journal = {Global Ecology and Biogeography}, volume = {30}, year = {2021}, pages = {1909 - 1921}, keywords = {LTER-KNZ}, doi = {10.1111/geb.13356}, url = {https://onlinelibrary.wiley.com/doi/10.1111/geb.13356?af=R}, author = {Wang, Jinsong and Tian, Dashuan and Alan K. Knapp and Chen, Han Y. H. and Luo, Yiqi and Li, Zhaolei and Hou, Enqing and Huang, Xinzhao and Jiang, Lifen and Niu, Shuli}, editor = {Michaletz, Sean} } @article {5969, title = {Is a prescribed fire sufficient to slow the spread of woody plants in an infrequently burned grassland? A case study in tallgrass prairie}, journal = {Rangeland Ecology \& Management}, volume = {78}, year = {2021}, pages = {79 - 89}, abstract = {

In many mesic grasslands, such as the central Great Plains in North America, frequent fire is a key regulator of ecological processes. Long periods of infrequent fire facilitate the conversion of herbaceous-dominated grassland to woody-dominated shrubland or woodland. At the Konza Prairie Biological Station in northeast Kansas, one infrequently burned portion of the landscape has undergone transformation from grassland to woodland after nearly 30 yr without fire. In Spring 2017, a prescribed burn was implemented to assess fire effectiveness on woody plant mortality. A postfire census of 3 000+ individual woody plants identified the distribution of species by size (height), topographic position, and slope on the landscape. Mortality and canopy fire damage were calculated for each individual. In lowland locations with near-continuous shrub cover (30.7\% of the landscape), woody plants were unaffected by fire. However, in upland and slope locations, where shrubs and trees were sparser, survival probability varied by topographic position and species. In these locations 68\% of all woody individuals experienced 90\% or greater fire damage to the canopy, with 56\% of these individuals exhibiting new canopy regrowth within 2 mo after the fire. The two most abundant woody shrubs, Cornus drummondii and Rhus aromatica, showed high survival at all height classes and landscape positions. The two abundant tree species, Gleditsia triacanthos and Juniperus virginiana, showed increased survival probability with tree height that varied by landscape position. Survival of J. virginiana also varied according to proximity and size of neighboring clonal shrubs, providing a mechanism for persistence of this fire-sensitive tree species even at small height classes. The probability survival curves developed here are useful for managers assessing when to prescribe fire to maximize mortality for J. virginiana and provide insight relevant for broader ecological understanding of woody encroachment within grasslands throughout the world.

}, keywords = {LTER-KNZ}, doi = {10.1016/j.rama.2021.05.007}, url = {https://linkinghub.elsevier.com/retrieve/pii/S1550742421000609}, author = {Nippert, J.B. and Telleria, Lizeth and Blackmore, Pamela and Taylor, Jeffrey H. and O{\textquoteright}Connor, Rory C.} } @article {5989, title = {RivFishTIME: A global database of fish time-series to study global change ecology in riverine systems}, journal = {Global Ecology and Biogeography}, volume = {30}, year = {2021}, pages = {38 - 50}, keywords = {LTER-KNZ}, doi = {10.1111/geb.13210}, url = {https://onlinelibrary.wiley.com/doi/epdf/10.1111/geb.13210}, author = {Comte, Lise and Carvajal, Juan and Tedesco, Pablo A. and Giam, Xingli and Brose, Ulrich and Er{\H o}s, Tibor and Filipe, Ana F. and Fortin, Marie-Jos{\'e}e and Irving, Katie and Jacquet, Claire and Larsen, Stefano and Sharma, Sapna and Ruhi, Albert and Becker, Fernando G. and Casatti, Lilian and Castaldelli, Giuseppe and Dala-Corte, Renato B. and Davenport, Stephen R. and Franssen, Nathan R. and Garc{\'\i}a-Berthou, Emili and Gavioli, Anna and K. B. Gido and Jimenez-Segura, Luz and Leit{\~a}o, Rafael P. and McLarney, Bill and Meador, Jason and Milardi, Marco and Moffatt, David B. and Occhi, Thiago V. T. and Pompeu, Paulo S. and Propst, David L. and Pyron, Mark and Salvador, Gilberto N. and Stefferud, Jerome A. and Sutela, Tapio and Taylor, Christopher and Terui, Akira and Urabe, Hirokazu and Vehanen, Teppo and Vitule, Jean R. S. and Zeni, Jaquelini O. and Olden, Julian D.}, editor = {Bahn, Volker} } @article {6123, title = {Seasonal changes in GPP/SIF ratios and their climatic determinants across the Northern Hemisphere}, journal = {Global Change Biology}, volume = {27}, year = {2021}, pages = {5186 - 5197}, keywords = {LTER-KNZ}, doi = {10.1111/gcb.15775}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.15775}, author = {Chen, Anping and Mao, Jiafu and Ricciuto, Daniel and Lu, Dan and Xiao, Jingfeng and Li, Xing and Thornton, Peter E. and Alan K. Knapp} } @article {6111, title = {Species loss due to nutrient addition increases with spatial scale in global grasslands}, journal = {Ecology Letters}, volume = {24}, year = {2021}, pages = {2100 - 2112}, abstract = {

The effects of altered nutrient supplies and herbivore density on species diversity vary with spatial scale, because coexistence mechanisms are scale dependent. This scale dependence may alter the shape of the species\–area relationship (SAR), which can be described by changes in species richness (S) as a power function of the sample area (A): S = cAz, where c and z are constants. We analysed the effects of experimental manipulations of nutrient supply and herbivore density on species richness across a range of scales (0.01\–75 m2) at 30 grasslands in 10 countries. We found that nutrient addition reduced the number of species that could co-occur locally, indicated by the SAR intercepts (log c), but did not affect the SAR slopes (z). As a result, proportional species loss due to nutrient enrichment was largely unchanged across sampling scales, whereas total species loss increased over threefold across our range of sampling scales.

}, keywords = {LTER-KNZ}, doi = {10.1111/ele.v24.1010.1111/ele.13838}, url = {https://onlinelibrary.wiley.com/doi/10.1111/ele.13838}, author = {Seabloom, Eric W. and Batzer, Evan and Chase, Jonathan M. and Stanley Harpole, W. and Adler, Peter B. and Bagchi, Sumanta and Bakker, Jonathan D. and Barrio, Isabel C. and Biederman, Lori and Boughton, Elizabeth H. and Bugalho, Miguel N. and Caldeira, Maria C. and Catford, Jane A. and Daleo, Pedro and Eisenhauer, Nico and Eskelinen, Anu and Haider, Sylvia and Hallett, Lauren M. and J{\'o}nsd{\'o}ttir, Ingibj{\"o}rg Svala and Kimmel, Kaitlin and Kuhlman, Marirose and MacDougall, Andrew and Molina, Cecilia D. and Moore, Joslin L. and Morgan, John W. and Muthukrishnan, Ranjan and Ohlert, Timothy and Risch, Anita C. and Roscher, Christiane and Sch{\"u}tz, Martin. and Sonnier, Gr{\'e}gory. and Tognetti, Pedro M. and Virtanen, Risto and Wilfahrt, Peter A. and Borer, Elizabeth T.}, editor = {Haddad, Nick} } @article {KNZ002049, title = {Synergies among environmental science research and monitoring networks: A research agenda}, journal = {Earth{\textquoteright}s Future}, volume = {9}, year = {2021}, pages = {e2020EF001631}, abstract = {

Many research and monitoring networks in recent decades have provided publicly available data documenting environmental and ecological change, but little is known about the status of efforts to synthesize this information across networks. We convened a working group to assess ongoing and potential cross-network synthesis research and outline opportunities and challenges for the future, focusing on the US-based research network (the US Long-Term Ecological Research network, LTER) and monitoring network (the National Ecological Observatory Network, NEON). LTER-NEON cross-network research synergies arise from the potentials for LTER measurements, experiments, models, and observational studies to provide context and mechanisms for interpreting NEON data, and for NEON measurements to provide standardization and broad scale coverage that complement LTER studies. Initial cross-network syntheses at co-located sites in the LTER and NEON networks are addressing six broad topics: how long-term vegetation change influences C fluxes; how detailed remotely sensed data reveal vegetation structure and function; aquatic-terrestrial connections of nutrient cycling; ecosystem response to soil biogeochemistry and microbial processes; population and species responses to environmental change; and disturbance, stability and resilience. This initial study offers exciting potentials for expanded cross-network syntheses involving multiple long-term ecosystem processes at regional or continental scales. These potential syntheses could provide a pathway for the broader scientific community, beyond LTER and NEON, to engage in cross-network science. These examples also apply to many other research and monitoring networks in the US and globally, and can guide scientists and research administrators in promoting broad-scale research that supports resource management and environmental policy.

}, keywords = {LTER-KNZ}, doi = {10.1029/2020EF001631}, url = {https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020EF001631}, author = {Jones, J.A. and Groffman, P.M. and Blair, J.M. and Davis, F.W. and Dugan, H. and Euskirchen, E.E. and Frey, S.D. and Harms, T.K. and Hinckley, E. and Kosmala, M. and Loberg, S. and Malone, S. and Novick, K. and Record, S. and Rocha, A.V. and Ruddell, B.L. and Stanley, E.H. and Sturtevant, C. and Thorpe, A. and White, T. and Wieder, W.R. and Zhai, L. and Zhu, K.} } @article {6115, title = {Temporal rarity is a better predictor of local extinction risk than spatial rarity}, journal = {Ecology}, volume = {102}, year = {2021}, keywords = {LTER-KNZ}, doi = {10.1002/ecy.3504}, url = {https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1002/ecy.3504}, author = {Wilfahrt, Peter A. and Asmus, Ashley L. and Seabloom, Eric W. and Henning, Jeremiah A. and Adler, Peter and Arnillas, Carlos A. and Bakker, Jonathan D. and Biederman, Lori and Brudvig, Lars A. and Cadotte, Marc and Daleo, Pedro and Eskelinen, Anu and Firn, Jennifer and Harpole, W. Stanley and Hautier, Yann and Kirkman, K.P. and Kimberly J. Komatsu and Laungani, Ramesh and MacDougall, Andrew and McCulley, Rebecca L. and Moore, Joslin L. and Morgan, John W. and Mortensen, Brent and Ochoa Hueso, Raul and Ohlert, Timothy and Power, Sally A. and Price, Jodi and Risch, Anita C. and Schuetz, Martin and Shoemaker, Lauren and Stevens, Carly and Strauss, Alexander T. and Tognetti, Pedro M. and Virtanen, Risto and Borer, Elizabeth T.} } @article {KNZ001993, title = {Biomass loss and change in species dominance shift stream community excretion stoichiometry during severe drought}, journal = {Freshwater Biology}, volume = {65}, year = {2020}, pages = {403-416}, abstract = {

\ \ \  1. Animals contribute significantly to nutrient cycling through excretion, but most studies consider their effects under relatively benign abiotic conditions. Disturbances such as drought may alter animals\’ nutrient contributions through shifts in species composition and biomass. Headwater streams are particularly vulnerable to extreme climate events and thus might show rapid changes in stream biota and their ecosystem effects.
\ \ \  2. We tested how biomass and subsequent ecosystem effects (nutrient cycling) of an intermittent prairie stream community changed during a drought. We quantified the biomass and contributions to nutrient cycling for assemblages comprising fishes, crayfish, and tadpoles in 12 isolated pools over 3 months encompassing the harshest drought on record for Kings Creek, KS, U.S.A. We predicted that macroconsumer biomass would decline with pool surface area and that differences in macroconsumer biomass and taxonomic composition would lead to different contributions of pool assemblages to nutrient cycling.
\ \ \  3. The biomass of pool assemblages declined with decreasing pool size, a pattern apparently driven by mortality, emigration, or metamorphosis. We also observed a change in assemblage structure of drying pools during drought relative to pool size, shifting dominance toward species with more drought-resistant traits. Accordingly, assemblage nitrogen (N) excretion rates declined as pool biomass was reduced, leading to a 58\% reduction in N available to epilithic biofilms. Phosphorus (P) excretion rates declined from June to July, but increased in August, as species with high P excretion rates maintained similar proportional biomass and biomass of a non-native fish increased. Molar N:P of pool assemblage excretion declined significantly throughout the drought and coincided with loss of southern redbelly dace (Chrosomus erythrogaster: Cyprinidae).
\ \ \  4. Animal-mediated nutrient cycling was altered by the loss of biomass and stoichiometric traits of taxa that differed in their occurrences and ability to tolerate abiotic conditions during drought. Elevated availability of dissolved N in isolated pools may increase N uptake rates by biofilms during drought conditions, indicating the importance of N excreted by aggregated macroconsumers, especially those with unique stoichiometric traits. While the significance of shifts in the composition of freshwater communities to ecosystems is not entirely known, additional losses in ecosystem function and changes in community structure may follow episodes of severe drought.

}, keywords = {LTER-KNZ}, doi = {10.1111/fwb.13433}, url = {https://onlinelibrary.wiley.com/doi/pdf/10.1111/fwb.13433}, author = {Hopper, Garrett W. and K. B. Gido and Pennock, Casey A. and Hedden, Skyler C. and Guinnip, James P. and Fisher, Molly A. and Tobler, Courtney M. and Hedden, Crosby K. and Lindsey A. Bruckerhoff} } @article {KNZ001997, title = {Browsing and fire decreases dominance of a resprouting shrub in woody encroached grassland}, journal = {Ecology}, volume = {101}, year = {2020}, pages = {e02935}, abstract = {

North American grasslands have experienced increased relative abundance of shrubs and trees over the last 150 years. Alterations in herbivore composition, abundance and grazing pressure along with changes in fire frequency are drivers that can regulate the transition from grassland to shrubland or woodland (a process known as woody encroachment). Historically, North American grasslands had a suite of large herbivores that grazed and/or browsed (i.e. bison, elk, pronghorn, deer), as well as frequent and intense fires. In the tallgrass prairie, many large native ungulates were extirpated by the 1860\’s corresponding with increased homesteading (which led to decreased fire frequencies and intensities). Changes in the frequency and intensity of these two drivers (browsing and fire) has coincided with woody encroachment in tallgrass prairie. Within tallgrass prairie, woody encroachment can be categorized in to two groups: non-resprouting species that can be killed with fire, and resprouting species that cannot be killed with fire. Resprouting species require additional active management strategies to decrease abundance and eventually be removed from the ecosystem. In this study we investigated plant cover, ramet density and physiological effects of continuous simulated browsing and prescribed fire on Cornus drummondii C.A. Mey, a resprouting clonal native shrub species. Browsing reduced C. drummondii canopy cover and increased grass cover. We also observed decreased ramet density that allowed for more infilling of grasses. Photosynthetic rates between browsed and unbrowsed control shrubs did not increase in 2015 or 2016. In 2017, photosynthetic rates for browsed shrubs were higher in the unburned site than the unbrowsed control shrubs at the end of the growing season. Additionally, after the prescribed fire, browsed shrubs had ~ 90\% decreased cover, ~50\% reduced ramet density, and grass cover increased by ~ 80\%. In the roots of browsed shrubs after the prescribed fire, non-structural carbohydrates (NSC) experienced a 2-fold reduction in glucose and a 3-fold reduction in both sucrose and starch. The combined effects of browsing and fire show strong potential as a successful management tool to decrease the abundance of clonal-resprouting woody plants in mesic grasslands and illustrate the potential significance of browsers as a key driver in this ecosystem.

}, keywords = {LTER-KNZ}, doi = {10.1002/ecy.2935}, url = {https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1002/ecy.2935}, author = {O{\textquoteright}Connor, R.C. and Taylor, J.H. and Jesse B. Nippert} } @article {KNZ002029, title = {Global impacts of fertilization and herbivore removal on soil net nitrogen mineralization are modulated by local climate and soil properties}, journal = {Global Change Biology}, volume = {26}, year = {2020}, abstract = {

Soil nitrogen (N) availability is critical for grassland functioning. However, human activities have increased the supply of biologically limiting nutrients, and changed the density and identity of mammalian herbivores. These anthropogenic changes may alter net soil N mineralization (soil net Nmin), that is, the net balance between N mineralization and immobilization, which could severely impact grassland structure and functioning. Yet, to date, little is known about how fertilization and herbivore removal individually, or jointly, affect soil net Nmin across a wide range of grasslands that vary in soil and climatic properties. Here we collected data from 22 grasslands on five continents, all part of a globally replicated experiment, to assess how fertilization and herbivore removal affected potential (laboratory-based) and realized (field-based) soil net Nmin. Herbivore removal in the absence of fertilization did not alter potential and realized soil net Nmin. However, fertilization alone and in combination with herbivore removal consistently increased potential soil net Nmin. Realized soil net Nmin, in contrast, significantly decreased in fertilized plots where herbivores were removed. Treatment effects on potential and realized soil net Nmin were contingent on site-specific soil and climatic properties. Fertilization effects on potential soil net Nmin were larger at sites with higher mean annual precipitation (MAP) and temperature of the wettest quarter (T.q.wet). Reciprocally, realized soil net Nmin declined most strongly with fertilization and herbivore removal at sites with lower MAP and higher T.q.wet. In summary, our findings show that anthropogenic nutrient enrichment, herbivore exclusion and alterations in future climatic conditions can negatively impact soil net Nmin across global grasslands under realistic field conditions. This is an important context-dependent knowledge for grassland management worldwide.

}, keywords = {LTER-KNZ}, doi = {10.1111/gcb.15308}, url = {https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.15308}, author = {Risch, Anita C. and Zimmermann, Stefan and Moser, Barbara and Sch{\"u}tz, Martin and Hagedorn, Frank and Firn, Jennifer and Fay, Philip A. and Adler, Peter B. and Biederman, Lori A. and J. M. Blair and Borer, Elizabeth T. and Broadbent, Arthur A. D. and Brown, Cynthia S. and Cadotte, Marc W. and Caldeira, Maria C. and Davies, Kendi F. and Virgilio, Augustina and Eisenhauer, Nico and Eskelinen, Anu and Knops, Johannes M. H. and MacDougall, Andrew S. and McCulley, Rebecca L. and Melbourne, Brett A. and Moore, Joslin L. and Power, Sally A. and Prober, Suzanne M. and Seabloom, Eric W. and Siebert, Julia and Silveira, Maria L. and Speziale, Karina L. and Stevens, Carly J. and Tognetti, Pedro M. and Virtanen, Risto and Yahdjian, Laura and Ochoa-Hueso, Raul} } @article {KNZ002007, title = {Plant{\textendash}microbial interactions facilitate grassland species coexistence at the community level}, journal = {Oikos}, volume = {129}, year = {2020}, pages = {533-543}, abstract = {

Interspecific competition and plant\–soil feedbacks are powerful drivers of plant community structure. However, across a range of edaphic conditions the interactive effects of these drivers on complex plant communities remain unclear. For example, plant\–soil feedback studies focus on soil trained by a single plant species. We developed a method to assess effects of plant\–microbial interactions (PMI) on a complex plant community. We established mesocosms with 13 grassland species, grown individually or together, in overgrazed or restored soil, with or without soil microbial inoculum collected from a productive and diverse native grassland. We assessed biomass production as influenced by edaphic conditions, interspecific competition and PMI. Furthermore, we assessed potential influences of interspecific competition and edaphic conditions on strength and direction of PMI. Our results indicate PMI drives negative growth responses for graminoids while forbs experience positive growth responses. Generally, interspecific competition did not alter the magnitude or direction of PMI-mediated growth responses. Edaphic conditions altered the influence of soil microbial communities on individual plant growth while PMI facilitated plant evenness. In plant community mesocosms, PMI-associated benefits were observed in overgrazed soil. However, interspecific competition overwhelmed plant growth benefits associated with soil microbial communities when plant communities were grown in restored soil. In mesocosms containing dominant grass species, interspecific competition had negative effects on species coexistence, but both positive and negative PMI partially counterbalanced this influence on plant species evenness. Understanding these mechanisms may improve our capacity to manage diverse and productive grasslands by enabling prediction of plant community composition following disturbance and subsequent restoration.

}, keywords = {LTER-KNZ}, issn = {0030-1299}, doi = {10.1111/oik.06609}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/oik.06609}, author = {Li, Jiahuan and Xie, Shu and G.T. Wilson and Cobb, Adam B. and Tang, Shiming and Guo, Lizhu and Wang, Kun and Deng, Bo} } @article {KNZ002014, title = {Rainfall-manipulation experiments as simulated by terrestrial biosphere models: where do we stand?}, journal = {Global Change Biology}, volume = {26}, year = {2020}, pages = {3336{\textendash}3355}, abstract = {

Changes in rainfall amounts and patterns have been observed and are expected to continue in the near future with potentially significant ecological and societal consequences. Modelling vegetation responses to changes in rainfall is thus crucial to project water and carbon cycles in the future. In this study, we present the results of a new model-data intercomparison project, where we tested the ability of ten terrestrial biosphere models to reproduce observed sensitivity of ecosystem productivity to rainfall changes at ten sites across the globe, in nine of which, rainfall exclusion and/or irrigation experiments had been performed.

The key results are:
(a) Inter-model variation is generally large and model agreement varies with time scales. In severely water limited sites, models only agree on the interannual variability of evapotranspiration and to a smaller extent gross primary productivity. In more mesic sites model agreement for both water and carbon fluxes is typically higher on fine (daily-monthly) time scales and reduces on longer (seasonal-annual) scales.
(b) Models on average overestimate the relationship between ecosystem productivity and mean rainfall amounts across sites (in space) and have a low capacity in reproducing the temporal (interannual) sensitivity of vegetation productivity to annual rainfall at a given site, even though observation uncertainty is comparable to inter-model variability.
(c) Most models reproduced the sign of the observed patterns in productivity changes in rainfall manipulation experiments but had a low capacity in reproducing the observed magnitude of productivity changes. Models better reproduced the observed productivity responses due to rainfall exclusion than addition.
(d) All models attribute ecosystem productivity changes to the intensity of vegetation stress and peak leaf area, whereas the impact of the change in growing season length is negligible. The relative contribution of the peak leaf area and vegetation stress intensity was highly variable among models.

}, keywords = {LTER-KNZ}, doi = {10.1111/gcb.15024}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.15024}, author = {Paschalis, Athanasios and Fatichi, Simone and Zscheischler, Jakob and Ciais, Philippe and Michael Bahn and Lena R. Boysen and Chang, Jinfeng and De Kauwe, Martin and Estiarte, Marc and Goll, Daniel and Hanson, Paul J. and Harper, Anna B. and Hou, Enqing and Kigel, Jaime and Alan K. Knapp and Larsen, Klaus Steenberg and Li, Wei and Lienert, Sebastian and Luo, Yiqi and Meir, Patrick and Nabel, Julia E.M.S. and Ogaya, Rom{\`a} and Parolari, Anthony J and Peng, Changhui and Pe{\~n}uelas, Josep and Pongratz, Julia and Rambal, Serge and Schmidt, Inger Kappel and Shi, Hao and Sternberg, Marcelo and Tian, Hanqin and Tschumi, Elisabeth and Ukkola, Anna and Vicca, Sara and Viovy, Nicolas and Wang, -Ping and Wang, Zhuonan and Williams, Karina and Wu, Donghai and Zhu, Qiuan} } @article {KNZ002036, title = {Temporal variability in production is not consistently affected by global change drivers across herbaceous-dominated ecosystems}, journal = {Oecologia}, volume = {194}, year = {2020}, pages = {735{\textendash}744}, keywords = {LTER-KNZ}, author = {Avolio, M.L. and Wilcox, K.R. and La Pierre, K.J. and Lemoine, N. and Bowman, W.D. and Collins, S.L. and Knapp, A.K. and Koerner, S.E. and Smith, M.D. and Baer, S.G. and Gross, K.L. and Isbell, F. and McLaren, J. and Reich, P.B. and Suding, K.N. and Suttle, K.B. and Tilman, D. and Xu, Z. and Yu, Q.} } @article {KNZ002033, title = {Terabase metagenome sequencing of grassland soil microbiomes}, journal = {Microbiology Resource Announcements}, volume = {9}, year = {2020}, pages = {00718-20}, keywords = {LTER-KNZ}, doi = {10.1128/MRA.00718-20}, url = {https://mra.asm.org/content/9/32/e00718-20.abstract}, author = {Nelson, W. and Anderson, L. and Wu, R. and McDermott, J. and Bell, S. and A. Jumpponen and Fansler, S. and Tyrrell, K. and Farris, Y. and Hofmockel, K. and Jansson, J.} } @article {KNZ002017, title = {Using path analysis to determine interacting effects of biotic and abiotic factors on patch-scale biogeochemical rates in a prairie stream}, journal = {Aquatic Sciences}, volume = {82}, year = {2020}, abstract = {

Biogeochemical rates within streams vary with ecosystem properties including the distribution of fishes. While many studies investigate the singular effect of fishes on ecosystem components, there is a limited understanding of how fish presence interacts with other ecosystem properties to affect ecosystem structure and function. Here, we used path analyses to elucidate direct and indirect effects of fish presence, and other ecosystem properties on ecosystem respiration (ER), gross primary production (GPP), and ammonium uptake. Experimental responses of fish removal on patch scale (300 cm2) benthic rates of ER, GPP, and ammonium uptake were measured at two sites in a prairie stream. The effect of fish was determined by comparing substrata from field exclosures with fish absent to substrata exposed to fish. Total path model-explained variance was greatest for ER (R2\ =\ 0.55) and least for ammonium uptake (R2\ =\ 0.36) and GPP (R2\ =\ 0.34). Fish decreased algal biomass and directly increased all biogeochemical rates. The relative importance of the different abiotic ecosystem properties varied by process; however, FBOM and substrata size were important for most rates. This study provides evidence for predominantly direct effects of fish on both stream structure and function in a prairie stream. Our results emphasize that interactions between biotic and abiotic factors should be considered when determining drivers of biogeochemical activity. We suggest that simple linear food webs that consist of top\–down or bottom\–up control are not always sufficient to describe animal effects on ecosystem rates.

}, keywords = {LTER-KNZ}, doi = {10.1007/s00027-020-0702-8}, url = {http://link.springer.com/10.1007/s00027-020-0702-8}, author = {Trentman, M.T. and W. K. Dodds and K. B. Gido and R{\"u}egg, J. and Ruffing, C.M.} } @article {KNZ001944, title = {Assessing precipitation, evapotranspiration, and NDVI as controls of U.S. Great Plains plant production}, journal = {Ecosphere}, volume = {10}, year = {2019}, pages = {e02889}, abstract = {

Productivity throughout the North American Great Plains grasslands is generally considered to be water limited, with the strength of this limitation increasing as precipitation decreases. We hypothesize that cumulative actual evapotranspiration water loss (AET) from April to July is the precipitation-related variable most correlated to aboveground net primary production (ANPP) in the U.S. Great Plains (GP). We tested this by evaluating the relationship of ANPP to AET, precipitation, and plant transpiration (Tr). We used multi-year ANPP data from five sites ranging from semiarid grasslands in Colorado and Wyoming to mesic grasslands in Nebraska and Kansas, mean annual NRCS ANPP, and satellite-derived normalized difference vegetation index (NDVI) data. Results from the five sites showed that cumulative April-to-July AET, precipitation, and Tr were well correlated (R2: 0.54\–0.70) to annual changes in ANPP for all but the wettest site. AET and Tr were better correlated to annual changes in ANPP compared to precipitation for the drier sites, and precipitation in August and September had little impact on productivity in drier sites. April-to-July cumulative precipitation was best correlated (R2 = 0.63) with interannual variability in ANPP in the most mesic site, while AET and Tr were poorly correlated with ANPP at this site. Cumulative growing season (May-to-September) NDVI (iNDVI) was strongly correlated with annual ANPP at the five sites (R2 = 0.90). Using iNDVI as a surrogate for ANPP, we found that county-level cumulative April\–July AET was more strongly correlated to ANPP than precipitation for more than 80\% of the GP counties, with precipitation tending to perform better in the eastern more mesic portion of the GP. Including the ratio of AET to potential evapotranspiration (PET) improved the correlation of AET to both iNDVI and mean county-level NRCS ANPP. Accounting for how different precipitation-related variables control ANPP (AET in drier portion, precipitation in wetter portion) provides opportunity to develop spatially explicit forecasting of ANPP across the GP for enhancing decision-making by land managers and use of grassland ANPP for biofuels.

}, keywords = {LTER-KNZ}, doi = {10.1002/ecs2.2889}, url = {https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecs2.2889}, author = {Chen, Maosi and Parton, William J. and Hartman, Melannie D. and Del Grosso, Stephen J. and Smith, William K. and Alan K. Knapp and Lutz, Susan and Derner, Justin D. and Tucker, Compton J. and Ojima, Dennis S. and Volesky, Jerry D. and Stephenson, Mitchell B. and Schacht, Walter H. and Gao, Wei} } @article {KNZ001948, title = {Building an integrated infrastructure for exploring biodiversity: field collections and archives of mammals and parasites}, journal = {Journal of Mammalogy}, volume = {100}, year = {2019}, pages = {382 - 393}, abstract = {

Museum specimens play an increasingly important role in predicting the outcomes and revealing the consequences of anthropogenically driven disruption of the biosphere. As ecological communities respond to ongoing environmental change, host\–parasite interactions are also altered. This shifting landscape of host\–parasite associations creates opportunities for colonization of different hosts and emergence of new pathogens, with implications for wildlife conservation and management, public health, and other societal concerns. Integrated archives that document and preserve mammal specimens along with their communities of associated parasites and ancillary data provide a powerful resource for investigating, anticipating, and mitigating the epidemiological, ecological, and evolutionary impacts of environmental perturbation. Mammalogists who collect and archive mammal specimens have a unique opportunity to expand the scope and impact of their field work by collecting the parasites that are associated with their study organisms. We encourage mammalogists to embrace an integrated and holistic sampling paradigm and advocate for this to become standard practice for museum-based collecting. To this end, we provide a detailed, field-tested protocol to give mammalogists the tools to collect and preserve host and parasite materials that are of high quality and suitable for a range of potential downstream analyses (e.g., genetic, morphological). Finally, we also encourage increased global cooperation across taxonomic disciplines to build an integrated series of baselines and snapshots of the changing biosphere.

}, keywords = {LTER-KNZ}, doi = {10.1093/jmammal/gyz048}, url = {https://academic.oup.com/jmammal/article/100/2/382/5436909}, author = {Galbreath, Kurt E and Hoberg, Eric P and Cook, Joseph A and Armi{\'e}n, Blas and Bell, Kayce C and Campbell, Mariel L and Dunnum, Jonathan L and Dursahinhan, Altangerel T and Eckerlin, Ralph P and Gardner, Scott L and Greiman, Stephen E and Henttonen, Heikki and Jim{\'e}nez, Agust{\'\i}n and Koehler, Anson V A and Nyamsuren, Batsaikhan and Tkach, Vasyl V and Torres-P{\'e}rez, Fernando and Tsvetkova, Albina and Hope, Andrew G} } @article {KNZ001943, title = {The combined effects of an extreme heatwave and wildfire on tallgrass prairie vegetation}, journal = {Journal of Vegetation Science}, volume = {30}, year = {2019}, pages = {687 - 697}, abstract = {

Questions: Climate extremes are predicted to become more common in many ecosystems. Climate extremes can promote and interact with disturbances, but the combined effects of climate extremes and disturbances have not been quantified in many ecosystems. In this study, we ask whether the dual impact of a climate extreme and concomitant disturbance (wildfire) has a greater affect than a climate extreme alone.
Location: Tallgrass prairie in the Konza Prairie Biological Station, northeastern Kansas, USA.
Methods: We quantified the response of a tallgrass prairie plant community to a 2-year climate extreme of low growing-season precipitation and high temperatures. In the first year of the climate extreme, a subset of plots was burned by a growing-season wildfire. This natural experiment allowed us to compare community responses to a climate extreme with and without wildfire.
Results: In plots exposed to the climate extreme but not wildfire, community structure, diversity, and composition showed minor to insignificant changes, such as a 20\% reduction in grass cover and a slight increase in species diversity. Plots exposed to both the climate extreme and wildfire underwent larger changes, including an 80\% reduction in grass cover, 50\% increase in forb cover, and increased plant diversity. Two years after the climate extreme, structural shifts in burned plots showed little sign of recovery, indicating a potentially lasting shift in plant community structure.
Conclusions: Our results suggest that community responses to climate extremes need to account for climate-related disturbances \— in this case, high temperatures, drought and wildfire. This response diverged from our expectation that heat, drought, and an additional fire would favor grasses. Although growing-season wildfires in tallgrass prairie have been rare in recent decades, they will likely become more common with climate change, potentially leading to changes in grassland structure.

}, keywords = {LTER-KNZ}, doi = {10.1111/jvs.12750}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/jvs.12750}, author = {Z. Ratajczak and Churchill, Amber C. and Ladwig, Laura M. and Taylor, Jeff H. and Scott. L. Collins} } @article {KNZ001930, title = {Fire, grazing and climate shape plant{\textendash}grasshopper interactions in a tallgrass prairie}, journal = {Functional Ecology}, volume = {33}, year = {2019}, pages = {735 - 745}, abstract = {

1. Species interactions are integral to ecological community function, and the \ \  \  structure of species interactions has repercussions for the consequences of species extinctions. Few studies\  have examined the role of environmental factors in controlling species interaction networks across time.
2. We examined variation in plant\–grasshopper network structural properties in response to three major grassland drivers: periodic fire, ungulate grazing and climate.
3. We sequenced a plant barcoding gene from extracted grasshopper gut contents to characterize diets of 26 grasshopper species. Resulting grasshopper species\’ diets were combined with long-term plant and grasshopper surveys to assemble plant\–grasshopper networks across 13\–19 years for six watersheds subjected to varying fire and grazing treatments.
4. Network modularity, generality and predicted grasshopper community robustness to plant species loss all increased in grazed watersheds. Temperature decreased predicted grasshopper community robustness to plant species loss.
5. Grasshopper communities were found to be vulnerable to climatic warming due to host plant loss. However, intermediate disturbance from ungulate grazers may maintain grasshopper diversity and buffer community robustness to species loss. Our results suggest that climate and disturbance shape the structure of ecological interaction networks and thus have many indirect effects on species persistence though direct effects on interaction partners.

}, keywords = {LTER-KNZ}, doi = {10.1111/1365-2435.13272}, url = {https://besjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1365-2435.13272}, author = {Welti, Ellen A. R. and Fan, Q. and Tetreault, H.M. and Ungerer, M.C. and John M. Blair and Anthony Joern} } @article {KNZ001964, title = {The freshwater biome gradient framework: predicting macroscale properties based on latitude, altitude, and precipitation}, journal = {Ecosphere}, volume = {10}, year = {2019}, pages = {e02786}, abstract = {

Understanding global ecological patterns and processes, from biogeochemical to biogeographical, requires broad-scale macrosystems context for comparing and contrasting ecosystems. Climate gradients (precipitation and temperature) and other continental-scale patterns shape freshwater environments due to their influences on terrestrial environments and their direct and indirect effects on the abiotic and biotic characteristics of lakes, streams, and wetlands. We combined literature review, analyses of open access data, and logical argument to assess abiotic and biotic characters of freshwater systems across gradients of latitude and elevation that drive precipitation, temperature, and other variability. We explored the predictive value of analyzing patterns in freshwater ecosystems at the global macrosystems scale. We found many patterns based on climate, particularly those dependent upon hydrologic characteristics and linked to characteristics of terrestrial biomes. For example, continental waters of dry areas will generally be widely dispersed and have higher probability of drying and network disconnection, greater temperatures, greater inorganic turbidity, greater salinity, and lower riparian canopy cover relative to areas with high precipitation. These factors will influence local community composition and ecosystem rates. Enough studies are now available at the continental or global scale to start to characterize patterns under a coherent conceptual framework, though considerable gaps exist in the tropics and less developed regions. We present illustrative global-scale trends of abiotic, biotic, and anthropogenic impacts in freshwater ecosystems across gradients of precipitation and temperature to further understanding of broad-scale trends and to aid prediction in the face of global change. We view freshwater systems as occurring across arrays of multiple gradients (including latitude, altitude, and precipitation) rather than areas with specific boundaries. While terrestrial biomes capture some variability along these gradients that influence freshwaters, other features such as, slope, geology, and historical glaciation also influence freshwaters. Our conceptual framework is not so much a single hypothesis as a way to logically characterize patterns in freshwaters at scales relevant to (1) evolutionary processes that give rise to freshwater biodiversity, (2) regulatory units that influence freshwater ecosystems, and (3) the current scope of anthropogenic impacts on freshwaters and the vital ecosystem services they provide.

}, keywords = {LTER-KNZ}, doi = {10.1002/ecs2.2786}, url = {https://onlinelibrary.wiley.com/toc/21508925/10/7}, author = {W. K. Dodds and Lindsey A. Bruckerhoff and Batzer, Darold and Schechner, Anne and Pennock, Casey and Renner, Elizabeth and Tromboni, Flavia and Bigham, Kari and Grieger, Samantha} } @article {KNZ001965, title = {Global change effects on plant communities are magnified by time and the number of global change factors imposed}, journal = {Proceedings of the National Academy of Sciences}, volume = {116}, year = {2019}, pages = {17867-17873}, abstract = {

Global change drivers (GCDs) are expected to alter community structure and consequently, the services that ecosystems provide. Yet, few experimental investigations have examined effects of GCDs on plant community structure across multiple ecosystem types, and those that do exist present conflicting patterns. In an unprecedented global synthesis of over 100 experiments that manipulated factors linked to GCDs, we show that herbaceous plant community responses depend on experimental manipulation length and number of factors manipulated. We found that plant communities are fairly resistant to experimentally manipulated GCDs in the short term (\<10 y). In contrast, long-term (\≥10 y) experiments show increasing community divergence of treatments from control conditions. Surprisingly, these community responses occurred with similar frequency across the GCD types manipulated in our database. However, community responses were more common when 3 or more GCDs were simultaneously manipulated, suggesting the emergence of additive or synergistic effects of multiple drivers, particularly over long time periods. In half of the cases, GCD manipulations caused a difference in community composition without a corresponding species richness difference, indicating that species reordering or replacement is an important mechanism of community responses to GCDs and should be given greater consideration when examining consequences of GCDs for the biodiversity\–ecosystem function relationship. Human activities are currently driving unparalleled global changes worldwide. Our analyses provide the most comprehensive evidence to date that these human activities may have widespread impacts on plant community composition globally, which will increase in frequency over time and be greater in areas where communities face multiple GCDs simultaneously.

}, keywords = {LTER-KNZ}, doi = {10.1073/pnas.1819027116}, url = {https://www.pnas.org/content/early/2019/08/14/1819027116}, author = {Kimberly J. Komatsu and M.L. Avolio and Lemoine, Nathan P. and Isbell, Forest and Grman, Emily and Houseman, Gregory R. and Koerner, Sally E. and Johnson, D.S. and K.R. Wilcox and Juha M. Alatalo and Anderson, J.P. and Aerts, R. and S.G. Baer and Baldwin, Andrew H. and Bates, J. and Beierkuhnlein, C. and Belote, R.T. and John M. Blair and Bloor, J.M.G. and Bohlen, P.J. and Edward W. Bork and Elizabeth H. Boughton and W.D. Bowman and Britton, Andrea J. and Cahill, James F. and Chaneton, Enrique J. and Chiariello, N.R. and Cheng, Jimin. and Scott. L. Collins and Cornelissen, J.H.C. and G. Du and Eskelinen, Anu and Firn, Jennifer and Foster, B. and Gough, L. and Gross, K. and Hallett, L.M. and Han, X. and Harmens, H. and Hovenden, M.J. and Jagerbrand, A. and Jentsch, A. and Kern, Christel and Klanderud, Kari and Alan K. Knapp and Kreyling, Juergen and Li, W. and Luo, Yiqi and McCulley, R.L. and McLaren, Jennie R. and Megonigal, Patrick and J.W. Morgan and Onipchenko, Vladimir and Pennings, S.C. and Prev{\'e}y, J.S. and Price, Jodi N. and P.B. Reich and Robinson, Clare H. and Russell, L.F. and Sala, O.E. and Seabloom, E.W. and M.D. Smith and Soudzilovskaia, Nadejda A. and Souza, Lara and K.N. Suding and Suttle, B.K. and Svejcar, T. and Tilman, David and Tognetti, P. and Turkington, R. and White, S. and Xu, Zhuwen and Yahdjian, L. and Yu, Q. and Zhang, Pengfei and Zhang, Yunhai} } @article {KNZ001933, title = {Global patterns and drivers of ecosystem functioning in rivers and riparian zones}, journal = {Science Advances}, volume = {5}, year = {2019}, pages = {eaav0486}, abstract = {

River ecosystems receive and process vast quantities of terrestrial organic carbon, the fate of which depends strongly on microbial activity. Variation in and controls of processing rates, however, are poorly characterized at the global scale. In response, we used a peer-sourced research network and a highly standardized carbon processing assay to conduct a global-scale field experiment in greater than 1000 river and riparian sites. We found that Earth\’s biomes have distinct carbon processing signatures. Slow processing is evident across latitudes, whereas rapid rates are restricted to lower latitudes. Both the mean rate and variability decline with latitude, suggesting temperature constraints toward the poles and greater roles for other environmental drivers (e.g., nutrient loading) toward the equator. These results and data set the stage for unprecedented \“next-generation biomonitoring\” by establishing baselines to help quantify environmental impacts to the functioning of ecosystems at a global scale.

}, keywords = {LTER-KNZ}, doi = {10.1126/sciadv.aav0486}, url = {http://advances.sciencemag.org/content/5/1/eaav0486}, author = {Tiegs, Scott D. and Costello, David M. and Isken, Mark W. and Woodward, Guy and McIntyre, Peter B. and Gessner, Mark O. and Chauvet, Eric and Griffiths, Natalie A. and Flecker, Alex S. and Acu{\~n}a, Vicenc and Albari{\~n}o, Ricardo and Allen, Daniel C. and Alonso, Cecilia and Andino, Patricio and Arango, Clay and Aroviita, Jukka and Barbosa, Marcus V. M. and Barmuta, Leon A. and Baxter, Colden V. and Bell, Thomas D. C. and Bellinger, Brent and Boyero, Luz and Brown, Lee E. and Bruder, Andreas and Bruesewitz, Denise A. and Burdon, Francis J. and Callisto, Marcos and Canhoto, Cristina and Capps, Krista A. and Castillo, Mar{\'\i}a M. and Clapcott, Joanne and Colas, Fanny and Col{\'o}n-Gaud, Checo and Cornut, Julien and Crespo-P{\'e}rez, Ver{\'o}nica and Cross, Wyatt F. and Culp, Joseph M. and Danger, Michael and Dangles, Olivier and de Eyto, Elvira and Derry, Alison M. and Villanueva, {\'\i}az and Douglas, Michael M. and Elosegi, Arturo and Encalada, Andrea C. and Entrekin, Sally and Espinosa, Rodrigo and Ethaiya, Diana and Ferreira, Ver{\'o}nica and Ferriol, Carmen and Flanagan, Kyla M. and Fleituch, Tadeusz and Follstad Shah, Jennifer J. and Frainer Barbosa, Andr{\'e} and Friberg, Nikolai and Frost, Paul C. and Garcia, Erica A. and Garc{\'\i}a Lago, Liliana and Garc{\'\i}a Soto, Pavel Ernesto and Ghate, Sudeep and Giling, Darren P. and Gilmer, Alan and {\c c}alves, Jos{\'e} Francisco and Gonzales, Rosario Karina and Graca, Manuel A. S. and Grace, Mike and Grossart, Hans-Peter and Guerrold, Francois and Gulis, Vlad and Hepp, Luiz U. and Higgins, Scott and Hishi, Takuo and Huddart, Joseph and Hudson, John and Imberger, Samantha and {\~n}iguez-Armijos, Carlos and Iwata, Tomoya and Janetski, David J. and Jennings, Eleanor and Kirkwood, Andrea E. and Koning, Aaron A. and Kosten, Sarian and Kuehn, Kevin A. and Laudon, Hjalmar and Leavitt, Peter R. and Lemes da Silva, Aurea L. and Leroux, Shawn J. and LeRoy, Carri J. and Lisi, Peter J. and MacKenzie, Richard and Marcarelli, Amy M. and Masese, Frank O. and McKie, Brendan G. and Oliveira Medeiros, Adriana and Meissner, Kristian and Mili{\v s}a, Marko and Mishra, Shailendra and Miyake, Yo and Moerke, Ashley and Mombrikotb, Shorok and Mooney, Rob and Moulton, Tim and Muotka, Timo and Negishi, Junjiro N. and Neres-Lima, Vinicius and Nieminen, Mika L. and Nimptsch, Jorge and Ondruch, Jakub and Paavola, Riku and Pardo, Isabel and Patrick, Christopher J. and Peeters, Edwin T. H. M. and Pozo, Jesus and Pringle, Catherine and Prussian, Aaron and Quenta, Estefania and Quesada, Antonio and Reid, Brian and Richardson, John S. and Rigosi, Anna and Rinc{\'o}n, Jos{\'e} and Risnoveanu, Geta and Robinson, Christopher T. and Rodr{\'\i}guez-Gallego, Lorena and Royer, Todd V. and Rusak, James A. and Santamans, Anna C. and Selmeczy, G{\'e}za B. and Simiyu, Gelas and Skuja, Agnija and Smykla, Jerzy and Sridhar, Kandikere R. and Sponseller, Ryan and Stoler, Aaron and Swan, Christopher M. and Szlag, David and Mello, Franco Teixeira-de and Tonkin, Jonathan D. and Uusheimo, Sari and Veach, Allison M. and Vilbaste, Sirje and Vought, Lena B. M. and Wang, Chiao-Ping and Webster, Jackson R. and Wilson, Paul B. and Woelfl, Stefan and Xenopoulos, Marguerite A. and Yates, Adam G. and Yoshimura, Chihiro and Yule, Catherine M. and Zhang, Yixin X. and Zwart, Jacob A.} } @article {KNZ001985, title = {Soil net nitrogen mineralisation across global grasslands}, journal = {Nature Communications}, volume = {10}, year = {2019}, abstract = {

Soil nitrogen mineralisation (Nmin), the conversion of organic into inorganic N, is important for productivity and nutrient cycling. The balance between mineralisation and immobilisation (net Nmin) varies with soil properties and climate. However, because most global-scale assessments of net Nmin are laboratory-based, its regulation under field-conditions and implications for real-world soil functioning remain uncertain. Here, we explore the drivers of realised (field) and potential (laboratory) soil net Nmin across 30 grasslands worldwide. We find that realised Nmin is largely explained by temperature of the wettest quarter, microbial biomass, clay content and bulk density. Potential Nmin only weakly correlates with realised Nmin, but contributes to explain realised net Nmin when combined with soil and climatic variables. We provide novel insights of global realised soil net Nmin and show that potential soil net Nmin data available in the literature could be parameterised with soil and climate data to better predict realised Nmin.

}, keywords = {LTER-KNZ}, doi = {10.1038/s41467-019-12948-2}, url = {http://www.nature.com/articles/s41467-019-12948-2}, author = {Risch, A.C. and Zimmermann, S. and Ochoa-Hueso, R. and sch{\"u}tz, M. and Frey, B. and Firn, J. L. and Fay, P. A. and Hagedorn, F. and E.T. Borer and Seabloom, E. W. and Harpole, W. S. and Knops, J. M. H. and McCulley, R. L. and Broadbent, A. A. D. and Stevens, C. J. and Silveira, M. L. and P. Adler and B{\'a}ez, S. and L.A. Biederman and John M. Blair and Brown, C. S. and Caldeira, M. C. and Scott. L. Collins and Daleo, P. and di Virgilio, A. and Ebeling, A. and Eisenhauer, N. and Esch, E. and Eskelinen, A. and Hagenah, N. and Hautier, Y. and Kirkman, K. P. and MacDougall, A. S. and Joslin L. Moore and Power, S. A. and Prober, S. M. and Roscher, C. and Sankaran, M. and Siebert, J. and Speziale, K. L. and Tognetti, P. M. and Virtanen, R. and Yahdjian, L. and Moser, B.} } @article {KNZ001987, title = {Temperature effects on performance and physiology of two prairie stream minnows}, journal = {Conservation Physiology}, volume = {7}, year = {2019}, pages = {coz063}, abstract = {

Earth\’s atmosphere has warmed by ~1\°C over the past century and continues to warm at an increasing rate. Effects of atmospheric warming are already visible in most major ecosystems and are evident across all levels of biological organization. Linking functional responses of individuals to temperature is critical for predicting responses of populations and communities to global climate change. The southern redbelly dace Chrosomus erythrogaster and the central stoneroller Campostoma anomalum are two minnows (Cyprinidae) that commonly occur in the Flint Hills region of the USA but show different patterns of occurrence, with dace largely occupying headwater reaches and stonerollers persisting in both headwater and intermediate-sized streams. We tested for differences between species in critical thermal maximum, energy metabolism, sustained swimming and activity over an ecologically relevant temperature gradient of acclimation temperatures. Typically, metrics increased with acclimation temperature for both species, although stoneroller activity decreased with temperature. We observed a significant interaction between species and temperature for critical thermal maxima, where stonerollers only had higher critical thermal maxima at the coldest temperature and at warm temperatures compared to the dace. We did not find evidence suggesting differences in the energy metabolism of dace and stonerollers. We detected interspecific differences in sustained swimming performance, with dace having higher swimming speed than stonerollers regardless of acclimation temperature. Finally, there was a significant interaction between temperature and species for activity; dace activity was higher at intermediate and warm temperatures compared to stonerollers. We observed subtle interspecific differences in how performance metrics responded to temperature that did not always align with observed patterns of distribution for these species. Thus, other ecological factors likely are important drivers of distributional patterns in these species.

}, keywords = {LTER-KNZ, Activity, fish, metabolism, swimming performance, Temperature, thermal limit}, doi = {10.1093/conphys/coz063}, url = {https://academic.oup.com/conphys/article-pdf/7/1/coz063/30337107/coz063.pdf}, author = {Frenette, Bryan D and Lindsey A. Bruckerhoff and Tobler, Michael and K. B. Gido}, editor = {Clark, Timothy} } @phdthesis {KNZ001988, title = {The thermal ecology of prairie stream fishes}, volume = {PhD Dissertation}, year = {2019}, school = {Kansas State University}, type = {Ph.D. Thesis}, address = {Manhattan, KS.}, keywords = {LTER-KNZ}, url = {https://krex.k-state.edu/dspace/handle/2097/39839}, author = {Frenette, Bryan} } @article {KNZ001898, title = {Ambient changes exceed treatment effects on plant species abundance in long-term global change experiments}, journal = {Glob Chang Biol}, volume = {24}, year = {2018}, pages = {5668 - 5679}, abstract = {

The responses of species to environmental changes will determine future community composition and ecosystem function. Many syntheses of global change experiments examine the magnitude of treatment effect sizes, but we lack an understanding of how plant responses to treatments compare to ongoing changes in the unmanipulated (ambient or background) system. We used a database of long-term global change studies manipulating CO2 , nutrients, water, and temperature to answer three questions: (a) How do changes in plant species abundance in ambient plots relate to those in treated plots? (b) How does the magnitude of ambient change in species-level abundance over time relate to responsiveness to global change treatments? (c) Does the direction of species-level responses to global change treatments differ from the direction of ambient change? We estimated temporal trends in plant abundance for 791 plant species in ambient and treated plots across 16 long-term global change experiments yielding 2,116 experiment-species-treatment combinations. Surprisingly, for most species (57\%) the magnitude of ambient change was greater than the magnitude of treatment effects. However, the direction of ambient change, whether a species was increasing or decreasing in abundance under ambient conditions, had no bearing on the direction of treatment effects. Although ambient communities are inherently dynamic, there is now widespread evidence that anthropogenic drivers are directionally altering plant communities in many ecosystems. Thus, global change treatment effects must be interpreted in the context of plant species trajectories that are likely driven by ongoing environmental changes.

}, keywords = {LTER-KNZ, elevated CO2, nitrogen, Phosphorus, plant community, Warming, water}, doi = {10.1111/gcb.14442}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.14442}, author = {Langley, A. and Chapman, S.K. and Kimberly J. La Pierre and M.L. Avolio and W.D. Bowman and Johnson, D. and Isbell, F. and K.R. Wilcox and Foster, B. and Hovenden, M. and Alan K. Knapp and Koerner, S.E. and Lortie, C. and Megonigal, J. and Newton, P. and Reich, B. and M.D. Smith and Suttle, B.K. and Tilman, D.} } @article {KNZ001863, title = {Asymmetric responses of primary productivity to altered precipitation simulated by ecosystem models across three long-term grassland sites}, journal = {Biogeosciences}, volume = {15}, year = {2018}, pages = {3421 - 3437}, abstract = {

Field measurements of aboveground net primary productivity (ANPP) in temperate grasslands suggest that both positive and negative asymmetric responses to changes in precipitation (P) may occur. Under normal range of precipitation variability, wet years typically result in ANPP gains being larger than ANPP declines in dry years (positive asymmetry), whereas increases in ANPP are lower in magnitude in extreme wet years compared to reductions during extreme drought (negative asymmetry). Whether the current generation of ecosystem models with a coupled carbon\–water system in grasslands are capable of simulating these asymmetric ANPP responses is an unresolved question. In this study, we evaluated the simulated responses of temperate grassland primary productivity to scenarios of altered precipitation with 14 ecosystem models at three sites: Shortgrass steppe (SGS), Konza Prairie (KNZ) and Stubai Valley meadow (STU), spanning a rainfall gradient from dry to moist. We found that (1)\ the spatial slopes derived from modeled primary productivity and precipitation across sites were steeper than the temporal slopes obtained from inter-annual variations, which was consistent with empirical data; (2)\ the asymmetry of the responses of modeled primary productivity under normal inter-annual precipitation variability differed among models, and the mean of the model ensemble suggested a negative asymmetry across the three sites, which was contrary to empirical evidence based on filed observations; (3)\ the mean sensitivity of modeled productivity to rainfall suggested greater negative response with reduced precipitation than positive response to an increased precipitation under extreme conditions at the three sites; and (4)\ gross primary productivity (GPP), net primary productivity (NPP), aboveground NPP (ANPP) and belowground NPP (BNPP) all showed concave-down nonlinear responses to altered precipitation in all the models, but with different curvatures and mean values. Our results indicated that most models overestimate the negative drought effects and/or underestimate the positive effects of increased precipitation on primary productivity under normal climate conditions, highlighting the need for improving eco-hydrological processes in those models in the future.

}, keywords = {LTER-KNZ}, doi = {10.5194/bg-15-3421-2018}, url = {https://www.biogeosciences.net/15/3421/2018/}, author = {Wu, Donghai and Ciais, Philippe and Viovy, Nicolas and Alan K. Knapp and K.R. Wilcox and Michael Bahn and M.D. Smith and Vicca, Sara and Fatichi, Simone and Zscheischler, Jakob and He, Yue and Li, Xiangyi and Ito, Akihiko and Arneth, Almut and Harper, Anna and Ukkola, Anna and Paschalis, Athanasios and Poulter, Benjamin and Peng, Changhui and Ricciuto, Daniel and Reinthaler, David and Chen, Guangsheng and Tian, Hanqin and Genet, {\'e}l{\`e}ne and Mao, Jiafu and Ingrisch, Johannes and Nabel, Julia E. S. M. and Pongratz, Julia and Lena R. Boysen and Kautz, Markus and Schmitt, Michael and Meir, Patrick and Zhu, Qiuan and R. Hasibeder and Sippel, Sebastian and Dangal, Shree R. S. and Sitch, Stephen and Shi, Xiaoying and Wang, Yingping and Luo, Yiqi and Liu, Yongwen and Piao, Shilong} } @article {KNZ001888, title = {Change in dominance determines herbivore effects on plant biodiversity}, journal = {Nature Ecology and Evolution}, volume = {2}, year = {2018}, pages = {1925-1932}, abstract = {

Herbivores alter plant biodiversity (species richness) in many of the world\’s ecosystems, but the magnitude and the direction of herbivore effects on biodiversity vary widely within and among ecosystems. One current theory predicts that herbivores enhance plant biodiversity at high productivity but have the opposite effect at low productivity. Yet, empirical support for the importance of site productivity as a mediator of these herbivore impacts is equivocal. Here, we synthesize data from 252 large-herbivore exclusion studies, spanning a 20-fold range in site productivity, to test an alternative hypothesis\—that herbivore-induced changes in the competitive environment determine the response of plant biodiversity to herbivory irrespective of productivity. Under this hypothesis, when herbivores reduce the abundance (biomass, cover) of dominant species (for example, because the dominant plant is palatable), additional resources become available to support new species, thereby increasing biodiversity. By contrast, if herbivores promote high dominance by increasing the abundance of herbivory-resistant, unpalatable species, then resource availability for other species decreases reducing biodiversity. We show that herbivore-induced change in dominance, independent of site productivity or precipitation (a proxy for productivity), is the best predictor of herbivore effects on biodiversity in grassland and savannah sites. Given that most herbaceous ecosystems are dominated by one or a few species, altering the competitive environment via herbivores or by other means may be an effective strategy for conserving biodiversity in grasslands and savannahs globally.

}, keywords = {LTER-KNZ}, doi = {https://doi.org/10.1038/s41559-018-0696-y}, url = {https://www.nature.com/articles/s41559-018-0696-y$\#$article-info}, author = {Koerner, S.E. and M.D. Smith and Burkepile, D.E. and N.P. Hanan and M.L. Avolio and Scott. L. Collins and Alan K. Knapp and N.P. Lemoine and E.J. Forrestel and S. Eby and D.I. Thompson and G. Aguado-Santacruz and J.P. Anderson and Anderson, M. and A. Angassa and S. Bagchi and E.S. Bakker and Bastin, Gary and L.E. Baur and K.H. Beard and E.A. Beever and P.J. Bohlen and Elizabeth H. Boughton and Canestro, Don and Cesa, Ariela and Chaneton, Enrique and Cheng, Jimin and C.M. D{\textquoteright}Antonio and C. Deleglise and Fadiala. Demb{\'e}l{\'e} and Josh. Dorrough and David. J. Eldridge and Barbara. Fernandez-Going and Silvia. Fern{\'a}ndez-Lugo and Lauchlan. H. Fraser and Bill. Freedman and Gonzalo. Garc{\'\i}a-Salgado and Jacob. R. Goheen and Liang. Guo and Sean. Husheer and Moussa. Karemb{\'e} and Johannes. M. H. Knops and Tineke. Kraaij and Andrew. Kulmatiski and Minna-Maarit. Kyt{\"o}viita and Felipe. Lezama and Gregory. Loucougaray and Alejandro. Loydi, Dan G. Milchunas, and Dan.G. Milchunas, and Suzanne. J. Milton and J.W. Morgan and Claire. Moxham and Kyle. C. Nehring and Han. Olff and Todd. M. Palmer and Salvador. Rebollo and Corinna. Riginos and Anita. C. Risch and Marta Rueda and Mahesh. Sankaran and Takehiro. Sasaki and Kathryn. A. Schoenecker and Nick. L. Schultz and Martin. Sch{\"u}tz and Angelika. Schwabe and Frances. Siebert and Christian. Smit and Karen. A. Stahlheber and Christian. Storm and Dustin. J. Strong and Jishuai. Su and Yadugiri. V. Tiruvaimozhi and Claudia. Tyler and James. Val and Martijn. L. Vandegehuchte and Kari. E. Veblen and Lance. T. Vermeire and David. Ward and Jianshuang. Wu and Truman. P. Young and Qiang. Yu and Tamara. Jane. Zelikova} } @article {KNZ001918, title = {Continental-scale decrease in net primary productivity in streams due to climate warming}, journal = {Nature Geoscience}, volume = {11}, year = {2018}, pages = {415 - 420}, abstract = {

Streams play a key role in the global carbon cycle. The balance between carbon intake through photosynthesis and carbon release via respiration influences carbon emissions from streams and depends on temperature. However, the lack of a comprehensive analysis of the temperature sensitivity of the metabolic balance in inland waters across latitudes and local climate conditions hinders an accurate projection of carbon emissions in a warmer future. Here, we use a model of diel dissolved oxygen dynamics, combined with high-frequency measurements of dissolved oxygen, light and temperature, to estimate the temperature sensitivities of gross primary production and ecosystem respiration in streams across six biomes, from the tropics to the arctic tundra. We find that the change in metabolic balance, that is, the ratio of gross primary production to ecosystem respiration, is a function of stream temperature and current metabolic balance. Applying this relationship to the global compilation of stream metabolism data, we find that a 1\ \°C increase in stream temperature leads to a convergence of metabolic balance and to a 23.6\% overall decline in net ecosystem productivity across the streams studied. We suggest that if the relationship holds for similarly sized streams around the globe, the warming-induced shifts in metabolic balance will result in an increase of 0.0194\ Pg carbon emitted from such streams every year.

}, keywords = {LTER-KNZ}, doi = {10.1038/s41561-018-0125-5}, url = {http://www.nature.com/articles/s41561-018-0125-5}, author = {Song, Chao and W. K. Dodds and R{\"u}egg, Janine and Argerich, Alba and Baker, Christina L. and W.B. Bowden and Douglas, Michael M. and Farrell, Kaitlin J. and Flinn, Michael B. and Garcia, Erica A. and Helton, Ashley M. and Harms, Tamara K. and Jia, Shufang and Jones, Jeremy B. and Koenig, Lauren E. and Kominoski, John S. and McDowell, William H. and McMaster, Damien and Parker, Samuel P. and Rosemond, Amy D. and Ruffing, Claire M. and Sheehan, Ken R. and Trentman, Matt T. and M.R. Whiles and Wollheim, Wilfred M. and Ballantyne, Ford} } @article {KNZ001929, title = {The impact of long-term regional air mass patterns on nutrient precipitation chemistry and nutrient deposition within a United States grassland ecosystem}, journal = {Journal of Atmospheric Chemistry}, volume = {75}, year = {2018}, pages = {399-410}, abstract = {

Changes in the frequency of precipitation as a result of a changing climate, as well as anthropogenic induced deposition of nitrogen (N), both have the potential to alter grassland productivity and diversity. Central U.S. weather patterns are dominated by three major air mass trajectories including regional sources from the Gulf of Mexico (marine tropical, Mt), the Pacific Northwest (mild pacific, mP), and the Desert Southwest (continental tropical, Ct). In this work, the Hybrid Single Particle Lagrangian Integrated Trajectory model was used to determine trends in the proportion of precipitation events from these air mass sources from 1983 to 2006 relative to Konza Prairie Biological Station (KPBS), KS. The annual volume-weighted mean (VWM) concentrations and wet deposition of a variety of precipitation dissolved solutes were linked to source regions north or south of KPBS. The proportion of precipitation events from Mt significantly increased, while the proportion of events from Ct and mP decreased significantly over the study period. The annual VWM concentrations of most solutes were typically higher from precipitation sourced to the north of KPBS. However, wet deposition of four ecologically relevant solutes (NH4+, NO3\−, H+, and SO4\−2) was higher from events from the southern region, likely due to higher precipitation amounts. The proportion of reduced N increased significantly over the study period but was not affected by source region despite the higher use of fertilizers for agriculture in the northern source region. Given the location of this site relative to three dominant air mass paths, future shifts in these patterns will likely impact wet nutrient deposition.

}, keywords = {LTER-KNZ}, doi = {10.1007/s10874-018-9384-1}, url = {http://link.springer.com/10.1007/s10874-018-9384-1}, author = {Trentman, Matt T.} } @article {KNZ001891, title = {Microbial community structure and functional potential in cultivated and native tallgrass prairie soils of the midwestern united states}, journal = {Frontiers in Microbiology}, volume = {9}, year = {2018}, pages = {1775}, abstract = {

The North American prairie covered about 3.6 million-km2 of the continent prior to European contact. Only 1\–2\% of the original prairie remains, but the soils that developed under these prairies are some of the most productive and fertile in the world, containing over 35\% of the soil carbon in the continental United States. Cultivation may alter microbial diversity and composition, influencing the metabolism of carbon, nitrogen, and other elements. Here, we explored the structure and functional potential of the soil microbiome in paired cultivated-corn (at the time of sampling) and never-cultivated native prairie soils across a three-states transect (Wisconsin, Iowa, and Kansas) using metagenomic and 16S rRNA gene sequencing and lipid analysis. At the Wisconsin site, we also sampled adjacent restored prairie and switchgrass plots. We found that agricultural practices drove differences in community composition and diversity across the transect. Microbial biomass in prairie samples was twice that of cultivated soils, but alpha diversity was higher with cultivation. Metagenome analyses revealed denitrification and starch degradation genes were abundant across all soils, as were core genes involved in response to osmotic stress, resource transport, and environmental sensing. Together, these data indicate that cultivation shifted the microbiome in consistent ways across different regions of the prairie, but also suggest that many functions are resilient to changes caused by land management practices \– perhaps reflecting adaptations to conditions common to tallgrass prairie soils in the region (e.g., soil type, parent material, development under grasses, temperature and rainfall patterns, and annual freeze-thaw cycles). These findings are important for understanding the long-term consequences of land management practices to prairie soil microbial communities and their genetic potential to carry out key functions.

}, keywords = {LTER-KNZ, carbon cycle, Climate change, Land management, metagenomics, native prairie, nitrogen cycle, soil microbiome}, doi = {10.3389/fmicb.2018.01775}, url = {https://www.frontiersin.org/articles/10.3389/fmicb.2018.01775}, author = {Mackelprang, Rachel and Grube, Alyssa M. and Lamendella, Regina and Jesus, Ederson da C. and Copeland, Alex and Liang, Chao and Jackson, Randall D. and C. W. Rice and Kapucija, Stefanie and Parsa, Bayan and Tringe, Susannah G. and Tiedje, James M. and Jansson, Janet K.} } @article {KNZ001822, title = {Partitioning assimilatory nitrogen uptake in streams: an analysis of stable isotope tracer additions across continents}, journal = {Ecological Monographs}, volume = {88}, year = {2018}, pages = {138}, chapter = {120}, abstract = {

Headwater streams remove, transform, and store inorganic nitrogen (N) delivered from surrounding watersheds, but excessive N inputs from human activity can saturate removal capacity. Most research has focused on quantifying N removal from the water column over short periods and in individual reaches, and these ecosystem-scale measurements suggest that assimilatory N uptake accounts for most N removal. However, cross-system comparisons addressing the relative role of particular biota responsible for incorporating inorganic N into biomass are lacking. Here we assess the importance of different primary uptake compartments on reach-scale ammonium (NH4+-N) uptake and storage across a wide range of streams varying in abundance of biota and local environmental factors. We analyzed data from 17\ 15N-NH4+tracer addition experiments globally, and found that assimilatory N uptake by autotrophic compartments (i.e., epilithic biofilm, filamentous algae, bryophytes/macrophytes) was higher but more variable than for heterotrophic microorganisms colonizing detrital organic matter (i.e., leaves, small wood, and fine particles). Autotrophic compartments played a disproportionate role in N uptake relative to their biomass, although uptake rates were similar when we rescaled heterotrophic assimilatory N uptake associated only with live microbial biomass. Assimilatory NH4+-N uptake, either estimated as removal from the water column or from the sum uptake of all individual compartments, was four times higher in open- than in closed-canopy streams. Using Bayesian Model Averaging, we found that canopy cover and gross primary production (GPP) controlled autotrophic assimilatory N uptake while ecosystem respiration (ER) was more important for the heterotrophic contribution. The ratio of autotrophic to heterotrophic N storage was positively correlated with metabolism (GPP: ER), which was also higher in open- than in closed-canopy streams. Our analysis shows riparian canopy cover influences the relative abundance of different biotic uptake compartments and thus GPP:ER. As such, the simple categorical variable of canopy cover explained differences in assimilatory N uptake among streams at the reach scale, as well as the relative roles of autotrophs and heterotrophs in N storage. Finally, this synthesis links cumulative N uptake by stream biota to reach-scale N demand and provides a mechanistic and predictive framework for estimating and modeling N cycling in other streams.

}, keywords = {LTER-KNZ}, doi = {10.1002/ecm.1280}, url = {https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/ecm.1280}, author = {Tank, J.L. and Marti, E. and Riis, T. and von Schiller, D. and Reisinger, A.J. and W. K. Dodds and M.R. Whiles and L.R. Ashkenas and W.B. Bowden and S. M. Collins and Crenshaw, C.L. and Crowl, T.A. and Griffiths, N.A. and Grimm, N.B. and Hamilton, S.K. and Johnson, S.L. and McDowell, W.H. and Norman, B.M. and Rosi, E.J. and Simon, K.S. and Thomas, S.A. and Webster, J.R.} } @article {KNZ001897, title = {Scaling biodiversity responses to hydrological regimes}, journal = {Biological Reviews}, volume = {93}, year = {2018}, pages = {971 - 995}, abstract = {

Of all ecosystems, freshwaters support the most dynamic and highly concentrated biodiversity on Earth. These attributes of freshwater biodiversity along with increasing demand for water mean that these systems serve as significant models to understand drivers of global biodiversity change. Freshwater biodiversity changes are often attributed to hydrological alteration by water-resource development and climate change owing to the role of the hydrological regime of rivers, wetlands and floodplains affecting patterns of biodiversity. However, a major gap remains in conceptualising how the hydrological regime determines patterns in biodiversity\&$\#$39;s multiple spatial components and facets (taxonomic, functional and phylogenetic). We synthesised primary evidence of freshwater biodiversity responses to natural hydrological regimes to determine how distinct ecohydrological mechanisms affect freshwater biodiversity at local, landscape and regional spatial scales. Hydrological connectivity influences local and landscape biodiversity, yet responses vary depending on spatial scale. Biodiversity at local scales is generally positively associated with increasing connectivity whereas landscape-scale biodiversity is greater with increasing fragmentation among locations. The effects of hydrological disturbance on freshwater biodiversity are variable at separate spatial scales and depend on disturbance frequency and history and organism characteristics. The role of hydrology in determining habitat for freshwater biodiversity also depends on spatial scaling. At local scales, persistence, stability and size of habitat each contribute to patterns of freshwater biodiversity yet the responses are variable across the organism groups that constitute overall freshwater biodiversity. We present a conceptual model to unite the effects of different ecohydrological mechanisms on freshwater biodiversity across spatial scales, and develop four principles for applying a multi-scaled understanding of freshwater biodiversity responses to hydrological regimes. The protection and restoration of freshwater biodiversity is both a fundamental justification and a central goal of environmental water allocation worldwide. Clearer integration of concepts of spatial scaling in the context of understanding impacts of hydrological regimes on biodiversity will increase uptake of evidence into environmental flow implementation, identify suitable biodiversity targets responsive to hydrological change or restoration, and identify and manage risks of environmental flows contributing to biodiversity decline.

}, keywords = {LTER-KNZ}, doi = {10.1111/brv.12381}, url = {https://doi.org/10.1111/brv.12381}, author = {Rolls, Robert J. and Heino, Jani and Ryder, Darren S. and Chessman, Bruce C. and Growns, Ivor O. and Thompson, Ross M. and K. B. Gido} } @article {KNZ001864, title = {Similarity of stream width distributions across headwater systems}, journal = {Nature Communications}, volume = {9}, year = {2018}, chapter = {610}, abstract = {

The morphology and abundance of streams control the rates of hydraulic and biogeochemical exchange between streams, groundwater, and the atmosphere. In large river systems, the relationship between river width and abundance is fractal, such that narrow rivers are proportionally more common than wider rivers. However, in headwater systems, where many biogeochemical reactions are most rapid, the relationship between stream width and abundance is unknown. To constrain this uncertainty, we surveyed stream hydromorphology (wetted width and length) in several headwater stream networks across North America and New Zealand. Here, we find a strikingly consistent lognormal statistical distribution of stream width, including a characteristic most abundant stream width of 32\ \±\ 7\ cm independent of discharge or physiographic conditions. We propose a hydromorphic model that can be used to more accurately estimate the hydromorphology of streams, with significant impact on the understanding of the hydraulic, ecological, and biogeochemical functions of stream networks.

}, keywords = {LTER-KNZ}, doi = {10.1038/s41467-018-02991-w}, url = {https://www.nature.com/articles/s41467-018-02991-w}, author = {Allen, George H. and Pavelsky, Tamlin M. and Barefoot, Eric A. and Lamb, Michael P. and Butman, David and Tashie, Arik and Gleason, Colin J.} } @article {KNZ001851, title = {Top - down effects of a grazing, omnivorous minnow (Campostoma anomalum) on stream microbial communities}, journal = {Freshwater Science}, volume = {37}, year = {2018}, pages = {121-133}, abstract = {

Top\–down control exerted by macroconsumers can strongly affect lower trophic levels and ecosystem processes. Studies of effects on primary consumers in streams have been focused on algae, and effects on bacteria are largely unknown. We manipulated the density of an omnivorous, grazing minnow, the central stoneroller (Campostoma anomalum), in experimental stream mesocosms (treatments with 0, 1, 2, 3, 4, 5, 6, or 7 individuals) to understand consumer effects on algal and bacterial abundance (chlorophyll a [Chl a] extraction, bacterial cell counts, biomass measurements) and bacterial diversity and community composition (via Illumina MiSeq sequencing of the V4 region of the 16S ribosomal RNA gene). Increasing C. anomalum density reduced algal biomass until density reached ~2 fish (5 g fish biomass/m2), and higher fish densities did not affect algal biomass. Fish biomass did not affect bacterial cell counts. Biofilm organic matter decreased with increasing C. anomalum biomass. Bacterial community composition was not affected by fish biomass, but variation in community composition was correlated with shifts in bacterial abundances. Evenness of bacterial operational taxonomic units (OTUs) decreased with increasing C. anomalum biomass, indicating that bacterial communities exhibited a greater degree of OTU dominance when fish biomass was higher. These findings suggest that this grazing fish species reduces algal abundance and organic matter in low-nutrient streams until a threshold of moderate fish abundance is reached and that it reduces evenness of benthic bacterial communities but not bacterial biomass. Given the importance of biofilm bacteria for ecosystem processes and the ubiquity of grazing fishes in streams, future researchers should explore both top\–down and bottom\–up interactions in alternative environmental contexts and with other grazing fish species.

}, keywords = {LTER-KNZ}, doi = {10.1086/696292}, url = {https://www.journals.uchicago.edu/doi/abs/10.1086/696292}, author = {Veach, Allison M. and Troia, Matthew J. and A. Jumpponen and W. K. Dodds} } @article {KNZ001883, title = {Trait selection and community weighting are key to understanding ecosystem responses to changing precipitation regimes}, journal = {Functional Ecology}, volume = {32}, year = {2018}, pages = {1746 - 1756}, abstract = {

1. Plant traits can be used to predict ecosystem responses to environmental change using a response\–effect trait framework. To do this, appropriate traits must be identified that explain a species\&$\#$39; influence on ecosystem function (\“effect traits\”) and the response of those species to environmental change (\“response traits\”). Response traits are often identified and measured along gradients in plant resources, such as water availability; however, precipitation explains very little variation in most plant traits globally. Given the strong relationship between plant traits and ecosystem functions, such as net primary productivity (NPP), and between NPP and precipitation, the lack of correlation between precipitation and plant traits is surprising.

2. We address this issue through a systematic review of \>500 published studies that describe plant trait responses to altered water availability. The overarching goal of this review was to identify potential causes for the weak relationship between commonly measured plant traits and water availability so that we may identify more appropriate \“response traits.\”

3. We attribute weak trait\–precipitation relationships to an improper selection of traits (e.g., nonhydraulic traits) and a lack of trait-based approaches that adjust for trait variation within communities (only 4\% of studies measure community-weighted traits). We then highlight the mechanistic value of hydraulic traits as more appropriate \“response traits\” with regard to precipitation, which should be included in future community-scale trait surveys.

4. Trait-based ecology has the potential to improve predictions of ecosystem responses to predicted changes in precipitation; however, this predictive power depends heavily on the identification of reliable response and effect traits. To this end, trait surveys could be improved by a selection of traits that reflect physiological functions directly related to water availability with traits weighted by species relative abundance.

}, keywords = {LTER-KNZ}, doi = {10.1111/1365-2435.13135}, url = {https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2435.13135}, author = {Griffin-Nolan, Robert J. and Bushey, Julie A. and Carroll, Charles J. W. and Challis, Anthea and Chieppa, Jeff and Garbowski, Magda and Hoffman, Ava M. and Post, Alison K. and Slette, Ingrid J. and Spitzer, Daniel and Zambonini, Dario and Ocheltree, Troy W. and Tissue, David T. and Alan K. Knapp}, editor = {Fox, Charles} } @article {KNZ001852, title = {Assessing community and ecosystem sensitivity to climate change - toward a more comparative approach}, journal = {Journal of Vegetation Science}, volume = {28}, year = {2017}, pages = {235 - 237}, abstract = {

Plant communities can vary widely in their sensitivity to changing precipitation regimes, as reported by Byrne et al., Mulhouse et al. and Sternberg et al. in this issue of Journal of Vegetation Science. But to understand why communities differ in their sensitivity, we argue that clearly defined metrics of sensitivity and coordinated research approaches are needed to elucidate mechanisms.

}, keywords = {LTER-KNZ}, doi = {10.1111/jvs.12524}, url = {https://onlinelibrary.wiley.com/doi/full/10.1111/jvs.12524}, author = {M.D. Smith and K.R. Wilcox and Power, Sally A. and Tissue, David T. and Alan K. Knapp} } @article {KNZ001842, title = {Asynchrony among local communities stabilises ecosystem function of metacommunities}, journal = {Ecology Letters}, year = {2017}, abstract = {

Temporal stability of ecosystem functioning increases the predictability and reliability of ecosystem services, and understanding the drivers of stability across spatial scales is important for land management and policy decisions. We used species-level abundance data from 62 plant communities across five continents to assess mechanisms of temporal stability across spatial scales. We assessed how asynchrony (i.e. different units responding dissimilarly through time) of species and local communities stabilised metacommunity ecosystem function. Asynchrony of species increased stability of local communities, and asynchrony among local communities enhanced metacommunity stability by a wide range of magnitudes (1\–315\%); this range was positively correlated with the size of the metacommunity. Additionally, asynchronous responses among local communities were linked with species\’ populations fluctuating asynchronously across space, perhaps stemming from physical and/or competitive differences among local communities. Accordingly, we suggest spatial heterogeneity should be a major focus for maintaining the stability of ecosystem services at larger spatial scales.

}, keywords = {LTER-KNZ, Alpha diversity, alpha variability, beta diversity, Biodiversity, CoRRE data base, patchiness, Plant communities, Primary productivity, species synchrony}, doi = {10.1111/ele.12861}, url = {http://onlinelibrary.wiley.com/doi/10.1111/ele.12861/epdf}, author = {K.R. Wilcox and Tredennick, Andrew T. and Koerner, Sally E. and Grman, Emily and Hallett, Lauren M. and M.L. Avolio and Kimberly J. La Pierre and Houseman, Gregory R. and Isbell, Forest and Johnson, David Samuel and Juha M. Alatalo and Baldwin, Andrew H. and Edward W. Bork and Elizabeth H. Boughton and W.D. Bowman and Britton, Andrea J. and Cahill, James F. and Scott. L. Collins and G. Du and Eskelinen, Anu and Gough, Laura and Jentsch, Anke and Kern, Christel and Klanderud, Kari and Alan K. Knapp and Kreyling, Juergen and Luo, Yiqi and McLaren, Jennie R. and Megonigal, Patrick and Onipchenko, Vladimir and Prev{\'e}y, Janet and Price, Jodi N. and Robinson, Clare H. and Sala, Osvaldo E. and M.D. Smith and Soudzilovskaia, Nadejda A. and Souza, Lara and Tilman, David and White, Shannon R. and Xu, Zhuwen and Yahdjian, Laura and Yu, Qiang and Zhang, Pengfei and Zhang, Yunhai}, editor = {Gurevitch, Jessica} } @book {KNZ001833, title = {The biota of intermittent rivers and ephemeral streams: prokaryotes, fungi, and protozoans}, series = {Intermittent Rivers and Ephemeral Streams Ecology and Management}, year = {2017}, pages = {161 - 188}, publisher = {Elsevier}, organization = {Elsevier}, keywords = {LTER-KNZ}, doi = {10.1016/B978-0-12-803835-2.00009-7}, url = {https://www.sciencedirect.com/science/article/pii/B9780128038352000097?via\%3Dihub}, author = {Roman{\'\i}, Anna M. and Chauvet, Eric and Febria, Catherine and Mora-G{\'o}mez, Juanita and Risse-Buhl, Ute and Timoner, Xisca and Weitere, Markus and Lydia H. Zeglin} } @article {KNZ001847, title = {Different clades and traits yield similar grassland functional responses}, journal = {Proceedings of the National Academy of Sciences}, volume = {114}, year = {2017}, pages = {705 - 710}, abstract = {Plant functional traits are viewed as key to predicting important ecosystem and community properties across resource gradients within and among biogeographic regions. Vegetation dynamics and ecosystem processes, such as aboveground net primary productivity (ANPP), are increasingly being modeled as a function of the quantitative traits of species, which are used as proxies for photosynthetic rates and nutrient and water-use efficiency. These approaches rely on an assumption that a certain trait value consistently confers a specific function or response under given environmental conditions. Here, we provide a critical test of this idea and evaluate whether the functional traits that drive the well-known relationship between precipitation and ANPP differ between systems with distinct biogeographic histories and species assemblages. Specifically, we compared grasslands spanning a broad precipitation gradient (\~{}200{\textendash}1,000 mm/y) in North America and South Africa that differ in the relative representation and abundance of grass phylogenetic lineages. We found no significant difference between the regions in the positive relationship between annual precipitation and ANPP, yet the trait values underlying this relationship differed dramatically. Our results challenge the trait-based approach to predicting ecosystem function by demonstrating that different combinations of functional traits can act to maximize ANPP in a given environmental setting. Further, we show the importance of incorporating biogeographic and phylogenetic history in predicting community and ecosystem properties using traits. }, keywords = {LTER-KNZ, biogeography, Ecosystem function, Functional traits, grasslands. phylogenetics}, issn = {0027-8424}, doi = {10.1073/pnas.1612909114}, url = {https://www.pnas.org/content/114/4/705}, author = {Forrestel, Elisabeth J. and M.J. Donoghue and Edwards, Erika J. and Jetz, Walter and du Toit, Justin C. O. and M.D. Smith} } @article {KNZ001824, title = {Drivers of nitrogen transfer in stream food webs across continents}, journal = {Ecology}, volume = {98}, year = {2017}, pages = {3055}, chapter = {3044}, abstract = {

Studies of trophic-level material and energy transfers are central to ecology.\ The use of isotopic tracers has now made it possible to measure trophic transfer efficiencies of important nutrients and to better understand how these materials move through food webs.\ We analyzed data from thirteen\ 15N-ammonium tracer addition experiments to quantify N transfer from basal resources to animals in headwater streams with varying physical, chemical, and biological features. N transfer efficiencies from primary uptake compartments (PUCs; heterotrophic microorganisms and primary producers) to primary consumers was lower (mean 11.5\%, range \<1\% to 43\%) than N transfer efficiencies from primary consumers to predators (mean 80\%, range 5\% to \>100\%). Total N transferred (as a rate) was greater in streams with open compared to closed canopies and overall N transfer efficiency generally followed a similar pattern, although was not statistically significant. We used principal component analysis to condense a suite of site characteristics into two environmental components. Total N uptake rates among trophic levels were best predicted by the component that was correlated with latitude, DIN:SRP, GPP:ER, and percent canopy cover. N transfer efficiency did not respond consistently to environmental variables. Our results suggest that canopy cover influences N movement through stream food webs because light availability and primary production facilitate N transfer to higher trophic levels.

}, keywords = {LTER-KNZ}, doi = {10.1002/ecy.2009}, url = {https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1002/ecy.2009}, author = {Norman, B. C. and Whiles, M. R. and S. M. Collins and Flecker, A. S. and Hamilton, S. K. and Johnson, S. L. and Rosi-Marshall, E. J. and L.R. Ashkenas and W.B. Bowden and Crenshaw, C. L. and Crowl, T. and W. K. Dodds and Hall, R. O. and El-Sabaawi, R. and Griffiths, N. A. and Marti, E. and McDowell, W. H. and Peterson, S. D. and Rantala, H. M. and Riis, T. and Simon, K. S. and Tank, J. L. and Thomas, S. A. and von Schiller, D. and Webster, J. R.} } @article {KNZ001814, title = {How do extra nutrients affect the timing of flowering in prairies}, journal = {Environmental Science Journal for Teens}, year = {2017}, keywords = {LTER-KNZ}, url = {http://www.sciencejournalforkids.org/uploads/5/4/2/8/54289603/flowers_article.pdf}, author = {L.A. Biederman and Mortensen, Brent and Fay, P.A. and Hagenah, Nicole and Knops, Johannes and Kimberly J. La Pierre and Laungani, Ramesh and Lind, Eric and McCulley, Rebecca and Power, Sally and Seabloom, Eric and Tognetti, Pedro} } @article {KNZ001815, title = {Juniper invasions in grasslands: research needs and intervention strategies}, journal = {Rangelands}, volume = {39}, year = {2017}, pages = {64 - 72}, abstract = {{\textbullet} Despite prescribed fire programs, invasive juniper trees are increasing in the Great Plains. {\textbullet} Continued encroachment of junipers in the Great Plains, especially eastern redcedar and Ashe{\textquoteright}s juniper, is degrading grasslands and increasing health concerns through pollen production. {\textbullet} Biological and ecological research needs include effects on soil and water as well as restoration potential after a mature invasion is treated. {\textbullet} The interface of social science, ecology, economics, and policy may yield productive approaches to slowing the invasion.}, keywords = {LTER-KNZ}, doi = {10.1016/j.rala.2017.03.002}, url = {https://www.sciencedirect.com/science/article/pii/S0190052817300159?via\%3Dihub}, author = {Leis, Sherry A. and Blocksome, Carol E. and Twidwell, Dirac and Fuhlendorf, Sam D. and J. M. Briggs and Sanders, Larry D.} } @article {KNZ001803, title = {A long-term study of burning effects on a plant pathogen in tallgrass prairie}, journal = {Plant Pathology}, volume = {66}, year = {2017}, pages = {1308{\textendash}1317}, abstract = {Tallgrass prairie species have evolved with regular exposure to fire. Yet burning has been used as a management tool for reducing plant disease in agricultural systems, posing the question of how plant pathogens of tallgrass prairie will be affected by burning. We studied the rust fungus Puccinia dioicae infecting Erigeron strigosus (Asteraceae) for eight years in long-term experiments to evaluate burning effects in native tallgrass prairie. This experiment also allowed evaluation of the effects of nutrient additions, although E. strigosus was rare in the nutrient addition plots in most years. Burning reduced rust severity in most years. Effects of nutrient additions were rarely observed. There was high inter-annual variation in rust severity within a location, suggesting that weather may be the most important of these three abiotic factors in determining infection. An analysis of weather variables associated with disease severity found that solar radiation in the month prior to sampling was associated with severity in unburned plots; temperature approximately two months prior to sampling was associated with severity in burned plots. High inter-annual variation also suggests that the effects of this pathogen on its host would be sporadic and difficult to study in short-term experiments.}, keywords = {LTER-KNZ}, doi = {10.1111/ppa.12678}, url = {https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1002/ecm.1249}, author = {Dendy, S. P. and Tong, B. and Alexander, H. A. and Fay, P. A. and Murray, L. and Xing, Y. and Garrett, K. A.} } @article {KNZ001868, title = {Nutrient addition shifts plant community composition towards earlier flowering species in some prairie ecoregions in the U.S. Central Plains}, journal = {PLOS ONE}, year = {2017}, pages = {e0178440}, abstract = {

The distribution of flowering across the growing season is governed by each species\’ evolutionary history and climatic variability. However, global change factors, such as eutrophication and invasion, can alter plant community composition and thus change the distribution of flowering across the growing season. We examined three ecoregions (tall-, mixed, and short-grass prairie) across the U.S. Central Plains to determine how nutrient (nitrogen (N), phosphorus, and potassium (+micronutrient)) addition alters the temporal patterns of plant flowering traits. We calculated total community flowering potential (FP) by distributing peak-season plant cover values across the growing season, allocating each species\’ cover to only those months in which it typically flowers. We also generated separate FP profiles for exotic and native species and functional group. We compared the ability of the added nutrients to shift the distribution of these FP profiles (total and sub-groups) across the growing season. In all ecoregions, N increased the relative cover of both exotic species and C3 graminoids that flower in May through August. The cover of C4 graminoids decreased with added N, but the response varied by ecoregion and month. However, these functional changes only aggregated to shift the entire community\’s FP profile in the tall-grass prairie, where the relative cover of plants expected to flower in May and June increased and those that flower in September and October decreased with added N. The relatively low native cover in May and June may leave this ecoregion vulnerable to disturbance-induced invasion by exotic species that occupy this temporal niche. There was no change in the FP profile of the mixed and short-grass prairies with N addition as increased abundance of exotic species and C3 graminoids replaced other species that flower at the same time. In these communities a disturbance other than nutrient addition may be required to disrupt phenological patterns.

}, keywords = {LTER-KNZ}, doi = {10.1371/journal.pone.0178440}, url = {http://dx.plos.org/10.1371/journal.pone.0178440ttp}, author = {L.A. Biederman and Mortensen, B. and Fay, P.A. and Hagenah, N. and Knops, J. and Kimberly J. La Pierre and Laungani, R. and Lind, E. and McCulley, R. and Power, S. and Seabloom, E. and Tognetti, P.} } @article {KNZ001893, title = {Out of the shadows: multiple nutrient limitations drive relationships among biomass, light and plant diversity}, journal = {Functional Ecology}, volume = {31}, year = {2017}, pages = {1839-1846}, abstract = {
  1. The paradigmatic hypothesis for the effect of fertilisation on plant diversity represents a one-dimensional trade-off for plants competing for below-ground nutrients (generically) and above-ground light: fertilisation reduces competition for nutrients while increasing biomass and thereby shifts competition for depleted available light.
  2. The essential problem of this simple paradigm is that it misses both the multivariate and mechanistic nature of the factors that determine biodiversity as well as their causal relationships.
  3. We agree that light limitation, as DeMalach and Kadmon argue, can indeed be an important factor associated with diversity loss, and we presented it as an integral part of our tests of the niche dimension hypothesis.
  4. We disagree with DeMalach and Kadmon that light is the \‘main\’ factor explaining diversity, because this misrepresents the causal structure represented in the design of our experiment in which multiple nutrient addition was the ultimate causal driver of a suite of correlated responses that included diversity and light, and especially live and dead biomass, which are the factors that control light depletion.
  5. Our findings highlight that multiple nutrient limitations can structure plant diversity and composition independently of changes in light and biomass. For example, approximately one-third of our sites showed no significant increase in biomass with greater number of added nutrients yet still lost diversity when nutrients were added.
  6. The important message is that while light limitation can be an important contributor to diversity loss, it is not a necessary mechanism.
}, keywords = {LTER-KNZ}, doi = {10.1111/1365-2435.12967}, url = {https://besjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1365-2435.12967}, author = {Harpole, W. Stanley and L.L. Sullivan and Lind, Eric M. and Firn, Jennifer and P. Adler and E.T. Borer and Chase, Jonathan and Fay, Philip A. and Hautier, Yann and Hillebrand, Helmut and MacDougall, Andrew S. and Seabloom, Eric W. and Bakker, Jonathan D. and Cadotte, Marc W. and Chaneton, Enrique J. and Chu, Chengjin and Hagenah, Nicole and Kirkman, Kevin and Kimberly J. La Pierre and Joslin L. Moore and J.W. Morgan and Prober, Suzanne M. and Risch, Anita C. and Schuetz, Martin and Stevens, Carly J.}, editor = {Thompson, Ken} } @article {KNZ001896, title = {Testing metabolic cold adaptation as a driver of warm-water fish species replacement along the river continuum}, journal = {Environmental Biology of Fishes}, volume = {100}, year = {2017}, pages = {265-279}, abstract = {

Hydrologic and thermal regimes vary along the upstream-to-downstream river continuum and drive the assembly of fish communities. The metabolic cold adaptation (MCA) hypothesis predicts that faster development is adaptive for species exposed to shorter growing seasons. Whether gradients of hydrologic variability and seasonal thermal regime associated with the river continuum operate as environmental filters on species with differing developmental rates remains an untested mechanism of community assembly. We analyzed daily records of stream discharge and modeled stream temperatures to quantify these two gradients of abiotic harshness in Kansas, USA. We then used laboratory experiments to compare temperature-dependent larval development rates among three congeneric cyprinid species that are most abundant in small tributaries (Pimephales promelas), medium tributaries (P. notatus), or river mainstems (P. vigilax). Growing season duration increased with stream size, with temperature exceedance thresholds of 22 and 26\ \°C lasting 1.4 and 270 times longer, respectively, in eighth order river mainstems compared to second order tributaries. The frequency of small flood pulses within the growing season peaked in mid-order streams, whereas the frequency of large flood pulses within the growing season peaked in low-order streams. Larval development rates increased with incubation temperature, but did not differ predictably among species. These findings, when viewed alongside a companion study, suggest that thermal adaptation and not MCA explains the replacements of Pimephales species along the river continuum. The prominent upstream-to-downstream gradient in growing season duration highlights the need for studies on the evolutionary and ecological significance of this infrequently explored characteristic of the river continuum.

}, keywords = {LTER-KNZ}, doi = {10.1007/s10641-017-0577-2}, url = {http://link.springer.com/10.1007/s10641-017-0577-2}, author = {Troia, Matthew J. and K. B. Gido} } @article {KNZ001708, title = {Baseflow physical characteristics differ at multiple spatial scales in stream networks across diverse biomes}, journal = {Landscape Ecology}, volume = {31}, year = {2016}, pages = {119-136}, abstract = {

Context Spatial scaling of ecological processes is facilitated by quantifying underlying habitat attributes. Physical and ecological patterns are often measured at disparate spatial scales limiting our ability to quantify ecological processes at broader spatial scales using physical attributes. Objective We characterized variation of physical stream attributes during periods of high biological activity (i.e., baseflow) to match physical and ecological measurements and to identify the spatial scales exhibiting and predicting heterogeneity. Methods We measured canopy cover, wetted width, water depth, and sediment size along transects of 1st\–5th order reaches in five stream networks located in biomes from tropical forest to arctic tundra. We used hierarchical analysis of variance with three nested scales (watersheds, stream orders, reaches) to identify scales exhibiting significant heterogeneity in attributes and regression analyses to characterize gradients within and across stream networks. Results Heterogeneity was evident at one or multiple spatial scales: canopy cover and water depth varied significantly at all three spatial scales while wetted width varied at two scales (stream order and reach) and sediment size remained largely unexplained. Similarly, prediction by drainage area depended on the attribute considered: depending on the watershed, increases in wetted width and water depth with drainage area were best fit with a linear, logarithmic, or power function. Variation in sediment size was independent of drainage area. Conclusions The scaling of ecologically relevant baseflow physical characteristics will require study beyond the traditional bankfull geomorphology since predictions of baseflow physical attributes by drainage area were not always best explained by geomorphic power laws.

}, keywords = {LTER-KNZ, Boreal forest, Geomorphology, Grasslands, Nested ANOVA, Scaling, Temperate forest}, issn = {0921-2973}, doi = {10.1007/s10980-015-0289-y}, url = {https://link.springer.com/article/10.1007\%2Fs10980-015-0289-y}, author = {R{\"u}egg, Janine and W. K. Dodds and Daniels, M.D. and Sheehan, Ken R. and Baker, Christina L. and W.B. Bowden and Farrell, Kaitlin J. and Flinn, Michael B. and Harms, Tamara K. and Jones, J.B. and Koenig, Lauren E. and Kominoski, John S. and W.H. McDowell and Parker, Samuel P. and Rosemond, Amy D. and Trentman, Matt T. and M.R. Whiles and Wollheim, Wilfred M.} } @article {KNZ001765, title = {A before-and-after assessment of patch-burn grazing and riparian fencing along headwater streams}, journal = {Journal of Applied Ecology}, volume = {53}, year = {2016}, pages = {1543{\textendash}1553}, abstract = {
  1. Fire and grazing are common in grasslands world-wide to maintain grass cover and cattle production. The effects of fire, cattle grazing and riparian fencing efficacy on prairie stream ecology are not well characterized at catchment scales.
  2. We examined alterations to stream water quality and biology from patch-burn grazing (PBG) in tallgrass prairie during a five-year, replicated, catchment scale experiment that used a Before-After/Control-Impact (BACI) design and was analysed by mixed-effects models. Treatments included two patch-burned control catchments (fire but no grazers) and PBG in two riparian-fenced and two unfenced catchments. We assessed the effectiveness of riparian fencing for mitigating potential water quality impacts by monitoring water quality and riparian usage by cattle via Global Positioning System.
  3. Riparian fences effectively excluded cattle; however, in unfenced pastures, cattle aggregated along streams 10\–20\% of the grazing season.
  4. After initiation of PBG, we detected large increases in some nutrients, Escherichia coli, algal biomass, primary productivity and community respiration in all catchments with PBG. Some water quality variables, such as E.\ coli concentrations, recovered quickly after cattle were removed from pasture, which indicated resiliency.
  5. Riparian fencing moderately reduced the impacts to stream variables, indicating either overland flow and/or subsurface flow allowed nutrients and bacteria to enter the streams.
  6. Synthesis and applications. Patch-burn grazing is a measurable disturbance that can alter the ecological condition of streams. Riparian fencing lessened the degree of impact, yet some water quality variables still exceeded regional reference conditions. Managers will need to assess the costs of riparian fencing compared to the moderate benefits that fencing provides to water quality.
}, keywords = {LTER-KNZ}, doi = {10.1111/1365-2664.12692}, url = {https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2664.12692}, author = {Larson, D.M. and W. K. Dodds and M.R. Whiles and .Thompson, T.R. and Fulgoni, J.N.} } @article {KNZ001730, title = {Few multiyear precipitation{\textendash}reduction experiments find a shift in the productivity{\textendash}precipitation relationship}, journal = {Global Change Biology}, volume = {22}, year = {2016}, pages = {2570-2581}, abstract = {

Well-defined productivity\–precipitation relationships of ecosystems are needed as benchmarks for the validation of land models used for future projections. The productivity\–precipitation relationship may be studied in two ways: the spatial approach relates differences in productivity to those in precipitation among sites along a precipitation gradient (the spatial fit, with a steeper slope); the temporal approach relates interannual productivity changes to variation in precipitation within sites (the temporal fits, with flatter slopes). Precipitation\–reduction experiments in natural ecosystems represent a complement to the fits, because they can reduce precipitation below the natural range and are thus well suited to study potential effects of climate drying. Here, we analyse the effects of dry treatments in eleven multiyear precipitation\–manipulation experiments, focusing on changes in the temporal fit. We expected that structural changes in the dry treatments would occur in some experiments, thereby reducing the intercept of the temporal fit and displacing the productivity\–precipitation relationship downward the spatial fit. The majority of experiments (72\%) showed that dry treatments did not alter the temporal fit. This implies that current temporal fits are to be preferred over the spatial fit to benchmark land-model projections of productivity under future climate within the precipitation ranges covered by the experiments. Moreover, in two experiments, the intercept of the temporal fit unexpectedly increased due to mechanisms that reduced either water loss or nutrient loss. The expected decrease of the intercept was observed in only one experiment, and only when distinguishing between the late and the early phases of the experiment. This implies that we currently do not know at which precipitation\–reduction level or at which experimental duration structural changes will start to alter ecosystem productivity. Our study highlights the need for experiments with multiple, including more extreme, dry treatments, to identify the precipitation boundaries within which the current temporal fits remain valid.

}, keywords = {LTER-KNZ}, doi = {10.1111/gcb.13269}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.13269}, author = {Estiarte, M. and Vicca, S. and Pe{\~n}uelas, J. and Michael Bahn and Beier, C. and Emmett, B.A. and Fay, P.A. and Hanson, P.J. and R. Hasibeder and Kigel, J. and Kr{\"o}el-Dulay, G. and Larsen, K.S. and Lellei-Kov{\'a}cs, E. and Limousin, J-M. and Ogaya, R. and Ourcival, J-M. and Reinsch, S. and Sala, O.E. and Schmidt, I.K. and Sternberg, M. and Tielb{\"o}rger, K. and Tietema, A. and Janssens, I.A.} } @article {KNZ001867, title = {Methods of approximation influence aquatic ecosystem metabolism estimates}, journal = {Limnology and Oceanography: Methods}, volume = {14}, year = {2016}, pages = {557 - 569}, abstract = {

Aquatic ecologists have recently employed dynamic models to estimate aquatic ecosystem metabolism. All approaches involve numerically solving a differential equation describing dissolved oxygen (DO) dynamics. Although the DO differential equation can be solved accurately with linear multistep or Runge\–Kutta methods, less accurate methods, such as the Euler method, have been applied. The methods also differ in how discrete temperature and light measurements are used to drive DO dynamics. Here, we used a representative stream DO data set to compare the metabolism estimates generated by multiple Euler based methods and an accurate numerical method. We also compared metabolism estimates using linear, piecewise constant and smoothing spline interpolation of light and temperature. Using observed DO to calculate DO saturation deficit in the Euler method results in a substantial difference in metabolism estimates compared to all other methods. If modeled DO is used to calculate DO saturation deficit, the Euler method introduces smaller error in metabolism estimates, which diminishes as logging interval decreases. Linear and smoothing spline interpolation result in similar metabolism estimates, but differ from estimates based on piecewise constant interpolation. We demonstrate how different computational methods imply distinct assumptions about process and observation error, and conclude that under the assumption of observation error, the best practice is to use the accurate numerical method of solving differential equation with a continuous interpolation of light and temperature. The Euler method will introduce minimal error if it is paired with frequently logged data and DO saturation deficit is computed using modeled DO.

}, keywords = {LTER-KNZ}, doi = {10.1002/lom3.10112}, url = {https://aslopubs.onlinelibrary.wiley.com/doi/full/10.1002/lom3.10112}, author = {Song, Chao and W. K. Dodds and Trentman, Matt T. and R{\"u}egg, Janine and Ballantyne, Ford} } @article {KNZ001798, title = {Quantifying global soil carbon losses in response to warming}, journal = {Nature}, volume = {540}, year = {2016}, pages = {104 - 108}, abstract = {

The majority of the Earth\’s terrestrial carbon is stored in the soil. If anthropogenic warming stimulates the loss of this carbon to the atmosphere, it could drive further planetary warming, Despite evidence that warming enhances carbon fluxes to and from the soil, the net global balance between these responses remains uncertain. Here we present a comprehensive analysis of warming-induced changes in soil carbon stocks by assembling data from 49 field experiments located across North America, Europe and Asia. We find that the effects of warming are contingent on the size of the initial soil carbon stock, with considerable losses occurring in high-latitude areas. By extrapolating this empirical relationship to the global scale, we provide estimates of soil carbon sensitivity to warming that may help to constrain Earth system model projections. Our empirical relationship suggests that global soil carbon stocks in the upper soil horizons will fall by 30\ \±\ 30 petagrams of carbon to 203\ \±\ 161 petagrams of carbon under one degree of warming, depending on the rate at which the effects of warming are realized. Under the conservative assumption that the response of soil carbon to warming occurs within a year, a business-as-usual climate scenario would drive the loss of 55\ \±\ 50 petagrams of carbon from the upper soil horizons by 2050. This value is around 12\–17 per cent of the expected anthropogenic emissions over this period. Despite the considerable uncertainty in our estimates, the direction of the global soil carbon response is consistent across all scenarios. This provides strong empirical support for the idea that rising temperatures will stimulate the net loss of soil carbon to the atmosphere, driving a positive land carbon\–climate feedback that could accelerate climate change.

}, keywords = {LTER-KNZ, Biogeochemistry, carbon cycle}, doi = {10.1038/nature20150}, url = {https://www.nature.com/articles/nature20150}, author = {Crowther, T. W. and Todd-Brown, K. E. O. and Rowe, C. W. and Wieder, W. R. and Carey, J. C. and Machmuller, M. B. and Snoek, B. L. and Fang, S. and Zhou, G. and Allison, S. D. and John M. Blair and Bridgham, S. D. and Burton, A. J. and Carrillo, Y. and Reich, P. B. and Clark, J. S. and Classen, A. T. and Dijkstra, F. A. and Elberling, B. and Emmett, B. A. and Estiarte, M. and Frey, S. D. and Guo, J. and Harte, J. and Jiang, L. and Johnson, B. R. and Kr{\"o}el-Dulay, G. and Larsen, K. S. and Laudon, H. and Lavallee, J. M. and Luo, Y. and Lupascu, M. and Ma, L. N. and Marhan, S. and Michelsen, A. and Mohan, J. and Niu, S. and Pendall, E. and {\~n}uelas, J. and Pfeifer-Meister, L. and Poll, C. and Reinsch, S. and Reynolds, L. L. and Schmidt, I. K. and Sistla, S. and Sokol, N. W. and Templer, P. H. and Treseder, K. K. and Welker, J. M. and Bradford, M. A.} } @article {KNZ001781, title = {Rangeland responses to predicted increases in drought extremity}, journal = {Rangelands }, volume = {38}, year = {2016}, pages = {191-196}, keywords = {LTER-KNZ, Drought, grassland, savanna, shrubland, state and transition, woodland}, url = {http://dx.doi.org/10.1016/j.rala.2016.06.009}, author = {Breshears, D.D. and Alan K. Knapp and Law, D.J. and M.D. Smith and Twidwell, D. and Wonkka, C.L.} } @article {KNZ001748, title = {Shared drivers but divergent ecological responses: Insights from long-term experiments in mesic savanna grasslands}, journal = {BioScience}, volume = {66}, year = {2016}, pages = {666 - 682}, type = {Journal Articles}, abstract = {

Fire and grazing, key determinants of structure and function of savanna grasslands worldwide, have been extensively altered by humans. We used existing long-term manipulations of fire and grazing in North American and South African mesic savanna grasslands, as well as new experiments, to determine whether the impacts of fire and grazing by large herbivores differed between these systems. We found that despite a body of literature suggesting that these savanna grasslands respond uniquely to fire and grazing, their ecosystem responses (aboveground productivity) were generally similar. In contrast, plant-community responses to fire and herbivores diverged strongly between systems. The differences in plant-community responses, as well as convergence in ecosystem function, were underpinned by a common mechanism: the response of grass dominance to changing fire and grazing regimes. As a result, divergent responses of plant communities to altered fire and grazing regimes did not preclude convergence in ecosystem function.

}, keywords = {LTER-KNZ, Aboveground net primary productivity, fire, grassland, Grazing, plant community}, doi = {10.1093/biosci/biw077}, url = {https://academic.oup.com/bioscience/article/66/8/666/2464141}, author = {M.D. Smith and Alan K. Knapp and Scott. L. Collins and Burkepile, D.E. and Kirkman, K.P. and Koerner, S.E. and Thompson, D.I. and John M. Blair and Burns, C.E. and Eby, S. and Forrestel, E.J. and Fynn, R.W.S. and Govender, N. and Hagenah, N. and Hoover, D.L. and K.R. Wilcox} } @article {KNZ001873, title = {Shrews and their parasites: small species indicate big changes}, journal = {NOAA Arctic Report Card}, year = {2016}, abstract = {

As Arctic climate warms, how will terrestrial ecosystems and interconnected communities respond in the coming decades? Small mammals, such as shrews, and their parasites can serve as key indicators for anticipating the consequences of accelerating environmental perturbation and changing interactions among species. Some Arctic shrews have recently acquired new parasites indicating poleward shifts of sub-Arctic faunas, and demonstrating increases in both Arctic biodiversity and overall complexity within these novel species networks. Spatially broad and temporally deep specimen collections of small mammals and parasites are revealing the extent and nature of community reorganization as northern faunas adjust to accelerating climate change.

}, keywords = {LTER-KNZ}, url = {http://www.arctic.noaa.gov/Report-Card}, author = {Hope, A.G. and Greiman, S.E. and Tkach, V.V. and Hoberg, E.P. and Cook, J.A.} } @article {KNZ001773, title = {Factors affecting female space use in ten populations of prairie chickens}, journal = {Ecosphere}, volume = {6}, year = {2015}, pages = {art166}, abstract = {

Conservation of wildlife depends on an understanding of the interactions between animal movements and key landscape factors. Habitat requirements of wide-ranging species often vary spatially, but quantitative assessment of variation among replicated studies at multiple sites is rare. We investigated patterns of space use for 10 populations of two closely related species of prairie grouse: Greater Prairie-Chickens (Tympanuchus cupido) and Lesser Prairie-Chickens (T. pallidicinctus). Prairie chickens require large, intact tracts of native grasslands, and are umbrella species for conservation of prairie ecosystems in North America. We used resource utilization functions to investigate space use by female prairie chickens during the 6-month breeding season from March through August in relation to lek sites, habitat conditions, and anthropogenic development. Our analysis included data from 382 radio-marked individuals across a major portion of the extant range. Our project is a unique opportunity to study comparative space use of prairie chickens, and we employed standardized methods that facilitated direct comparisons across an ecological gradient of study sites. Median home range size of females varied ~10-fold across 10 sites (3.6\–36.7 km2), and home ranges tended to be larger at sites with higher annual precipitation. Proximity to lek sites was a strong and consistent predictor of space use for female prairie chickens at all 10 sites. The relative importance of other predictors of space use varied among sites, indicating that generalized habitat management guidelines may not be appropriate for these two species. Prairie chickens actively selected for prairie habitats, even at sites where ~90\% of the land cover within the study area was prairie. A majority of the females monitored in our study (\>95\%) had activity centers within 5 km of leks, suggesting that conservation efforts can be effectively concentrated near active lek sites. Our data on female space use suggest that lek surveys of male prairie chickens can indirectly assess habitat suitability for females during the breeding season. Lek monitoring and surveys for new leks provide information on population trends, but can also guide management actions aimed at improving nesting and brood-rearing habitats.

}, keywords = {LTER-KNZ}, doi = {10.1890/ES14-00536.1}, url = {https://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/ES14-00536.1}, author = {Winder, V.L. and Carrlson, K.M. and Gregory, A.J. and Hagen, C.A. and David A. Haukos and Kesler, D.C. and Larsson, L.C. and Matthews, T.W. and McNew, L.B. and Patten, M.A. and Pitman, J.C. and Powell, L.A. and Smith, J.A. and Thompson, T. and Wolfe, D.H. and Sandercock, B.K.} } @article {KNZ001777, title = {Quantifying ambient nitrogen uptake and functional relationships of uptake versus concentration in streams: a comparison of stable isotope, pulse, and plateau approaches}, journal = {Biogeochemistry}, volume = {125}, year = {2015}, pages = {65 - 79}, abstract = {

Nutrient releases and spiraling metrics are frequently used to quantify the downstream transport of nutrients and to better understand the effects of anthropogenic inputs to downstream waters. Ambient uptake rates in streams can be measured through stable isotope enrichments, while pulse and plateau additions can estimate such rates via extrapolation and modeling techniques, respectively. Data from these releases can be used to estimate ambient uptake rates from nutrient additions and possibly determine the functional relationships between nutrient concentrations and uptake rates. Here, we compared estimated ambient rates calculated from established pulse and plateau approaches, results obtained from new modeling approaches, and rates at ambient concentrations from stable isotope enrichments. Comparative releases of NH4Cl and 15NH4Cl were conducted in four experimental reaches across the grassland Kings Creek and urban Campus Creek, KS. Nutrient uptake was predominantly linear with increasing ammonium. Estimated ambient uptake rates varied among sites, release methods, and data analysis approaches. However, plateau ambient rates from new modeling approaches matched closely with measured ambient rates from isotope enrichments at three sites, suggesting that modeled plateau data may be best for a first look at determining nutrient uptake rates at an individual site. Limitations and benefits of each approach vary; however, baseflow discharge may be a key driver when choosing a method. If possible, multiple methods should be attempted at each location and under each novel set of conditions to determine the best approach prior to designing and implementing a more extensive series of measurements.

}, keywords = {LTER-KNZ, Ammonium uptake, nutrient spiraling, TASCC, uptake length}, doi = {10.1007/s10533-015-0112-5}, url = {https://link.springer.com/article/10.1007\%2Fs10533-015-0112-5}, author = {Trentman, M.T. and W. K. Dodds and Fencl, J.S. and Gerber, K. and Guarneri, J. and Hitchman, S.M. and Peterson, Z. and R{\"u}egg, J.} } @article {KNZ001675, title = {Thermal performance of larval longfin dace (Agosia chrysogaster), with implications for climate change}, journal = {Environmental Biology of Fishes}, volume = {98}, year = {2015}, pages = {395 -404}, abstract = {

Temperature is an important factor affecting the distribution of freshwater fishes. The longfin dace (Agosia chrysogaster) is endemic to the Gila River basin of the southwestern USA and northern Mexico and occupies a range of thermal environments from cool mountain tributaries to warm desert rivers but information about its thermal biology is limited, particularly for larvae. We quantified the effect of rearing temperature on survival, growth capacity, and critical thermal maximum (CTM) of larval longfin dace. Broodstocks of longfin dace were collected from two sites in the upper Gila River in New Mexico from which larvae were hatched and reared for 22 days in indoor aquaria at constant temperatures ranging from 18.0 to 31.0 \°C. Growth capacity peaked at 27.0 \°C and was 21 \% greater for larvae hatched from the upstream compared to the downstream broodstock, indicating intraspecific variability in growth capacity. CTM increased with rearing temperature and ranged from 33.9 to 39.9 \°C, indicating that thermal acclimation influences maximum thermal tolerance. CTM and acclimation response ratio of larvae are lower than those of adult longfin dace measured in a previous study, suggesting that larvae are more sensitive and less responsive to thermal stress than adults. Water temperatures in 2012 from six sites in the upper Gila River basin did not exceed 27.0 \°C and larval growth capacities in May of 2012 ranged from 5 to 28 \% of the maximum growth capacity. We assert that rising temperatures may increase larval growth rates, although this will depend on resource limitation and shifts in community interactions.

}, keywords = {LTER-KNZ, Critical thermal maximum, GilaRiver, Growth capacity, Larval fish, Thermal acclimation}, doi = {10.1007/s10641-014-0270-7}, url = {https://link.springer.com/article/10.1007\%2Fs10641-014-0270-7}, author = {Troia, M.J. and Whitney, J.E. and K. B. Gido} } @inbook {KNZ002019, title = {Agriculture, Forestry and Other Land Use (AFOLU)}, booktitle = {Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change }, year = {2014}, pages = {811-922}, publisher = {Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.}, organization = {Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.}, chapter = {11}, keywords = {LTER-KNZ}, url = {https://www.ipcc.ch/report/ar5/wg3/agriculture-forestry-and-other-land-use-afolu/}, author = {Smith, P. and Bustamante, M. and Ahammad, H. and Clark, H. and Dong, H. and Elsiddig, E. A. and Haberl, H. and Harper, R. and J. House and M. Jafari and O. Masera and C. Mbow and N.H. Ravindranath and C. W. Rice and C. Robledo Abad and A. Romanovskaya and F. Sperling and F. Tubiello} } @article {KNZ001674, title = {Alternative spawning strategy and temperature for larval emergence of longfin dace (Agosia chrysogaster) in stream mesocosms}, journal = {The Southwestern Naturalist}, volume = {59}, year = {2014}, pages = {277-280}, abstract = {

To determine if the strategy of spawning in saucer-like depressions is obligate or facultative for longfin dace (Agosia chrysogaster), we collected adults from four sites in the upper Gila River (southwestern New Mexico), stocked them in separate outdoor stream-mesocosms lined with cobble substrate, and made daily observations for the presence of saucer-nests and hatched larvae. Larvae were observed from three of the four mesocosms and emerged at temperatures ranging from 19.2\–24.0\°C. The absence of saucer-nests in all mesocosms throughout the study indicates that longfin dace can spawn over cobble substrate and have larvae hatch successfully, suggesting that longfin dace can use an alternate spawning strategy when sand substrate is not available for construction of saucer-nests.

}, keywords = {LTER-KNZ}, doi = {10.1894/N03-MP-09.1}, url = {http://www.bioone.org/doi/10.1894/N03-MP-09.1}, author = {Troia, M.J. and Whitney, J.E. and K. B. Gido} } @article {KNZ001589, title = {Biotic mechanisms of community stability shift along a precipitation gradient}, journal = {Ecology}, volume = {95}, year = {2014}, pages = {1693 -1700}, abstract = {

Understanding how biotic mechanisms confer stability in variable environments is a fundamental quest in ecology, and one that is becoming increasingly urgent with global change. Several mechanisms, notably a portfolio effect associated with species richness, compensatory dynamics generated by negative species covariance and selection for stable dominant species populations can increase the stability of the overall community. While the importance of these mechanisms is debated, few studies have contrasted their importance in an environmental context. We analyzed nine long-term data sets of grassland species composition to investigate how two key environmental factors, precipitation amount and variability, may directly influence community stability and how they may indirectly influence stability via biotic mechanisms. We found that the importance of stability mechanisms varied along the environmental gradient: strong negative species covariance occurred in sites characterized by high precipitation variability, whereas portfolio effects increased in sites with high mean annual precipitation. Instead of questioning whether compensatory dynamics are important in nature, our findings suggest that debate should widen to include several stability mechanisms and how these mechanisms vary in importance across environmental gradients.

}, keywords = {LTER-KNZ}, doi = {10.1890/13-0895.1}, url = {https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/13-0895.1}, author = {Hallett, L.M. and Hsu, J.S. and Cleland, E.E. and Scott. L. Collins and Dickson, T.L. and Farrer, E.C. and Gherardi, L.A. and Gross, K.L. and Hobbs, R.J. and Turnbull, L. and K.N. Suding} } @article {KNZ001633, title = {Differential effects of extreme drought on production and respiration: Synthesis and modeling analysis}, journal = {Biogeosciences}, volume = {11}, year = {2014}, pages = {621 -633}, abstract = {

Extremes in climate may severely impact ecosystem structure and function, with both the magnitude and rate of response differing among ecosystem types and processes. We conducted a modeling analysis of the effects of extreme drought on two key ecosystem processes, production and respiration, and, to provide a broader context, we complemented this with a synthesis of published results that cover a wide variety of ecosystems. The synthesis indicated that across a broad range of biomes, gross primary production (GPP) was generally more sensitive to extreme drought (defined as proportional reduction relative to average rainfall periods) than was ecosystem respiration (ER). Furthermore, this differential sensitivity between production and respiration increased as drought severity increased; it occurred only in grassland ecosystems, and not in evergreen needle-leaf and broad-leaf forests or woody savannahs. The modeling analysis was designed to enable a better understanding of the mechanisms underlying this pattern, and focused on four grassland sites arrayed across the Great Plains, USA. Model results consistently showed that net primary productivity (NPP) was reduced more than heterotrophic respiration (Rh) by extreme drought (i.e., 67\% reduction in annual ambient rainfall) at all four study sites. The sensitivity of NPP to drought was directly attributable to rainfall amount, whereas the sensitivity of Rh to drought was driven by soil drying, reduced carbon (C) input and a drought-induced reduction in soil C content \– a much slower process. However, differences in reductions in NPP and Rh diminished as extreme drought continued, due to a gradual decline in the soil C pool leading to further reductions in Rh. We also varied the way in which drought was imposed in the modeling analysis; it was either imposed by simulating reductions in rainfall event size (ESR) or by reducing rainfall event number (REN). Modeled NPP and Rh decreased more by ESR than REN at the two relatively mesic sites but less so at the two xeric sites. Our findings suggest that responses of production and respiration differ in magnitude, occur on different timescales, and are affected by different mechanisms under extreme, prolonged drought.

}, keywords = {LTER-KNZ}, doi = {10.5194/bg-11-621-2014}, url = {https://www.biogeosciences.net/11/621/2014/}, author = {Shi, Z. and Thomey, M.L. and Mowll, M. and Litvak, M.E. and N. Brunsell and Scott. L. Collins and Pockman, W.T. and M.D. Smith and Alan K. Knapp and Luo, Y.} } @article {KNZ001643, title = {Ecological consequences of shifting the timing of burning tallgrass prairie}, journal = {PLOS One}, volume = {9: e103423}, year = {2014}, abstract = {

In the Kansas Flint Hills, grassland burning is conducted during a relatively narrow window because management recommendations for the past 40 years have been to burn only in late spring. Widespread prescribed burning within this restricted time frame frequently creates smoke management issues downwind. A potential remedy for the concentrated smoke production in late spring is to expand burning to times earlier in the year. Yet, previous research suggested that burning in winter or early spring reduces plant productivity and cattle weight gain while increasing the proportion of undesirable plant species. In order to better understand the ecological consequences of burning at different times of the year, plant production and species abundance were measured for 20 years on ungrazed watersheds burned annually in autumn, winter, or spring. We found that there were no significant differences in total grass production among the burns on either upland or lowland topographic positions, although spring burned watersheds had higher grass culm production and lower forb biomass than autumn and winter burned watersheds. Burning in autumn or winter broadened the window of grass productivity response to precipitation, which reduces susceptibility to mid-season drought. Burning in autumn or winter also increased the phenological range of species by promoting cool-season graminoids without a concomitant decrease in warm-season grasses, potentially widening the seasonal window of high-quality forage. Incorporating autumn and winter burns into the overall portfolio of tallgrass prairie management should increase the flexibility in managing grasslands, promote biodiversity, and minimize air quality issues caused by en masse late-spring burning with little negative consequences for cattle production.

}, keywords = {LTER-KNZ}, doi = {10.1371/journal.pone.0103423}, url = {https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0103423}, author = {Towne, E.G. and Craine, J.M.} } @article {KNZ001637, title = {FOAM: Functional Ontology Assignments for Metagenomes: a Hidden Markov Model (HMM) database with environmental focus}, journal = {Nucleic Acids Research}, volume = {42: e145}, year = {2014}, abstract = {

A new functional gene database, FOAM (Functional Ontology Assignments for Metagenomes), was developed to screen environmental metagenomic sequence datasets. FOAM provides a new functional ontology dedicated to classify gene functions relevant to environmental microorganisms based on Hidden Markov Models (HMMs). Sets of aligned protein sequences (i.e. \‘profiles\’) were tailored to a large group of target KEGG Orthologs (KOs) from which HMMs were trained. The alignments were checked and curated to make them specific to the targeted KO. Within this process, sequence profiles were enriched with the most abundant sequences available to maximize the yield of accurate classifier models. An associated functional ontology was built to describe the functional groups and hierarchy. FOAM allows the user to select the target search space before HMM-based comparison steps and to easily organize the results into different functional categories and subcategories. FOAM is publicly available at http://portal.nersc.gov/project/m1317/FOAM/.

}, keywords = {LTER-KNZ}, doi = {10.1093/nar/gku702}, url = {https://academic.oup.com/nar/article/42/19/e145/2902479}, author = {Prestat, E. and David, M. and Hultman, J. and Tas, N. and Lamendella, R. and Dvornik, J. and Mackelprang, R. and Myrold, D.D. and A. Jumpponen and Tringe, S. and Holman, E. and Mavromatis, K. and Jansson, J.K.} } @article {KNZ002020, title = {Knowledge and tools to enhance resilience of beef grazing systems for sustainable animal protein production}, journal = {Annals of the New York Academy of Sciences}, volume = {1328}, year = {2014}, pages = {10 - 17}, keywords = {LTER-KNZ}, doi = {10.1111/nyas.12572}, url = {https://www.ncbi.nlm.nih.gov/pubmed/25376887}, author = {Steiner, Jean L. and Engle, David M. and Xiao, Xiangming and Saleh, Ali and Tomlinson, Peter and C. W. Rice and Cole, N. Andy and Coleman, Samuel W. and Osei, Edward and Basara, Jeffrey and Middendorf, Gerad and Gowda, Prasanna and Todd, Richard and Moffet, Corey and Anandhi, Aavudai and Starks, Patrick J. and Ocshner, Tyson and Reuter, Ryan and Devlin, Daniel} } @article {KNZ001588, title = {Loss of a large grazer impacts savanna grassland plant communities similarly in North America and South Africa}, journal = {Oecologia}, volume = {175}, year = {2014}, pages = {293 -303}, abstract = {

Large herbivore grazing is a widespread disturbance in mesic savanna grasslands which increases herbaceous plant community richness and diversity. However, humans are modifying the impacts of grazing on these ecosystems by removing grazers. A more general understanding of how grazer loss will impact these ecosystems is hampered by differences in the diversity of large herbivore assemblages among savanna grasslands, which can affect the way that grazing influences plant communities. To avoid this we used two unique enclosures each containing a single, functionally similar large herbivore species. Specifically, we studied a bison (Bos bison) enclosure at Konza Prairie Biological Station, USA and an African buffalo (Syncerus caffer) enclosure in Kruger National Park, South Africa. Within these enclosures we erected exclosures in annually burned and unburned sites to determine how grazer loss would impact herbaceous plant communities, while controlling for potential fire-grazing interactions. At both sites, removal of the only grazer decreased grass and forb richness, evenness and diversity, over time. However, in Kruger these changes only occurred with burning. At both sites, changes in plant communities were driven by increased dominance with herbivore exclusion. At Konza, this was caused by increased abundance of one grass species, Andropogon gerardii, while at Kruger, three grasses, Themeda triandra, Panicum coloratum, and Digitaria eriantha increased in abundance.

}, keywords = {LTER-KNZ, disturbance, fire, Grazing, Plant community richness, Species diversity}, doi = {10.1007/s00442-014-2895-9}, url = {https://link.springer.com/article/10.1007\%2Fs00442-014-2895-9}, author = {Eby, S. and Burkepile, D.E. and Fynn, R.W.S. and Burns, C.E. and Govender, N. and Hagenah, N. and Koerner, S.E. and Matchett, K.J. and Thompson, D.I. and K.R. Wilcox and Scott. L. Collins and Kirkman, K.P. and Alan K. Knapp and M.D. Smith} } @phdthesis {KNZ001654, title = {A mechanistic framework for understanding prairie stream fish distributions}, volume = {PhD. Dissertation}, year = {2014}, school = {Kansas State University}, type = {Ph.D. Thesis}, address = {Manhattan, KS}, abstract = {

A fundamental goal of ecology is to understand environmental associations of species. These associations can provide a basis for predicting spatial distributions in contemporary habitats as well as how those distributions might change in response to anthropogenic environmental change. Developing species distribution models is limited by an incomplete understanding of functional traits, spatial scaling, and the mechanisms and generalities of correlations among abundance and environmental gradients. I address these four issues using observational and experimental approaches. First, I tested opposing mechanisms of community assembly by measuring the dispersion (i.e., diversity) of three types of functional strategies at three spatial scales and along environmental gradients. I found that communities are assembled via abiotic environmental filtering, but the strength of this filtering depends on the spatial scale of investigation, longitudinal network position, and type of functional strategy. Second, I quantified community-environment relationships across thirteen sub-basins, nested within the three major basins within Kansas to evaluate the consistency (i.e., generality) in predictive capability of environmental variables among sub-basins and across spatial extents. I found that longitudinal network position is consistently the strongest predictor of community composition among sub-basins, but in-stream and catchment predictors become stronger correlates of community composition with increasing spatial extent. Third, I used environmental niche models to quantify distributions of four pairs of congeneric cyprinids and found that species within each pair exhibited contrasting stream-size preferences. I then used field experiments to test for differences in individual-level performance between one pair of species (Pimephales notatus and P. vigilax) along a gradient of stream size. I found that adult spawn success and juvenile growth and condition increased with stream size for both species, indicating that these congeners respond similarly to abiotic gradients associated with the river continuum. I concluded that complementary distributions are a consequence of biotic interactions, differential environmental filtering evident in an unmeasured performance metric, or differential environmental filtering by an environmental factor operating at longer timescales. These studies demonstrate the context dependencies of characterizing habitat associations of stream fishes, but also reveal the general importance of stream size and associated environmental gradients in structuring stream fish communities.

}, keywords = {LTER-KNZ, Community ecology, Environmental niche modeling, Fish ecology}, url = {http://hdl.handle.net/2097/17285}, author = {Troia, M.J.} } @article {KNZ001605, title = {Naphthalene addition to soil surfaces: A feasible method to reduce soil micro-arthropods with negligible direct effects on soil C dynamics}, journal = {Applied Soil Ecology}, volume = {74}, year = {2014}, pages = {21 -29}, abstract = {

Soil fauna are a key component of soil biodiversity and a driver of soil functioning. While the importance of soil fauna is well recognized, quantitative estimates of the role of soil fauna on soil biogeochemical processes, such as plant litter decomposition, are limited by methodological constraints. The addition of naphthalene, a polycyclic aromatic hydrocarbon (C10H8), to suppress soil fauna has been used for decades in decomposition experiments, but its efficacy remains questioned. In fact, we lack a rigorous field assessment of the efficacy of naphthalene additions for soil fauna suppression and potential non-target effects on the soil microbial community and carbon cycling. We added naphthalene at a high rate (477 g m\−2) monthly for 23 months on the bare soil surface of a tallgrass prairie. We determined the effect of such additions on the abundance of nematodes and micro-arthropods along the soil profile to a depth of 20 cm at 11, 16 and 23 months after initiating naphthalene application. We used the variation in the natural 13C abundance of the naphthalene (δ13C \– 25.5\‰) as compared to the native soil (δ13C \∼ \−17\‰) to quantify naphthalene contribution to soil CO2 efflux and microbial biomarkers (PLFA). Naphthalene addition significantly reduced the abundance of oribatid mites (\−45\%), predatory mites (\−52\%) and springtails (\−49\%), but did not affect nematode abundance. The 13C abundance of a few Gram-negative (cy17:0, 18:1ω7c, 16:1ω7c), Gram-positive (a15:0, i15:0) and Actinobacteria (10Me-16:0, 10Me-18:0) PLFA markers decreased significantly in naphthalene treated plots, indicating bacterial utilization of naphthalene-derived C. Mixing models showed this contribution to be highly variable, with the highest naphthalene-C incorporation for Gram negative bacteria. Naphthalene-C was not incorporated in fungal PLFAs. This microbial utilization did not affect overall microbial abundance, community structure or activity, estimated as soil respiration. This experiment proves that naphthalene addition is a feasible method to reduce soil micro-arthropods in the field, with negligible direct effects on soil nematodes, microbial abundance and C dynamics.

}, keywords = {LTER-KNZ, Fauna manipulation methods, Mites, Nematodes, PLFA, Springtails, Stable C isotopes}, doi = {10.1016/j.apsoil.2013.09.008}, url = {https://www.sciencedirect.com/science/article/pii/S0929139313002400?via\%3Dihub}, author = {Cotrufo, M.F. and Soong, J. and Vandegehuchte, M.L. and Ngryen, T. and Denef, K. and Shaw, E.A. and Sylvain, Z.A. and Tomasel, C.M.D. and Nielsen, U.N. and Wall, D.H.} } @article {KNZ001590, title = {Plant community response to loss of large herbivores differs between North American and South African savanna grasslands}, journal = {Ecology}, volume = {95}, year = {2014}, pages = {808 -816}, abstract = {

Herbivory and fire shape plant community structure in grass-dominated ecosystems, but these disturbance regimes are being altered around the world. To assess the consequences of such alterations, we excluded large herbivores for seven years from mesic savanna grasslands sites burned at different frequencies in North America (Konza Prairie Biological Station, Kansas, USA) and South Africa (Kruger National Park). We hypothesized that the removal of a single grass-feeding herbivore from Konza would decrease plant community richness and shift community composition due to increased dominance by grasses. Similarly, we expected grass dominance to increase at Kruger when removing large herbivores, but because large herbivores are more diverse, targeting both grasses and forbs, at this study site, the changes due to herbivore removal would be muted. After seven years of large-herbivore exclusion, richness strongly decreased and community composition changed at Konza, whereas little change was evident at Kruger. We found that this divergence in response was largely due to differences in the traits and numbers of dominant grasses between the study sites rather than the predicted differences in herbivore assemblages. Thus, the diversity of large herbivores lost may be less important in determining plant community dynamics than the functional traits of the grasses that dominate mesic, disturbance-maintained savanna grasslands.

}, keywords = {LTER-KNZ}, doi = {10.1890/13-1828.1}, url = {https://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/13-1828.1}, author = {Koerner, S.E. and Burkepile, D.E. and Fynn, R.W.S. and Burns, C.E. and Eby, S. and Govender, N. and Hagenah, N. and Matchett, K.J. and Thompson, D.I. and K.R. Wilcox and Scott. L. Collins and Kirkman, K.P. and Alan K. Knapp and M.D. Smith} } @article {KNZ001587, title = {Responses to fire differ between South African and North American grassland communities}, journal = {Journal of Vegetation Science}, volume = {25}, year = {2014}, pages = {793 -804}, abstract = {

Question Does fire frequency affect mesic grassland plant community structure and composition similarly in North America and South Africa? Location Konza Prairie Biological Station (KNZ), Kansas, USA, and Ukulinga Research Farm (URF), KwaZulu-Natal, South Africa. Methods Plant community structure and composition were compared among annually burned, unburned and intermediate treatments within two long-term fire frequency manipulation experiments in native grasslands in North America and South Africa using comparable methodology over a 5-yr period. Because fire may reduce soil nitrogen (N) availability and thus affect plant community structure, N additions were superimposed on the fire treatments as a means of assessing direct vs indirect mechanisms driving responses to fire. Results The total number of species was higher at URF (183) than at KNZ (57). Overall divergence in plant community response to fire frequency occurred despite similar responses to nutrient additions. At KNZ, more frequent fire resulted in dominance by a few, tall, deep-rooted rhizomatous grasses (e.g. Andropogon gerardii). On unburned sites, shorter, more shade-tolerant species such as Poa pratensis increased in abundance, although A. gerardii remained dominant. Species richness increased with decreasing fire frequency at KNZ. At URF, frequent fire resulted in short, diverse grassland weakly dominated by a range of grass species, including Themeda triandra, Tristachya leucothrix and Hyparrhenia hirta. Decreasing fire frequency reduced species richness and resulted in dominance by a few, relatively tall caespitose grasses such as Aristida junciformis. There was a complete turnover of dominant species between annually burned and unburned treatments at URF, while at KNZ A. gerardii and Sorghastrum nutans occurred across the range of treatments. N addition reduced species richness in both sites. Conclusions Different responses to fire frequency between KNZ and URF are likely linked to the dominant species and their characteristic traits, including height and method of clonal reproduction, with the rhizomatous growth form of A. gerardii dominating the North American grassland. South Africa does not have an equivalent grass species; instead, a range of tufted, non-rhizomatous species dominate across the fire frequency treatments at URF. Reductions in soil N due to frequent fire did not appear to be a common mechanism driving responses in community composition in these two grasslands.

}, keywords = {LTER-KNZ, Community ecology, Divergence, Fire frequency, Konza Prairie Biological Station, Mesic grassland, nitrogen, Nutrient addition, Richness, tallgrass prairie, Ukulinga Research Farm}, doi = {10.1111/jvs.12130}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/jvs.12130}, author = {Kirkman, K. and Scott. L. Collins and M.D. Smith and Alan K. Knapp and Burkepile, D.E. and Burns, C.E. and Fynn, R.W.S. and Hagenah, N. and Koerner, S.E. and Matchett, K.J. and Thompson, D.I. and K.R. Wilcox and Wragg, P.D.} } @article {KNZ001644, title = {Towards a mechanistic understanding of fish species niche divergence along a river continuum}, journal = {Ecosphere}, volume = {5:art41}, year = {2014}, abstract = {

Environmental niche modeling is a valuable tool but it often fails to identify causal links between environmental gradients and individual- or population-level performance that drive species\&$\#$39; distributions. Correlation between the abundances of stream fish species and longitudinal position in stream networks is well documented and is hypothesized to occur through differential environmental filtering of trophic traits. Still, trophically similar congeners often exhibit complementary distributions along stream size gradients, suggesting that other mechanisms are important. We present niche models to test the hypothesis that four congeneric pairs (Teleostei: Cyprinidae) exhibit complementary distributions along a gradient of stream size in the central Great Plains of Kansas, USA. Stream size was the strongest predictor of abundance compared to five other environmental variables tested and three of the four species pairs exhibited complementary distributions along a stream size gradient. We carried out field experiments to quantify potentially causal environmental gradients (food resources, temperature, and turbidity) and four measures of individual performance (adult spawning success and juvenile survival, condition, and growth) along a stream size gradient for one congeneric pair: Pimephales notatus, a tributary species and P. vigilax, a river mainstem species. These experiments revealed an increase in temperature and food resources with stream size, along with a corresponding increase in adult spawning success, juvenile condition, and juvenile growth for both species. We conclude that these congeners respond similarly to abiotic gradients associated with the river continuum and that complementary distributions are a consequence of biotic interactions, differential environmental filtering evident in an unmeasured performance metric, or differential environmental filtering by a direct environmental gradient operating at longer timescales.

}, keywords = {LTER-KNZ}, doi = {10.1890/ES13-00399.1}, url = {https://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/ES13-00399.1}, author = {Troia, M.J. and K. B. Gido} } @article {KNZ001626, title = {You are not always what we think you eat: selective assimilation across multiple whole-stream isotopic tracer studies}, journal = {Ecology}, volume = {95}, year = {2014}, pages = {2757 -2767}, abstract = {

Analyses of 21 15N stable isotope tracer experiments, designed to examine food web dynamics in streams around the world, indicated that the isotopic composition of food resources assimilated by primary consumers (mostly invertebrates) poorly reflected the presumed food sources. Modeling indicated that consumers assimilated only 33\–50\% of the N available in sampled food sources such as decomposing leaves, epilithon, and fine particulate detritus over feeding periods of weeks or more. Thus, common methods of sampling food sources consumed by animals in streams do not sufficiently reflect the pool of N they assimilate. Isotope tracer studies, combined with modeling and food separation techniques, can improve estimation of N pools in food sources that are assimilated by consumers. Food web studies that use putative food samples composed of actively cycling (more readily assimilable) and refractory (less assimilable) N fractions may draw erroneous conclusions about diets, N turnover, and trophic linkages of consumers. By extension, food web studies using stoichiometric or natural abundance approaches that rely on an accurate description of food-source composition could result in errors when an actively cycling pool that is only a fraction of the N pool in sampled food resources is not accounted for.

}, keywords = {LTER-KNZ}, doi = {10.1890/13-2276.1}, url = {https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/13-2276.1}, author = {W. K. Dodds and Scott. L. Collins and Hamilton, S.K. and Tank, J.L. and Johnson, S. and Webster, J.R. and Simon, K.S. and M.R. Whiles and Rantala, H.M. and W.H. McDowell and Peterson, S.D. and Riis, T. and Crenshaw, C.L. and Thomas, S.A. and Kristensen, P.B. and Cheever, B.M. and Flecker, A.S. and Griffiths, N.A. and Crowl, T. and Rosi-Marshall, E.J. and El-Sabaawi, R. and Marti, E.} } @article {KNZ001538, title = {Coordinated distributed experiments: an emerging tool for testing global hypotheses in ecology and environmental science}, journal = {Frontiers in Ecology and the Environment}, volume = {11}, year = {2013}, pages = {147 -155}, abstract = {

There is a growing realization among scientists and policy makers that an increased understanding of today\&$\#$39;s environmental issues requires international collaboration and data synthesis. Meta-analyses have served this role in ecology for more than a decade, but the different experimental methodologies researchers use can limit the strength of the meta-analytic approach. Considering the global nature of many environmental issues, a new collaborative approach, which we call coordinated distributed experiments (CDEs), is needed that will control for both spatial and temporal scale, and that encompasses large geographic ranges. Ecological CDEs, involving standardized, controlled protocols, have the potential to advance our understanding of general principles in ecology and environmental science.

}, keywords = {LTER-KNZ}, doi = {10.1890/110279}, url = {https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/110279}, author = {Fraser, L.H. and Henry, H.A. and Carlyle, C.N. and White, S.R. and Beierkuhnlein, C. and Cahill, J.F. and Casper, B.B. and Cleland, E.E. and Scott. L. Collins and Dukes, J.S. and Alan K. Knapp and Lind, E. and Long, R. and Luo, Y. and P.B. Reich and M.D. Smith and Sternberg, M. and Turkington, R.} } @article {KNZ001740, title = {EO-1 Hyperion reflectance time series at calibration and validation sites: stability and sensitivity to seasonal dynamics}, journal = {IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing}, volume = {6}, year = {2013}, month = {Jan-04-2013}, pages = {276 - 290}, abstract = {

This study evaluated Earth Observing 1 (EO-1) Hyperion reflectance time series at established calibration sites to assess the instrument stability and suitability for monitoring vegetation functional parameters. Our analysis using three pseudo-invariant calibration sites in North America indicated that the reflectance time series are devoid of apparent spectral trends and their stability consistently is within 2.5-5 percent throughout most of the spectral range spanning the 12+ year data record. Using three vegetated sites instrumented with eddy covariance towers, the Hyperion reflectance time series were evaluated for their ability to determine important variables of ecosystem function. A number of narrowband and derivative vegetation indices (VI) closely described the seasonal profiles in vegetation function and ecosystem carbon exchange (e.g., net and gross ecosystem productivity) in three very different ecosystems, including a hardwood forest and tallgrass prairie in North America, and a Miombo woodland in Africa. Our results demonstrate the potential for scaling the carbon flux tower measurements to local and regional landscape levels. The VIs with stronger relationships to the CO2 parameters were derived using continuous reflectance spectra and included wavelengths associated with chlorophyll content and/or chlorophyll fluorescence. Since these indices cannot be calculated from broadband multispectral instrument data, the opportunity to exploit these spectrometer-based VIs in the future will depend on the launch of satellites such as EnMAP and HyspIRI. This study highlights the practical utility of space-borne spectrometers for characterization of the spectral stability and uniformity of the calibration sites in support of sensor cross-comparisons, and demonstrates the potential of narrowband VIs to track and spatially extend ecosystem functional status as well as carbon processes measured at flux towers.

}, keywords = {LTER-KNZ, calibration, geophysical techniques, remote sensing, vegetation}, issn = {1939-1404}, doi = {10.1109/JSTARS.2013.2246139}, url = {https://ieeexplore.ieee.org/document/6507569}, author = {Campbell, P.P.K. and Middleton, E.M. and Thome, K.J. and Kokaly, R.F. and Huemmrich, K.F. and Lagomasino, D. and Novick, K.A. and N. Brunsell} } @proceedings {KNZ001604, title = {Fungal community responses to discrete precipitation pulses under altered rainfall intervals}, volume = {103}, year = {2013}, pages = {182 -}, keywords = {LTER-KNZ}, author = {A. Jumpponen and Lydia H. Zeglin and David, M. and Prestat, E. and Brown, S. and Dvornik, J. and Lothamer, K. and Hettich, R. and Jansson, J. and C. W. Rice and Tringe, S. and Myrold, D.D.} } @article {KNZ001528, title = {Genetic variation and mating success in managed American plains bison}, journal = {Journal of Heredity}, volume = {104}, year = {2013}, pages = {182 -191}, abstract = {

The American plains bison (Bison bison) was pushed to the brink of extinction in the late 1800s but has since rebounded. Less than 5\% of animals currently exist in conservation herds that are critical for maintaining genetic variability. Here, we use 25 microsatellite loci to assess genetic diversity and patterns of mating success over a 3-year period in a managed conservation herd at Konza Prairie Biological Station, Kansas (total number of individuals genotyped = 587). Heterozygosity was comparable to and allelic diversity higher than that in 11 other wild and managed herds for which similar estimates are available. Parentage analyses revealed that males within the oldest age classes (5\–7 years) sired \>90\% of calves over the study period, consistent with a polygynous breeding system. Asymmetries in siring success also were observed within age classes, with the same males enjoying high siring success over multiple seasons. Empirical results of paternity will facilitate future modeling and empirical efforts to determine how demographic factors, population size, and variation in siring success interact to determine the retention (or loss) of genetic diversity in natural and managed herds, thus allowing informed recommendations for management practices and conservation efforts of this symbolic North American species.

}, keywords = {LTER-KNZ}, doi = {10.1093/jhered/ess095}, url = {https://academic.oup.com/jhered/article/104/2/182/802105}, author = {Ungerer, M.C. and Weitekamp, C.A. and Anthony Joern and Towne, G. and J. M. Briggs} } @article {KNZ001488, title = {Global diversity of drought tolerance and grassland climate-change resilience}, journal = {Nature Climate Change}, volume = {3}, year = {2013}, pages = {63 -67}, abstract = {

Drought reduces plant productivity, induces widespread plant mortality and limits the geographic distribution of plant species1, 2, 3, 4, 5, 6, 7. As climates warm and precipitation patterns shift in the future8, 9, understanding the distribution of the diversity of plant drought tolerance is central to predicting future ecosystem function and resilience to climate change10, 11, 12. These questions are especially pressing for the world\’s 11,000 grass species13, which dominate a large fraction of the terrestrial biosphere14, yet are poorly characterized with respect to responses to drought. Here, we show that physiological drought tolerance, which varied tenfold among 426 grass species, is well distributed both climatically and phylogenetically, suggesting most native grasslands are likely to contain a high diversity of drought tolerance. Consequently, local species may help maintain ecosystem functioning in response to changing drought regimes without requiring long-distance migrations of grass species. Furthermore, physiologically drought-tolerant species had higher rates of water and carbon dioxide exchange than intolerant species, indicating that severe droughts may generate legacies for ecosystem functioning. In all, our findings suggest that diverse grasslands throughout the globe have the potential to be resilient to drought in the face of climate change through the local expansion of drought-tolerant species.

}, keywords = {LTER-KNZ, Climate-change ecology, Drought, Grassland ecology}, doi = {10.1038/nclimate1634}, url = {https://www.nature.com/articles/nclimate1634}, author = {Craine, J.M. and Ocheltree, T.W. and Jesse B. Nippert and Towne, E.G. and Skibbe, A.M. and Kembel, S.W. and Fargione, J.E.} } @article {KNZ001615, title = {High-throughput amplicon sequencing of rRNA genes requires a copy number correction to accurately reflect the effects of management practices on soil nematode community structure}, journal = {Molecular Ecology}, volume = {22}, year = {2013}, pages = {5456 -5471}, abstract = {

Nematodes are abundant consumers in grassland soils, but more sensitive and specific methods of enumeration are needed to improve our understanding of how different nematode species affect, and are affected by, ecosystem processes. High-throughput amplicon sequencing is used to enumerate microbial and invertebrate communities at a high level of taxonomic resolution, but the method requires validation against traditional specimen-based morphological identifications. To investigate the consistency between these approaches, we enumerated nematodes from a 25-year field experiment using both morphological and molecular identification techniques in order to determine the long-term effects of annual burning and nitrogen enrichment on soil nematode communities. Family-level frequencies based on amplicon sequencing were not initially consistent with specimen-based counts, but correction for differences in rRNA gene copy number using a genetic algorithm improved quantitative accuracy. Multivariate analysis of corrected sequence-based abundances of nematode families was consistent with, but not identical to, analysis of specimen-based counts. In both cases, herbivores, fungivores and predator/omnivores generally were more abundant in burned than nonburned plots, while bacterivores generally were more abundant in nonburned or nitrogen-enriched plots. Discriminate analysis of sequence-based abundances identified putative indicator species representing each trophic group. We conclude that high-throughput amplicon sequencing can be a valuable method for characterizing nematode communities at high taxonomic resolution as long as rRNA gene copy number variation is accounted for and accurate sequence databases are available.

}, keywords = {LTER-KNZ}, doi = {10.1111/mec.12480}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/mec.12480}, author = {Darby, D.J. and Todd, T.C. and Herman, M.A.} } @article {KNZ001598, title = {Long-term nitrogen amendment alters the diversity and assemblage of soil bacterial communities in tallgrass prairie}, journal = {PLoS ONE}, volume = {8}, year = {2013}, pages = {67884 -}, abstract = {

Anthropogenic changes are altering the environmental conditions and the biota of ecosystems worldwide. In many temperate grasslands, such as North American tallgrass prairie, these changes include alteration in historically important disturbance regimes (e.g., frequency of fires) and enhanced availability of potentially limiting nutrients, particularly nitrogen. Such anthropogenically-driven changes in the environment are known to elicit substantial changes in plant and consumer communities aboveground, but much less is known about their effects on soil microbial communities. Due to the high diversity of soil microbes and methodological challenges associated with assessing microbial community composition, relatively few studies have addressed specific taxonomic changes underlying microbial community-level responses to different fire regimes or nutrient amendments in tallgrass prairie. We used deep sequencing of the V3 region of the 16S rRNA gene to explore the effects of contrasting fire regimes and nutrient enrichment on soil bacterial communities in a long-term (20 yrs) experiment in native tallgrass prairie in the eastern Central Plains. We focused on responses to nutrient amendments coupled with two extreme fire regimes (annual prescribed spring burning and complete fire exclusion). The dominant bacterial phyla identified were Proteobacteria, Verrucomicrobia, Bacteriodetes, Acidobacteria, Firmicutes, and Actinobacteria and made up 80\% of all taxa quantified. Chronic nitrogen enrichment significantly impacted bacterial community diversity and community structure varied according to nitrogen treatment, but not phosphorus enrichment or fire regime. We also found significant responses of individual bacterial groups including Nitrospira and Gammaproteobacteria to long-term nitrogen enrichment. Our results show that soil nitrogen enrichment can significantly alter bacterial community diversity, structure, and individual taxa abundance, which have important implications for both managed and natural grassland ecosystems.

}, keywords = {LTER-KNZ, Bacteria, Biodiversity, Ecosystem functioning, Grasslands, Microbial ecosystems, Plant communities, Ribosomal RNA, Sequence analysis}, doi = {10.1371/journal.pone.0067884}, url = {https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0067884}, author = {Coolon, J.D. and Jones, K.L. and Todd, T.C. and John M. Blair and Herman, M.A.} } @article {KNZ001555, title = {Population origin and genome size do not impact Panicum virgatum (switchgrass) responses to variable precipitation}, journal = {Ecosphere}, volume = {4}, year = {2013}, pages = {37 -}, abstract = {

Population-level adaptation to broad-scale regional climates or within-population variation in genome size of the genetically and phenotypically diverse C4 grass, Panicum virgatum (switchgrass), may influence the responses of this species to future precipitation variability associated with climate change. Therefore, we investigated P. virgatum responses to water variability between natural populations collected across a latitudinal gradient and among individuals spanning a range of genomes sizes within these populations. P. virgatum plants from natural populations originating from Kansas, Oklahoma, and Texas, U.S.A, received frequent, small precipitation events (\“ambient\”) or infrequent, large precipitation events (\“altered\”) to simulate contrasting rainfall variability expected for this region. We measured leaf-level physiology, aboveground biomass and genome size for each individual. Gas exchange rates and aboveground biomass varied significantly by population origin but did not differ by genome size. Altered precipitation treatments reduced leaf-level physiological rates; however this result did not vary by population or genome size. Our results suggest that trait variation in P. virgatum is primarily attributed to population-level adaptation across a latitudinal gradient, not genome size, and that neither population-level adaptation nor genome size may be important predictors of P. virgatum responses to future climatic conditions.

}, keywords = {LTER-KNZ}, doi = {10.1890/ES12-00339.1}, url = {https://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/ES12-00339.1}, author = {O{\textquoteright}Keefe, K. and Tomeo, N. and Jesse B. Nippert and Springer, C.J.} } @article {KNZ001474, title = {Precipitation timing and grazer performance in a tallgrass prairie}, journal = {Oikos}, volume = {122}, year = {2013}, pages = {191 -198}, abstract = {

Changes in precipitation amount and variability have the potential to alter the structure and function of grasslands, but we know little about how changes in the timing of precipitation might affect grasslands. Here, we analyze long-term records from a tallgrass prairie to show that shifts in the timing of precipitation during the growing season have little effect on primary productivity or grass reproduction, but can greatly affect grazer performance. While greater late-season precipitation increases the weight gain of adult and young bison, greater mid-season precipitation decreases their weight gain. In addition, calving rates are lower after years with greater mid-season precipitation and higher after years with greater late-season precipitation. As well-timed drought can actually increase grazer weight gain and reproduction, it will be necessary to generate predictions of within-season distribution of precipitation to successfully forecast future grazer performance.

}, keywords = {LTER-KNZ}, doi = {10.1111/j.1600-0706.2012.20400.x}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1600-0706.2012.20400.x}, author = {Craine, J.M. and Towne, E.G. and Tolleson, D. and Jesse B. Nippert} } @article {KNZ001540, title = {Sensitivity of grassland plant community composition to spatial vs. temporal variation in precipitation}, journal = {Ecology}, volume = {94}, year = {2013}, pages = {1687 -1696}, abstract = {

Climate gradients shape spatial variation in the richness and composition of plant communities. Given future predicted changes in climate means and variability, and likely regional variation in the magnitudes of these changes, it is important to determine how temporal variation in climate influences temporal variation in plant community structure. Here, we evaluated how species richness, turnover, and composition of grassland plant communities responded to interannual variation in precipitation by synthesizing long-term data from grasslands across the United States. We found that mean annual precipitation (MAP) was a positive predictor of species richness across sites, but a positive temporal relationship between annual precipitation and richness was only evident within two sites with low MAP. We also found higher average rates of species turnover in dry sites that in turn had a high proportion of annual species, although interannual rates of species turnover were surprisingly high across all locations. Annual species were less abundant than perennial species at nearly all sites, and our analysis showed that the probability of a species being lost or gained from one year to the next increased with decreasing species abundance. Bray-Curtis dissimilarity from one year to the next, a measure of species composition change that is influenced mainly by abundant species, was insensitive to precipitation at all sites. These results suggest that the richness and turnover patterns we observed were driven primarily by rare species, which comprise the majority of the local species pools at these grassland sites. These findings are consistent with the idea that short-lived and less abundant species are more sensitive to interannual climate variability than longer-lived and more abundant species. We conclude that, among grassland ecosystems, xeric grasslands are likely to exhibit the greatest responsiveness of community composition (richness and turnover) to predicted future increases in interannual precipitation variability. Over the long term, species composition may shift to reflect spatial patterns of mean precipitation; however, perennial-dominated systems will be buffered against rising interannual variation, while systems that have a large number of rare, annual species will show the greatest temporal variability in species composition in response to rising interannual variability in precipitation.

}, keywords = {LTER-KNZ}, doi = {10.1890/12-1006.1}, url = {https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/12-1006.1}, author = {Cleland, E.E. and Scott. L. Collins and Dickson, T.L. and Farrer, E.C. and Gross, K.L. and Gherardi, L.A. and Hallett, L.M. and Hobbs, R.J. and Hsu, J.S. and K.N. Suding and Turnbull, L.} } @article {KNZ001616, title = {Temperature dependant shifts in phenology contribute to the success of exotic species with climate change}, journal = {American Journal of Botany}, volume = {100}, year = {2013}, pages = {1407 -1421}, abstract = {

\• Premise of the study: The study of how phenology may contribute to the assembly of plant communities has a long history in ecology. Climate change has brought renewed interest in this area, with many studies examining how phenology may contribute to the success of exotic species. In particular, there is increasing evidence that exotic species occupy unique phenological niches and track climate change more closely than native species. \• Methods: Here, we use long-term records of species\’ first flowering dates from five northern hemisphere temperate sites (Chinnor, UK and in the United States, Concord, Massachusetts; Fargo, North Dakota; Konza Prairie, Kansas; and Washington, D.C.) to examine whether invaders have distinct phenologies. Using a broad phylogenetic framework, we tested for differences between exotic and native species in mean annual flowering time, phenological changes in response to temperature and precipitation, and longer-term shifts in first flowering dates during recent pronounced climate change (\“flowering time shifts\”). \• Key results: Across North American sites, exotic species have shifted flowering with climate change while native species, on average, have not. In the three mesic systems, exotic species exhibited higher tracking of interannual variation in temperature, such that flowering advances more with warming, than native species. Across the two grassland systems, however, exotic species differed from native species primarily in responses to precipitation and soil moisture, not temperature. \• Conclusions: Our findings provide cross-site support for the role of phenology and climate change in explaining species\’ invasions. Further, they support recent evidence that exotic species may be important drivers of extended growing seasons observed with climate change in North America.

}, keywords = {LTER-KNZ, flowering time, introduced species, invasion biology, non-native species, North American prairies, plant phenology, temperate grasslands}, doi = {10.3732/ajb.1200478}, url = {https://bsapubs.onlinelibrary.wiley.com/doi/full/10.3732/ajb.1200478}, author = {Wolkovich, E.M. and Davies, T.J. and Schaefer, H. and Cleland, E.E. and Cook, B.I. and Travers, S.E. and Willis, C.G. and Davis, C.C.} } @article {KNZ001462, title = {Community traitscape of foliar nitrogen isotopes reveals N availabiity patterns in a tallgrass prairie}, journal = {Plant and Soil}, volume = {356}, year = {2012}, pages = {395 -403}, abstract = {

Background and aims Nutrients are important determinants of community assembly, yet the roles they play in structuring plant communities are still poorly understood. One inferential approach to understanding how environmental factors structure plant communities is examining the distribution of key functional traits among species of a community\—a community traitscape. Methods To better understand how nitrogen (N) and water availability structure grasslands, we measured N concentrations and isotope ratios for 366 herbaceous species in a mesic N-limited temperate grassland, Konza Prairie. We also compared foliar N concentrations and N isotopes between Konza species and a global dataset. Results Species that had either high foliar N concentrations or high δ15NL were not necessarily more or less abundant on the landscape nor more or less likely to be found in uplands, grazed areas, or burned areas. Apparently there are unique hot spots of high N availability at Konza and the typical non-Fabaceae Konza species occupies sites with greater N availability than found globally. Conclusions Although nascent, the Konza traitscapes suggest that plant diversity in nutrient-limited communities might be strongly dependent on high-nutrient availability sites that enable high-fertility species to persist in a matrix of low nutrient availability.

}, keywords = {LTER-KNZ, Community assembly, disturbance, Grasslands, Isotopes, Konza Prairie, Resource limitation}, doi = {10.1007/s11104-012-1141-7}, url = {https://link.springer.com/article/10.1007\%2Fs11104-012-1141-7}, author = {Craine, J.M. and Towne, E.G. and Ocheltree, T.W. and Jesse B. Nippert} } @article {KNZ001623, title = {The effect of experimental warming and precipitation change on proteolytic enzyme activity: positive feedbacks to nitrogen availability are not universal}, journal = {Global Change Biology}, volume = {18}, year = {2012}, pages = {2617 -2625}, abstract = {

Nitrogen regulates the Earth\&$\#$39;s climate system by constraining the terrestrial sink for atmospheric CO2. Proteolytic enzymes are a principal driver of the within-system cycle of soil nitrogen, yet there is little to no understanding of their response to climate change. Here, we use a single methodology to investigate potential proteolytic enzyme activity in soils from 16 global change experiments. We show that regardless of geographical location or experimental manipulation (i.e., temperature, precipitation, or both), all sites plotted along a single line relating the response ratio of potential proteolytic activity to soil moisture deficit, the difference between precipitation and evapotranspiration. In particular, warming and reductions in precipitation stimulated potential proteolytic activity in mesic sites \– temperate and boreal forests, arctic tundra \– whereas these manipulations suppressed potential activity in dry grasslands. This study provides a foundation for a simple representation of the impacts of climate change on a central component of the nitrogen cycle.

}, keywords = {LTER-KNZ}, doi = {10.1111/j.1365-2486.2012.02685.x}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2486.2012.02685.x}, author = {Brozostek, E.R. and John M. Blair and Dukes, J.S. and Frey, S.D. and Hobbie, S.E. and Melillo, J.M. and Mitchell, R.J. and Pendall, E.S. and P.B. Reich and Shaver, G.R. and Stefanskii, A. and Tjoelker, M.G. and Finzi, A.C.} } @article {KNZ001513, title = {The effect of precipitation events on inorganic carbon in soil and shallow groundwater, Konza Prairie LTER Site, NE Kansas, USA}, journal = {Applied Geochemistry}, volume = {27}, year = {2012}, pages = {2356 -2369}, abstract = {

Monthly sampling for 1 year at the Konza Prairie LTER (Long-Term Ecological Research) Site in northeastern Kansas shows a connection between the annual cycles of CO2 in soil air and shallow groundwater DIC (dissolved inorganic C). Soil air CO2 reached 6\–7\% in July to mid-August, when moisture was not limiting to soil respiration. Following the annual maximum there was a sequential decrease in CO2 in three soil horizons to less than 0.5\% because of moisture deficiency in the late summer and temperature decline in the fall and winter. Groundwater pCO2 reached its maximum of 5\% in October; the lag-time of 2\–3 months may correspond to the travel time of soil-generated CO2 to the water table. The time-variable CO2 caused an annual carbonate-mineral saturation cycle, intensifying limestone dissolution and DIC production when CO2 was high. The C flux depended on respiration and rainfall regimes, and had two main pathways. Transport of soil CO2 in the dissolved form with diffuse flow of recharge water was the most effective during the growing season so long as soil moisture was present. Downward movement of gaseous CO2 and equilibration with groundwater at the water table was favorable in July to August. Storm rainfall events recharged the aquifer within a few hours through preferential flow and stream\–groundwater interaction, resulting in dilution of groundwater rather than forcing entrapped CO2 downward. Calculated C flux from the unsaturated zone to the unconfined aquifer in the monitoring period was 0.26 \± 0.03 M/m2/a of C, which is less than 1\% of the CO2 that is released by soil to the atmosphere via efflux. However, meteoric precipitation was only 72\% of average annual precipitation during the study period, so this study represents dry-condition flux. In addition, increased respiration rates due to warming of the atmosphere have the potential to cause a higher C flux to the saturated zone, intensifying weathering and groundwater acidification, so that further study is suggested.

}, keywords = {LTER-KNZ}, doi = {10.1016/j.apgeochem.2012.07.008}, url = {https://www.sciencedirect.com/science/article/pii/S0883292712001734?via\%3Dihub}, author = {Tsypin, M. and G. L. Macpherson} } @article {KNZ001446, title = {Flowering phenology as a functional trait in a tallgrass prairie}, journal = {New Phytologist}, volume = {193}, year = {2012}, pages = {673 -682}, abstract = {

\•The timing of flowering is a critical component of the ecology of plants and has the potential to structure plant communities. Yet, we know little about how the timing of flowering relates to other functional traits, species abundance, and average environmental conditions. \•Here, we assessed first flowering dates (FFDs) in a North American tallgrass prairie (Konza Prairie) for 431 herbaceous species and compared them with a series of other functional traits, environmental metrics, and species abundance across ecological contrasts. \•The pattern of FFDs among the species of the Konza grassland was shaped by local climate, can be linked to resource use by species, and patterns of species abundance across the landscape. Peak FFD for the community occurred when soils were typically both warm and wet, while relatively few species began flowering when soils tended to be the driest. Compared with late-flowering species, species that flowered early had lower leaf tissue density and were more abundant on uplands than lowlands. \•Flowering phenology can contribute to the structuring of grassland communities, but was largely independent of most functional traits. Therefore, selection for flowering phenology may be independent of general resource strategies.

}, keywords = {LTER-KNZ}, doi = {10.1111/j.1469-8137.2011.03953.x}, url = {https://nph.onlinelibrary.wiley.com/doi/full/10.1111/j.1469-8137.2011.03953.x}, author = {Craine, J.M. and Wolkovich, E.M. and Towne, E.G. and Kembel, S.W.} } @article {KNZ001471, title = {Maternal allocation and offspring characteristics in Bison}, journal = {Ecological Applications}, volume = {22}, year = {2012}, pages = {1628 -1639}, abstract = {

Parental allocation strategies are of profound interest in life history because they directly impact offspring fitness and therefore are highly valuable for understanding population dynamics and informing management decisions. Yet, numerous questions about reproductive allocation patterns for wild populations of large mammals remain unanswered because of the challenges for measuring allocation in the wild. Using a nine-year longitudinal data set on life-history traits of mother\–calf bison pairs, we identified sources of variation in relative maternal allocation (calf mass ratio on mother mass) and assessed the occurrence of reproductive costs associated with differential maternal allocation. We found that heavy mothers provided a lower allocation but still produced heavier calves than light mothers. Older females produced lighter calves and tended to decrease allocation as they aged, supporting the occurrence of reproductive senescence. Mothers that had produced a calf the previous year produced lighter calves and allocated less than mothers that did not lactate the previous year, revealing reproductive costs. However, greater maternal allocation did not reduce the probability of breeding in successive years, and the amount of allocation provided by a mother was positively correlated among the offspring she produced, illustrating individual heterogeneity. Although life-history studies are usually classified as either supporting costs of reproduction or individual quality, our study demonstrates that these contrasting evolutionary forces can shape variation within a single trait. Our work illustrates that many processes can coevolve within a population, emphasizing the need to integrate multiple concepts to better understand the evolution of life-history traits. With regard to management of bison herds, if the goal of culling programs is to select for animals with the best performance, this research suggests that managers should account for the condition and previous reproductive status of mothers when taking culling decisions on juvenile bison.

}, keywords = {LTER-KNZ}, doi = {10.1890/11-2181.1}, url = {https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/11-2181.1}, author = {Hamel, S. and Craine, J.M. and Towne, E.G.} } @mastersthesis {KNZ001557, title = {A mycorrhizal community is unresponsive to simulated future precipitation variability}, volume = {MS Thesis}, year = {2012}, school = {St. Joseph{\textquoteright}s University}, type = {M.S. Thesis}, address = {Philadelphia, PA}, keywords = {LTER-KNZ}, author = {Tomeo, N.J.} } @article {KNZ001469, title = {The roles of shifting and filtering in generating community-level flowering phenology}, journal = {Ecography}, volume = {35}, year = {2012}, pages = {1033 -1038}, abstract = {

Plant phenologies are key components of community assembly and ecosystem function, yet we know little about how phenological patterns differ among ecosystems. Community-level phenological patterns may be driven by the filtering of species into communities based on their phenology or by intraspecific responses to local conditions that shift when species flower. To understand the relative roles of filtering and shifting on community-level phenological patterns we compared patterns of first flowering dates (FFD) for herbaceous species at Konza Prairie, KS, USA with those from the colder Fargo, ND, USA area and from Chinnor, England, which has a less continental climate. Comparing patterns of FFD supports that Konza\&$\#$39;s flowering patterns are potentially influenced both by filtering species that flower early in the growing season and by phenological shifting. Konza species flowering dates were earlier in the spring and later in the fall compared to Fargo, but were not shifted compared to Chinnor, which had a unique suite of early-flowering species. In all, comparing flowering phenology among three sites reveals that intraspecific responses to climate can generate phenological shifts that compress or stretch community-level phenological patterns, while novel niches in phenological space can also alter community-level patterns. Community flowering patterns related to climate suggest that climatic warming has the potential to further distribute flowering of the Konza flora over a longer period, but also could further open it to introductions of non-native species that have evolved to flower early in the season.

}, keywords = {LTER-KNZ}, doi = {10.1111/j.1600-0587.2012.07625.x}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1600-0587.2012.07625.x}, author = {Craine, J.M. and Wolkovich, E.M. and Towne, E.G.} } @article {KNZ001483, title = {Several grassland soil nematodes species are insensitive to RNA-mediated interference}, journal = {Journal of Nematology}, volume = {44}, year = {2012}, pages = {92 -101}, abstract = {

Phenotypic analysis of defects caused by RNA mediated interference (RNAi) in Caenorhabditis elegans has proven to be a powerful tool for determining gene function. In this study we investigated the effectiveness of RNAi in four non-model grassland soil nematodes, Oscheius sp FVV-2., Rhabditis sp, Mesorhabditis sp., and Acrobeloides sp. In contrast to reference experiments performed using C. elegans and Caenorhabditis briggsae, feeding bacteria expressing dsRNA and injecting dsRNA into the gonad did not produce the expected RNAi knockdown phenotypes in any of the grassland nematodes. Quantitative reverse-transcribed PCR (qRT-PCR) assays did not detect a statistically significant reduction in the mRNA levels of endogenous genes targeted by RNAi in Oscheius sp., and Mesorhabditis sp. From these studies we conclude that due to low effectiveness and inconsistent reproducibility, RNAi knockdown phenotypes in non-Caenorhabditis nematodes should be interpreted cautiously.

}, keywords = {LTER-KNZ}, url = {https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3593264/}, author = {Wheeler, D. and Darby, B.J. and Todd, T.C. and Herman, M.A.} } @article {KNZ001506, title = {Tracking C and N flows through microbial biomass with increased soil moisture variability}, journal = {Soil Biology \& Biochemistry}, volume = {49}, year = {2012}, pages = {11 -22}, abstract = {

Changes in soil moisture with cycles of soil wetting and drying are associated with shifts in osmotic potentials that can induce physiological stress for microbial communities. These instances of soil moisture stress can be of sufficient magnitude to alter flows of C and N at an ecosystem scale. In this study we manipulated the duration and severity of soil moisture stress and disturbance in grassland soils from four sites along a precipitation gradient. After subjecting soils to a two-month long incubation under two different wetting-drying regimes, one of high and one of low stress and disturbance, we moistened soils with 13C- and 15N-labeled glycine solution to trace C and N though the soil and its microbial communities as they dried. Contrary to our predictions, we found evidence for preferential use of N-free osmolytes with increased soil moisture stress in soils from the mesic end of the precipitation gradient. Soils from the western, semi-arid end of the gradient were less sensitive to soil moisture stress and did not differ in N demand under high and low stress. Specific respiration rates were higher in all soils under greater soil moisture stress immediately after re-wetting, then returned to levels equal to or below rates in soils under low soil moisture stress regimes. Nitrification outpaced denitrification processes in soils under the highest levels of soil moisture stress. These results suggest increases in both soil CO2 release and N losses as stress induced by greater soil moisture variability increases in relatively mesic grassland systems, a predicted consequence of climate change in this region.

}, keywords = {LTER-KNZ, Carbon use efficiency, Climate change, grassland, Precipitation regime, Soil carbon, Soil moisture variability, Soil nitrogen}, doi = {10.1016/j.soilbio.2012.01.030}, url = {https://www.sciencedirect.com/science/article/abs/pii/S0038071712000521?via\%3Dihub}, author = {Tiemann, L.K. and Billings, S.A.} } @article {KNZ001757, title = {Changes in variability of soil moisture alter microbial community C and N resource use}, journal = {Soil Biology and Biochemistry}, volume = {43}, year = {2011}, pages = {1837 - 1847}, abstract = {

Grassland ecosystems contain ~12\% of global soil organic carbon (C) stocks and are located in regions where global climate change will likely alter the timing and size of precipitation events, increasing soil moisture variability. In response to increased soil moisture variability and other forms of stress, microorganisms can induce ecosystem-scale alterations in C and N cycling processes through alterations in their function. We explored the influence of physiological stress on microbial communities by manipulating moisture variability in soils from four grassland sites in the Great Plains, representing a precipitation gradient of 485-1003 mm y-1. Keeping water totals constant, we manipulated the frequency and size of water additions and dry down periods in these soils by applying water in two different, two-week long wetting-drying cycles in a 72-day laboratory incubation. To assess the effects of the treatments on microbial community function, we measured C mineralization, N dynamics, extracellular enzyme activities (EEA) and a proxy for substrate use efficiency. In soils from all four sites undergoing a long interval (LI) treatment for which added water was applied once at the beginning of each two-week cycle, 1.4-2.0 times more C was mineralized compared to soils undergoing a short interval (SI) treatment, for which four wetting events were evenly distributed over each two-week cycle. A proxy for carbon use efficiency (CUE) suggests declines in this parameter with the greater soil moisture stress imposed in LI soils from all four different native soil moisture regimes. A decline in CUE in LI soils may have been related to an increased effort by microbes to obtain N-rich organic substrates for use as protection against osmotic shock, consistent with EEA data. These results contrast with similar in situ studies of response to increased soil moisture variability and may indicate divergent autotrophic vs. heterotrophic responses to increased moisture variability. Increases in microbial N demand and decreases in microbial CUE with increased moisture variability observed in this study, regardless of the soils\&$\#$39; site of origin, imply that these systems may experience enhanced heterotrophic CO2 release and declines in plant-available N with climate change. This has particularly important implications for C budgets in these grasslands when coupled with the declines in net primary productivity reported in other studies as a result of increases in precipitation variability across the region.

}, keywords = {LTER-KNZ}, doi = {10.1016/j.soilbio.2011.04.020}, url = {https://www.sciencedirect.com/science/article/abs/pii/S0038071711001787?via\%3Dihub}, author = {Tiemann, L.K. and Billings, S.A.} } @article {KNZ001431, title = {Cross-stream comparison of substrate-specific denitrification potential}, journal = {Biogeochemistry}, volume = {104}, year = {2011}, pages = {381 -392}, abstract = {

Headwater streams have a demonstrated ability to denitrify a portion of their nitrate (NO3 \−) load but there has not been an extensive consideration of where in a stream this process is occurring and how various habitats contribute to total denitrification capability. As part of the Lotic Intersite Nitrogen Experiment II (LINX II) we measured denitrification potential in 65 streams spanning eight regions of the US and draining three land-use types. In each stream, potential denitrification rates were measured in common substrate types found across many streams as well as locations unique to particular streams. Overall, habitats from streams draining urban and agricultural land-uses showed higher potential rates of denitrification than reference streams draining native vegetation. This difference among streams was probably driven by higher ambient nitrate concentrations found in urban or agricultural streams. Within streams, sandy habitats and accumulations of fine benthic organic matter contributed more than half of the total denitrification capacity (mg N removed m\−2 h\−1). A particular rate of potential denitrification per unit area could be achieved either by high activity per unit organic matter or lower activities associated with larger standing stocks of organic matter. We found that both small patches with high rates (hot spots) or more widespread but less active areas (cool matrix) contributed significantly to whole stream denitrification capacity. Denitrification estimated from scaled-up denitrification enzyme assay (DEA) potentials were not always dramatically higher than in situ rates of denitrification measured as 15N gas generation following 24-h 15N\–NO3 tracer additions. In general, headwater streams draining varying land-use types have significant potential to remove nitrate via denitrification and some appear to be functioning near their maximal capacity.

}, keywords = {LTER-KNZ, Comparative, Comparison of potential with realized denitrification, DEA, denitrification, stream, Substrate-specific}, doi = {10.1007/s10533-010-9512-8}, url = {https://link.springer.com/article/10.1007\%2Fs10533-010-9512-8}, author = {Findlay, S.E.G. and Mulholland, P.J. and Hamilton, S. and Tank, J. and Bernot, M. and Burgin, A.J. and Crenshaw, C. and W. K. Dodds and Grimm, N. and W.H. McDowell and Potter, J. and Sobota, D.} } @mastersthesis {KNZ001487, title = {Dissolved inorganic carbon in soil and shallow groundwater, Konza Prairie LTER Site, NE Kansas, USA}, volume = {MS Thesis}, year = {2011}, school = {University of Kansas}, type = {M.S. Thesis}, address = {Lawrence, KS}, abstract = {

Sources and seasonal trends of dissolved inorganic carbon (DIC) in a shallow limestone aquifer were studied for 1 year at the Konza Prairie LTER (Long-Term Ecological Research) Site in northeastern Kansas, from spring 2010 to spring 2011. Annual cycles of soil air CO2, groundwater DIC, and isotope characteristics showed a strong dependency on weather conditions and soil respiration. Soil air CO2 reached its annual maximum in the middle of the growing season, when moisture was not limiting to soil respiration. Following the maximum, the CO2 decreased because of moisture deficiency in the late summer and temperature decline in the fall and winter. The decrease began first in the shallowest part of the soil and last in the deepest part. Groundwater CO2 reached its annual maximum in October; this lag-time between the soil and groundwater CO2 maxima of 2-3 months may correspond to the travel time of soil-generated CO2 to the water table. The time-variable CO2 caused an annual carbonate-mineral saturation cycle, intensifying limestone dissolution, thus soil CO2 and carbonate minerals are the two main sources of DIC in soil and groundwater. The stable carbon isotope composition of soil air CO2 and DIC exhibited primarily C4 plant signature and were similar to that of soil organic matter, suggesting that both root and bacterial respiration are sources of CO2. DIC was enriched in 7-10 per mil PDB relative to the CO2 source due to isotope fractionation in a system open to soil CO2; the enrichment was smallest under highest pCO2. For this reason, d13CDIC was out of phase with DIC, the lightest in the late growing season. The carbon flux from the unsaturated zone to the unconfined aquifer during the year was variable depending on respiration and precipitation regimes, and had two main pathways. Transport of soil CO2 in the dissolved form with diffuse flow of recharge water was the most effective during the entire growing season. Downward movement of gaseous CO2 and equilibration with groundwater at the water table was possible in July to August. Storm rainfall events rapidly recharged the aquifer through preferential flow and stream-groundwater interaction. Rather than forcing soil gases downward because of water-saturated pores, the main effect of these events was dilution of groundwater. The calculated flux was about 0.3 M/m2/yr of C, which is less than 1\% of the CO2 that is released by soil to the atmosphere via efflux. However, the climate prediction of increased respiration rates, temperature, and frequency of extreme rainfall events has the potential to cause higher carbon flux to the saturated zone, intensifying weathering and groundwater acidification.

}, keywords = {LTER-KNZ}, url = {http://hdl.handle.net/1808/10386}, author = {Tsypin, Mikhail} } @article {KNZ001367, title = {Functional consequences of climate-change induced plant species loss in a tallgrass prairie}, journal = {Oecologia}, volume = {165}, year = {2011}, pages = {1109 -1117}, abstract = {

Future climate change is likely to reduce the floristic diversity of grasslands. Yet the potential consequences of climate-induced plant species losses for the functioning of these ecosystems are poorly understood. We investigated how climate change might alter the functional composition of grasslands for Konza Prairie, a diverse tallgrass prairie in central North America. With species-specific climate envelopes, we show that a reduction in mean annual precipitation would preferentially remove species that are more abundant in the more productive lowland positions at Konza. As such, decreases in precipitation could reduce productivity not only by reducing water availability but by also removing species that inhabit the most productive areas and respond the most to climate variability. In support of this prediction, data on species abundance at Konza over 16 years show that species that are more abundant in lowlands than uplands are preferentially reduced in years with low precipitation. Climate change is likely to also preferentially remove species from particular functional groups and clades. For example, warming is forecast to preferentially remove perennials over annuals as well as Cyperaceae species. Despite these predictions, climate change is unlikely to unilaterally alter the functional composition of the tallgrass prairie flora, as many functional traits such as physiological drought tolerance and maximum photosynthetic rates showed little relationship with climate envelope parameters. In all, although climatic drying would indirectly alter grassland productivity through species loss patterns, the insurance afforded by biodiversity to ecosystem function is likely to be sustained in the face of climate change.

}, keywords = {LTER-KNZ, biogeography, Climate change, Functional traits, Grasslands, Konza Prairie}, doi = {10.1007/s00442-011-1938-8}, url = {https://link.springer.com/article/10.1007\%2Fs00442-011-1938-8}, author = {Craine, J.M. and Jesse B. Nippert and Towne, E.G. and Tucker, S. and Kembel, S.W. and Skibbe, A.M. and McLauchlan, K.K.} } @article {KNZ001395, title = {Genomic and resistance gene homolog diversity of the dominant tallgrass prairie species across the U.S. Great Plains precipitation gradient}, journal = {PLoS ONE}, volume = {6:e17641}, year = {2011}, abstract = {

Background Environmental variables such as moisture availability are often important in determining species prevalence and intraspecific diversity. The population genetic structure of dominant plant species in response to a cline of these variables has rarely been addressed. We evaluated the spatial genetic structure and diversity of Andropogon gerardii populations across the U.S. Great Plains precipitation gradient, ranging from approximately 48 cm/year to 105 cm/year. Methodology/Principal Findings Genomic diversity was evaluated with AFLP markers and diversity of a disease resistance gene homolog was evaluated by PCR-amplification and digestion with restriction enzymes. We determined the degree of spatial genetic structure using Mantel tests. Genomic and resistance gene homolog diversity were evaluated across prairies using Shannon\&$\#$39;s index and by averaging haplotype dissimilarity. Trends in diversity across prairies were determined using linear regression of diversity on average precipitation for each prairie. We identified significant spatial genetic structure, with genomic similarity decreasing as a function of distance between samples. However, our data indicated that genome-wide diversity did not vary consistently across the precipitation gradient. In contrast, we found that disease resistance gene homolog diversity was positively correlated with precipitation. Significance Prairie remnants differ in the genetic resources they maintain. Selection and evolution in this disease resistance homolog is environmentally dependent. Overall, we found that, though this environmental gradient may not predict genomic diversity, individual traits such as disease resistance genes may vary significantly.

}, keywords = {LTER-KNZ, Amplified fragment length polymorphism, Cloning, Hexaploidy, Maize, Plant genomics, Plant pathology, Ploidy, Population genetics}, doi = {10.1371/journal.pone.0017641}, url = {https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0017641}, author = {Rouse, M.N. and Saleh, A.A. and Seck, A. and Keeler, K.H. and Travers, S.E. and Hulbert, S.H. and Garrett, K.A.} } @article {KNZ001360, title = {Nitrous oxide emission from denitrification in stream and river networks}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {108}, year = {2011}, pages = {214 -219}, abstract = {

Nitrous oxide (N2O) is a potent greenhouse gas that contributes to climate change and stratospheric ozone destruction. Anthropogenic nitrogen (N) loading to river networks is a potentially important source of N2O via microbial denitrification that converts N to N2O and dinitrogen (N2). The fraction of denitrified N that escapes as N2O rather than N2 (i.e., the N2O yield) is an important determinant of how much N2O is produced by river networks, but little is known about the N2O yield in flowing waters. Here, we present the results of whole-stream 15N-tracer additions conducted in 72 headwater streams draining multiple land-use types across the United States. We found that stream denitrification produces N2O at rates that increase with stream water nitrate (NO3\−) concentrations, but that \<1\% of denitrified N is converted to N2O. Unlike some previous studies, we found no relationship between the N2O yield and stream water NO3\−. We suggest that increased stream NO3\− loading stimulates denitrification and concomitant N2O production, but does not increase the N2O yield. In our study, most streams were sources of N2O to the atmosphere and the highest emission rates were observed in streams draining urban basins. Using a global river network model, we estimate that microbial N transformations (e.g., denitrification and nitrification) convert at least 0.68 Tg\·y\−1 of anthropogenic N inputs to N2O in river networks, equivalent to 10\% of the global anthropogenic N2O emission rate. This estimate of stream and river N2O emissions is three times greater than estimated by the Intergovernmental Panel on Climate Change. Humans have more than doubled the availability of fixed nitrogen (N) in the biosphere, particularly through the production of N fertilizers and the cultivation of N-fixing crops (1). Increasing N availability is producing unintended environmental consequences including enhanced emissions of nitrous oxide (N2O), a potent greenhouse gas (2) and an important cause of stratospheric ozone destruction (3). The Intergovernmental Panel on Climate Change (IPCC) estimates that the microbial conversion of agriculturally derived N to N2O in soils and aquatic ecosystems is the largest source of anthropogenic N2O to the atmosphere (2). The production of N2O in agricultural soils has been the focus of intense investigation (i.e., \>1,000 published studies) and is a relatively well constrained component of the N2O budget (4). However, emissions of anthropogenic N2O from streams, rivers, and estuaries have received much less attention and remain a major source of uncertainty in the global anthropogenic N2O budget. Microbial denitrification is a large source of N2O emissions in terrestrial and aquatic ecosystems. Most microbial denitrification is a form of anaerobic respiration in which nitrate (NO3\−, the dominant form of inorganic N) is converted to dinitrogen (N2) and N2O gases (5). The proportion of denitrified NO3\− that is converted to N2O rather than N2 (hereafter referred to as the N2O yield and expressed as the mole ratio) partially controls how much N2O is produced via denitrification (6), but few studies provide information on the N2O yield in streams and rivers because of the difficulty of measuring N2 and N2O production in these systems. Here we report rates of N2 and N2O production via denitrification measured using whole-stream 15NO3\−-tracer experiments in 72 headwater streams draining different land-use types across the United States. This project, known as the second Lotic Intersite Nitrogen eXperiment (LINX II), provides unique whole-system measurements of the N2O yield in streams. Although N2O emission rates have been reported for streams and rivers (7, 8), the N2O yield has been studied mostly in lentic freshwater and marine ecosystems, where it generally ranges between 0.1 and 1.0\%, although yields as high as 6\% have been observed (9). These N2O yields are low compared with observations in soils (0\–100\%) (10), which may be a result of the relatively lower oxygen (O2) availability in the sediments of lakes and estuaries. However, dissolved O2 in headwater streams is commonly near atmospheric equilibrium and benthic algal biofilms can produce O2 at the sediment\–water interface, resulting in strong redox gradients more akin to those in partially wetted soils. Thus, streams may have variable and often high N2O yields, similar to those in soils (11). The N2O yield in headwater streams is of particular interest because much of the NO3\− input to rivers is derived from groundwater upwelling into headwater streams. Furthermore, headwater streams compose the majority of stream length within a drainage network and have high ratios of bioreactive benthic surface area to water volume (12).

}, keywords = {LTER-KNZ}, doi = {10.1073/pnas.1011464108}, url = {https://www.pnas.org/content/108/1/214}, author = {Beaulieu, J.K. and Tank, J.L. and Hamilton, S.K. and Wollheim, W.M. and Hall, R.O. and Mulholland, P.J. and Peterson, B.J. and L.R. Ashkenas and Cooper, L.W. and Dahm, C.N. and W. K. Dodds and Grimm, N.B. and Johnson, S.L. and W.H. McDowell and Poole, G.C. and Valett, H.M. and Arango, C.P. and Bernot, M.J. and Burgin, A.J. and Crenshaw, C. and Helton, A.M. and Johnson, L. and O{\textquoteright}Brien, J.M. and Potter, J.D. and Sheibley, R.W. and Sobota, D.J. and Thomas, S.M.} } @article {KNZ001389, title = {Physiological drought tolerance and the structuring of tallgrass assemblages}, journal = {Ecosphere}, volume = {2}, year = {2011}, pages = {48 -}, abstract = {

Drought is a defining characteristic of many grasslands worldwide. Yet we have little understanding of how drought structures grassland communities and the degree to which physiological drought tolerance advantages plants in grasslands. We characterized physiological drought tolerance (Ψcrit) for a large number of species in a mesic grassland community (Konza Prairie, KS, USA). We then examined the relationships between Ψcrit and a number of other key functional traits, and tested whether physiological tolerance of drought underlay success across a number of ecological contrasts\—topographic position, burn frequency, and grazing\—with 17 years of abundance data. Physiological drought tolerance of Konza species covered almost the full range known to plants globally. Consistently, physiologically drought-tolerant species had thin roots, while associations with other traits were inconsistent across functional groups. In this mesic grassland, physiological drought tolerance appears to increase the abundance of plants in xeric uplands, but does not in the mesic lowlands. Physiological drought tolerance did not alter species responses to changes in burning or grazing. In contrast to Ψcrit, species with high root tissue density were more abundant in uplands and lowlands than species with low root tissue density largely irrespective of grazing or burning regimes. In all, drought appears to have a limited role in structuring the Konza plant community. As such, more severe or frequent droughts in the region would likely restructure the Konza plant community in ways that are currently not observable.

}, keywords = {LTER-KNZ}, doi = {10.1890/ES11-00023.1}, url = {https://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/ES11-00023.1}, author = {Tucker, S.S. and Craine, J.M. and Jesse B. Nippert} } @phdthesis {KNZ001421, title = {Soil microbial community carbon and nitrogen dynamics with altered precipitation regimes and substrate availability}, volume = {PhD Dissertation}, year = {2011}, school = {University of Kansas}, type = {Ph.D. Thesis}, address = {Lawrence, KS}, abstract = {

Understanding the nature and extent of the feedback between soil microorganisms and ecosystem processes is of great concern as we are faced with multiple elements of global environmental change. In this dissertation, I explore how anthropogenically induced environmental changes affect soil microorganisms\&$\#$39; resource use, and how, in turn, changes in microbial resource use alters ecosystem processes. These explorations were conducted in grassland systems, which contain 12\% of global soil carbon (C) stocks and can serve as large C sources or sinks depending on environmental conditions such as nitrogen (N) availability and precipitation regimes. Nitrogen availability in grasslands can control plant primary productivity as well as rates soil organic matter decomposition and the fate of soil organic C. In grassland systems undergoing N addition through fertilization, resource inputs to soils increase in both quality and quantity. In Chapter 1, I investigate the fate of enhanced biomass inputs due to N addition by determining the direct and indirect effects of N addition on the activity of the soil microbial decomposers. Through measurement of extracellular enzyme activities and isotopic analysis of the microbial biomass relative to substrate sources, I found enhanced mineralization of newly incorporated soil organic C with N addition. This increase in soil C break down was associated indirectly with N addition through increases in plant litter quality and not directly with increased soil N availability. These results suggest that increased biomass input resulting from N addition does not necessarily result in increased soil C accrual. Climate change in the Great Plains region will likely cause increases in drought severity and precipitation event size with little change in annual precipitation totals. Precipitation events, particularly those following periods of drought, can create large flushes of resources for microbial communities, but these same pulses also can cause high levels of physiological stress and disturbance. When faced with increased soil moisture stress and re-wetting disturbance, microorganisms must accumulate and release protective osmolytes. The acquisition and release of protective osmolytes, apparently of sufficient magnitude to influence ecosystem level N and C fluxes, makes understanding the mechanisms behind these fluxes critical for predicting not only microbial community responses to global change, but ecosystem responses as well. In Chapter 2, 3 and 4, I use soils from four locations across the Great Plains precipitation gradient in a combination of laboratory and in situ soil incubations to explore the effects of soil moisture stress on flows of C and N though the microbial biomass. In Chapter 2, I focus on links between soil moisture stress and resource use efficiency by manipulating the frequency and magnitude of soil wetting and drying cycles in laboratory soil incubations. As soil moisture stress was increased with longer drought intervals and larger water pulse events, I saw a decline in C use efficiency and a 360 - 4800\% increase in net N mineralization in soils from four sites along the Great Plains precipitation gradient. In Chapter 3, I employed the use of stable isotopes at the end of a similar incubation, to trace the C and N during a soil wetting-drying cycle. In this study I found that increased levels of soil moisture stress shifted microbial preference from N-rich protective osmolytes to N-free osmolytes. I also found that soils from the mesic end of the precipitation gradient were more sensitive to changes in soil moisture stress than soils from the semi-arid end of the gradient and that nitrification appeared to be less sensitive than denitrification, leading to increased soil nitrate concentrations and a decoupling in the N cycle. Finally, in Chapter 4, I reciprocally transferred soils between four study sites along the precipitation gradient and allowed them to incubate in situ for 1.5 and 2.5 y. After collection I assessed nitrification and denitrification potentials and the abundance of functional genes associated with these processes. I compared effects of both the initial community composition and the change in environment on the process rates. I found that as soil moisture stress increased across the precipitation gradient, nitrification potential decreased and nitrification functional gene abundance increased. Depending on soil origin, denitrifiers were either sensitive, resistant or functionally redundant after 1.5 y of altered precipitation regimes. In contrast, after 2.5 y denitrifiers in soils of all origins exhibited declines in process rates and functional gene abundance with increased soil moisture stress. Overall, I found that microbial communities are sensitive to environmental change, and as these communities shift in structure and function C and N cycling in these grasslands is altered. In particular, the perturbations explored in this dissertation, N addition and climate change, may induce increased rates of C release and N loss from these grassland soils.

}, keywords = {LTER-KNZ}, url = {http://hdl.handle.net/1808/7689}, author = {Tiemann, L.} } @article {KNZ001399, title = {Species abundance distributions and richness estimations in fungal metagenomics {\textendash} lessons learned from community ecology}, journal = {Molecular Ecology}, volume = {20}, year = {2011}, pages = {275 -285}, abstract = {

Results of diversity and community ecology studies strongly depend on sampling depth. Completely surveyed communities follow log-normal distribution, whereas power law functions best describe incompletely censused communities. It is arguable whether the statistics behind those theories can be applied to voluminous next generation sequencing data in microbiology by treating individual DNA sequences as counts of molecular taxonomic units (MOTUs). This study addresses the suitability of species abundance models in three groups of plant-associated fungal communities \– phyllosphere, ectomycorrhizal and arbuscular mycorrhizal fungi. We tested the impact of differential treatment of molecular singletons on observed and estimated species richness and species abundance distribution models. The arbuscular mycorrhizal community of 48 MOTUs was exhaustively sampled and followed log-normal distribution. The ectomycorrhizal (153 MOTUs) and phyllosphere (327 MOTUs) communities significantly differed from log-normal distribution. The fungal phyllosphere community in particular was clearly undersampled. This undersampling bias resulted in strong sensitivity to the exclusion of molecular singletons and other rare MOTUs that may represent technical artefacts. The analysis of abundant (core) and rare (satellite) MOTUs clearly identified two species abundance distributions in the phyllosphere data \– a log-normal model for the core group and a log-series model for the satellite group. The prominent log-series distribution of satellite phyllosphere fungi highlighted the ecological significance of an infrequent fungal component in the phyllosphere community.

}, keywords = {LTER-KNZ}, doi = {10.1111/j.1365-294X.2010.04948.x}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-294X.2010.04948.x}, author = {Unterseher, M. and Dorman, C.F. and A. Jumpponen and Moora, M. and {\"O}pik, M. and Tedersoo, L. and Schnittler, M.} } @article {KNZ001423, title = {Thinking outside the channel: modeling nitrogen cycling in networked river ecosystems}, journal = {Frontiers in Ecology and the Environment}, volume = {9}, year = {2011}, pages = {229 -238}, abstract = {

Agricultural and urban development alters nitrogen and other biogeochemical cycles in rivers worldwide. Because such biogeochemical processes cannot be measured empirically across whole river networks, simulation models are critical tools for understanding river-network biogeochemistry. However, limitations inherent in current models restrict our ability to simulate biogeochemical dynamics among diverse river networks. We illustrate these limitations using a river-network model to scale up in situ measures of nitrogen cycling in eight catchments spanning various geophysical and land-use conditions. Our model results provide evidence that catchment characteristics typically excluded from models may control river-network biogeochemistry. Based on our findings, we identify important components of a revised strategy for simulating biogeochemical dynamics in river networks, including approaches to modeling terrestrial\–aquatic linkages, hydrologic exchanges between the channel, floodplain/riparian complex, and subsurface waters, and interactions between coupled biogeochemical cycles.

}, keywords = {LTER-KNZ}, doi = {10.1890/080211}, url = {https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/080211}, author = {Helton, A.M. and Poole, G.C. and Meyer, J.L. and Wollheim, W.M. and Peterson, B.J. and Mulholland, P.J. and Bernhardt, E.S. and Stanford, J.A. and Arango, C.P. and L.R. Ashkenas and Cooper, L.W. and W. K. Dodds and Gregory, S.V. and O{\textquoteright}Hall, R. and Hamilton, S.K. and Johnson, S.L. and W.H. McDowell and Potter, J.D. and Tank, J.L. and Thomas, S.M. and Valett, H.M. and Webster, J.R. and Lydia H. Zeglin} } @article {KNZ001303, title = {Climate change and cattle nutritional stress}, journal = {Global Change Biology}, volume = {16}, year = {2010}, pages = {2901 -2911}, abstract = {

Owing to the complex interactions among climate, plants, cattle grazing, and land management practices, the impacts of climate change on cattle have been hard to predict. Predicting future grassland ecosystem functioning relies on understanding how changes in climate alter the quantity of forage produced, but also forage quality. Plant protein, which is a function of plant nitrogen concentrations, and digestible energy limit the performance of herbivores when in short supply; moreover, deficiencies can be expensive to mitigate. To better understand how changes in temperature and precipitation would affect forage protein and energy availability, we analyzed over 21 000 measurements of cattle fecal chemistry acquired over 14 years in the continental US. Our analysis of patterns in forage quality among ecologically defined regions revealed that increasing temperature and declining precipitation decreased dietary crude protein and digestible organic matter for regions with continental climates. Within regions, quality also declined with increased temperature; however, the effects of precipitation were mixed. Any future increases in precipitation would be unlikely to compensate for the declines in forage quality that accompany projected temperature increases. As a result, cattle are likely to experience greater nutritional stress in the future. If these geographic patterns hold as a proxy for future climates, agriculture will require increased supplemental feeds or the consequence will be a decrease in livestock growth.

}, keywords = {LTER-KNZ}, doi = {10.1111/j.1365-2486.2009.02060.x}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2486.2009.02060.x}, author = {Craine, J.M. and Elmore, A.J. and K.C. Olson and Tolleson, D.} } @article {KNZ001276, title = {Climate controls on grass culm production over a quarter century in a tallgrass prairie}, journal = {Ecology}, volume = {91}, year = {2010}, pages = {2132 -2140}, abstract = {

The flowering of grasses is a process critical to plant population dynamics and genetics, herbivore performance, and human health. To better understand the climate factors governing grass flowering, we analyzed the patterns of culm production over 25 years for three perennial tallgrass prairie species at Konza Prairie in Kansas, USA. The three species (Andropogon gerardii, Sorghastrum nutans, and Schizachyrium scoparium) all utilize the C4 photosynthetic pathway and were measured annually at the same locations for the past 25 years in an annually burned watershed. Culm production of all three species increased with higher growing-season soil moisture and precipitation but differed in their responses to water availability at different times during the growing season. Relative to Andropogon, Sorghastrum responded more to precipitation early in the growing season, and Schizachyrium responded more to precipitation late in the growing season. Flowering by each species also revealed a threshold relationship with late-season soil moisture at ~1 m depth, which likely is a proxy for season-long water balance. Although flowering can be influenced by conditions antecedent to the current growing season, neither soil moisture nor precipitation during the previous year influenced flowering over the 25-year period. Flowering culm production averaged 9\% and 7\% of total graminoid aboveground net primary production (ANPP) in the uplands and lowlands, respectively. Interannual variation in ANPP correlated only with Sorghastrum flowering, suggesting a predominant role of the species in ANPP responses to climate.

}, keywords = {LTER-KNZ}, doi = {10.1890/09-1242.1}, url = {https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/09-1242.1}, author = {Craine, J.M. and Towne, E.G. and Jesse B. Nippert} } @article {KNZ001300, title = {Fire and grazing in a mesic tallgrass prairie: impacts on plant species and functional traits}, journal = {Ecology}, volume = {91}, year = {2010}, pages = {1651 -1659}, abstract = {

Fire is a globally distributed disturbance that impacts terrestrial ecosystems and has been proposed to be a global \“herbivore.\” Fire, like herbivory, is a top-down driver that converts organic materials into inorganic products, alters community structure, and acts as an evolutionary agent. Though grazing and fire may have some comparable effects in grasslands, they do not have similar impacts on species composition and community structure. However, the concept of fire as a global herbivore implies that fire and herbivory may have similar effects on plant functional traits. Using 22 years of data from a mesic, native tallgrass prairie with a long evolutionary history of fire and grazing, we tested if trait composition between grazed and burned grassland communities would converge, and if the degree of convergence depended on fire frequency. Additionally, we tested if eliminating fire from frequently burned grasslands would result in a state similar to unburned grasslands, and if adding fire into a previously unburned grassland would cause composition to become more similar to that of frequently burned grasslands. We found that grazing and burning once every four years showed the most convergence in traits, suggesting that these communities operate under similar deterministic assembly rules and that fire and herbivory are similar disturbances to grasslands at the trait-group level of organization. Three years after reversal of the fire treatment we found that fire reversal had different effects depending on treatment. The formerly unburned community that was then burned annually became more similar to the annually burned community in trait composition suggesting that function may be rapidly restored if fire is reintroduced. Conversely, after fire was removed from the annually burned community trait composition developed along a unique trajectory indicating hysteresis, or a time lag for structure and function to return following a change in this disturbance regime. We conclude that functional traits and species-based metrics should be considered when determining and evaluating goals for fire management in mesic grassland ecosystems.

}, keywords = {LTER-KNZ}, doi = {10.1890/09-0431.1}, url = {https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/09-0431.1}, author = {Spasojevic, M.J. and Aicher, R.J. and Koch, G.R. and Marquardt, E.S. and Mirotchnick, N. and Troxler, T.G. and Scott. L. Collins} } @article {KNZ001345, title = {High leaf tissue density grassland species consistently more abundant across topographic and disturbance contrasts in a North American tallgrass prairie}, journal = {Plant and Soil}, volume = {337}, year = {2010}, pages = {193 -203}, abstract = {

Understanding the coupling between plant functional traits and abundance provides insight into the often hidden forces that structure plant communities. To better understand the coupling between leaf traits and abundance of grassland species in a mesic North American grassland, we measured specific leaf area (SLA) and its two components, tissue density and thickness for 125 grassland species. Plants with high tissue density were more abundant over a 17-year period across a range of environments: uplands, grazed and ungrazed watersheds, and frequently and infrequently burned watersheds. The consistent relationships between leaf tissue density and abundance across ecological contrasts imply that belowground resource availability constrains community composition independent of grazing and burning regimes. Leaf tissue density did not explain species abundance in lowlands, where belowground resources are the highest. Neither did it explain the differential abundance of species between grazing or fire frequency contrasts, suggesting that changes in burning or grazing select for species based on other traits. Relative to leaf tissue density, SLA was a poor predictor of abundance, reinforcing a long-observed\—but often ignored\—call that measurements of SLA need to be coupled with thickness measurements in order to effectively predict the performance of species. More generally, future research needs to investigate which belowground resources control community composition in the grassland and whether the importance of water or nutrients change with burning and grazing.

}, keywords = {LTER-KNZ, burning, Functional traits, Grasslands, Grazing, Konza Prairie, topography}, doi = {10.1007/s11104-010-0515-y}, url = {https://link.springer.com/article/10.1007\%2Fs11104-010-0515-y}, author = {Craine, J.M. and Towne, E.G.} } @article {KNZ001347, title = {Inter-regional comparison of land-use effects on stream metabolism}, journal = {Freshwater Biology}, volume = {55}, year = {2010}, pages = {1874 -1890}, abstract = {1. Rates of whole-system metabolism (production and respiration) are fundamental indicators of ecosystem structure and function. Although first-order, proximal controls are well understood, assessments of the interactions between proximal controls and distal controls, such as land use and geographic region, are lacking. Thus, the influence of land use on stream metabolism across geographic regions is unknown. Further, there is limited understanding of how land use may alter variability in ecosystem metabolism across regions. 2. Stream metabolism was measured in nine streams in each of eight regions (n = 72) across the United States and Puerto Rico. In each region, three streams were selected from a range of three land uses: agriculturally influenced, urban-influenced, and reference streams. Stream metabolism was estimated from diel changes in dissolved oxygen concentrations in each stream reach with correction for reaeration and groundwater input. 3. Gross primary production (GPP) was highest in regions with little riparian vegetation (sagebrush steppe in Wyoming, desert shrub in Arizona/New Mexico) and lowest in forested regions (North Carolina, Oregon). In contrast, ecosystem respiration (ER) varied both within and among regions. Reference streams had significantly lower rates of GPP than urban or agriculturally influenced streams. 4. GPP was positively correlated with photosynthetically active radiation and autotrophic biomass. Multiple regression models compared using Akaike{\textquoteright}s information criterion (AIC) indicated GPP increased with water column ammonium and the fraction of the catchment in urban and reference land-use categories. Multiple regression models also identified velocity, temperature, nitrate, ammonium, dissolved organic carbon, GPP, coarse benthic organic matter, fine benthic organic matter and the fraction of all land-use categories in the catchment as regulators of ER. 5. Structural equation modelling indicated significant distal as well as proximal control pathways including a direct effect of land-use on GPP as well as SRP, DIN, and PAR effects on GPP; GPP effects on autotrophic biomass, organic matter, and ER; and organic matter effects on ER. 6. Overall, consideration of the data separated by land-use categories showed reduced inter-regional variability in rates of metabolism, indicating that the influence of agricultural and urban land use can obscure regional differences in stream metabolism.}, keywords = {LTER-KNZ}, doi = {10.1111/j.1365-2427.2010.02422.x}, author = {Bernot, M.J. and Sobota, D.J. and Hall, R.O. and Mulholland, P.J. and W. K. Dodds and Webster, J.R. and Tank, J.L. and L.R. Ashkenas and Cooper, L.W. and Dahm, C.N. and Gregory, S.V. and Grimm, N.B. and Hamilton, S.K. and Johnson, S.L. and W.H. McDowell and Meyer, J.L. and Peterson, B. and Poole, G.C. and Valett, H.M. and Arango, C.P. and Beaulieu, J.J. and Burgin, A.J. and Crenshaw, C. and Helton, A.M. and Johnson, L. and Merriam, J. and Niederlehner, B.R. and O{\textquoteright}Brien, J.M. and Potter, J.D. and Sheibley, R.W. and Thomas, S.M. and Wilson, K.} } @article {KNZ001319, title = {Microbial protein in soil: influence of extraction method and C amendment on extraction and recovery}, journal = {Microbial Ecology}, volume = {59}, year = {2010}, pages = {390 -399}, abstract = {The capacity to study the content and resolve the dynamics of the proteome of diverse microbial communities would help to revolutionize the way microbiologists study the function and activity of microorganisms in soil. To better understand the limitations of a proteomic approach to studying soil microbial communities, we characterized extractable soil microbial proteins using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Two methods were utilized to extract proteins from microorganisms residing in a Quitman and Benfield soil: (1) direct extraction of bulk protein from soil and (2) separation of the microorganisms from soil using density gradient centrifugation and subsequent extraction (DGC{\textendash}EXT) of microbial protein. In addition, glucose and toluene amendments to soil were used to stimulate the growth of a subset of the microbial community. A bacterial culture and bovine serum albumin (BSA) were added to the soil to qualitatively assess their recovery following extraction. Direct extraction and resolution of microbial proteins using SDS-PAGE generally resulted in smeared and unresolved banding patterns on gels. DGC{\textendash}EXT of microbial protein from soil followed by separation using SDS-PAGE, however, did resolve six to 10 bands in the Benfield but not the Quitman soil. DGC{\textendash}EXT of microbial protein, but not direct extraction following the addition of glucose and toluene, markedly increased the number of bands (~40) on the gels in both Benfield and Quitman soils. Low recoveries of added culture and BSA proteins using the direct extraction method suggest that proteins either bind to soil organic matter and mineral particles or that partial degradation takes place during extraction. Interestingly, DGC may have been preferentially selected for actively growing cells, as gauged by the 10{\textendash}100{\texttimes} lower cy19:0/18:1ω7 ratio of the fatty acid methyl esters in the isolated community compared to that for the whole soil. DGC can be used to isolate soil communities and provide microbial protein that can be characterized using PAGE.}, keywords = {LTER-KNZ}, doi = {10.1007/s00248-009-9593-x}, author = {Taylor, E.B. and Williams, M.A.} } @mastersthesis {KNZ001342, title = {Morphological and physiological traits as indicators of drought tolerance in tallgrass prairie plants}, volume = {MS Thesis}, year = {2010}, school = {Kansas State University}, type = {M.S. Thesis}, address = {Manhattan, KS}, abstract = {

The Konza Prairie in northern Kansas, USA contains over 550 vascular plant species; of which, few have been closely studied. These species are adapted to environmental stress as imposed by variable temperature, precipitation, fire, and grazing. Understanding which plant traits relate to drought responses will allow us to both predict drought tolerance and potential future shifts in plant community composition from changes in local climate. Morphological and physiological measurements were taken on 121 species of herbaceous tallgrass prairie plants grown from seed in a growth chamber. Gas exchange measurements including maximum photosynthetic rate, stomatal conductance to water vapor, and intercellular CO[subscript]2 concentration were measured. All plants were exposed to a drought treatment and were monitored daily until stomatal conductance was zero. At this point, critical leaf water potential (Ψ[subscript]crit), an indicator of physiological drought tolerance was assessed. Other measurements include root length, diameter, volume, and mass, leaf area, leaf tissue density, root tissue density, and root to shoot ratio. Traits were compared using pair-wise bivariate analysis and principal component analysis (PCA). A dichotomy was found between dry-adapted plants with thin, dense leaves and roots, high leaf angle, and highly negative Ψ[subscript]crit and hydrophiles which have the opposite profile. A second axis offers more separation based on high photosynthetic rate, high conductance rate, and leaf angle, but fails to provide a distinction between C[subscript]3 and C[subscript]4 species. When tested independently, grasses and forbs both showed drought tolerance strategies similar to the primary analysis. Matching up these axes with long term abundance data suggests that species with drought tolerance traits have increased abundance on Konza, especially in upland habitats. However, traits that relate to drought tolerance mirror relationships with nutrient stress, confounding separation of low water versus low nutrient strategies. My results not only illustrate the utility of morphological and physiological plant traits in classifying drought responses across a range of species, but as functional traits in predicting both drought tolerance in individual species and relative abundance across environmental gradients of water availability.

}, keywords = {LTER-KNZ, Abundance; Konza, Drought Tolerance, Plant traits, tallgrass prairie}, url = {http://krex.k-state.edu/dspace/handle/2097/4628}, author = {Tucker, S.} } @article {KNZ001266, title = {Relatedness of Macrophomina phaseolina isolates from tallgrass prairie, maize, soybean, and sorghum}, journal = {Molecular Ecology}, volume = {19}, year = {2010}, pages = {79 -91}, abstract = {

Agricultural and wild ecosystems may interact through shared pathogens such as Macrophomina phaseolina, a generalist clonal fungus with more than 284 plant hosts that is likely to become more important under climate change scenarios of increased heat and drought stress. To evaluate the degree of subdivision in populations of M. phaseolina in Kansas agriculture and wildlands, we compared 143 isolates from maize fields adjacent to tallgrass prairie, nearby sorghum fields, widely dispersed soybean fields and isolates from eight plant species in tallgrass prairie. Isolate growth phenotypes were evaluated on a medium containing chlorate. Genetic characteristics were analysed based on amplified fragment length polymorphisms and the sequence of the rDNA-internal transcribed spacer (ITS) region. The average genetic similarity was 58\% among isolates in the tallgrass prairie, 71\% in the maize fields, 75\% in the sorghum fields and 80\% in the dispersed soybean fields. The isolates were divided into four clusters: one containing most of the isolates from maize and soybean, two others containing isolates from wild plants and sorghum, and a fourth containing a single isolate recovered from Solidago canadensis in the tallgrass prairie. Most of the sorghum isolates had the dense phenotype on media containing chlorate, while those from other hosts had either feathery or restricted phenotypes. These results suggest that the tallgrass prairie supports a more diverse population of M. phaseolina per area than do any of the crop species. Subpopulations show incomplete specialization by host. These results also suggest that inoculum produced in agriculture may influence tallgrass prairie communities, and conversely that different pathogen subpopulations in tallgrass prairie can interact there to generate \‘hybrids\’ with novel genetic profiles and pathogenic capabilities.

}, keywords = {LTER-KNZ}, doi = {10.1111/j.1365-294X.2009.04433.x}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-294X.2009.04433.x}, author = {Saleh, A.A. and Ahmed, H.U. and Todd, T.C. and Travers, S.E. and Zeller, K.A. and Leslie, J.F. and Garrett, K.A.} } @article {KNZ001293, title = {Variation in gene expression of Andropogon gerardii in response to altered environmental conditions associated with climate change}, journal = {Journal of Ecology}, volume = {98}, year = {2010}, pages = {374 -383}, abstract = {

1.\ If we are to understand the mechanisms underlying species responses to climate change in natural systems, studies are needed that focus on responses of non-model species under field conditions. We measured transcriptional profiles of individuals of Andropogon gerardii, a C4 grass native to North American grasslands, in a field experiment in which both temperature and precipitation were manipulated to simulate key aspects of forecasted climate change. 2.\ By using microarrays developed for a closely related model species, Zea mays, we were able to compare the relative influence of warming versus altered soil moisture availability on expression levels of over 7000 genes, identify responsive functional groups of genes and correlate changes in gene transcription with physiological responses. 3.\ We observed more statistically significant shifts in transcription levels of genes in response to thermal stress than in response to water stress. We also identified candidate genes that demonstrated transcription levels closely associated with physiological variables, in particular chlorophyll fluorescence. 4.Synthesis. These results suggest that an ecologically important species responds differently to different environmental aspects of forecast climate change. These translational changes have the potential to influence phenotypic characters and ultimately adaptive responses.

}, keywords = {LTER-KNZ}, doi = {10.1111/j.1365-2745.2009.01618.x}, url = {https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2745.2009.01618.x}, author = {Travers, S.E. and Tang, Z. and Caragea, D. and Garrett, K.A. and Hulbert, S.H. and Leach, J.E. and Bai, J. and Saleh, A. and Alan K. Knapp and Fay, P.A. and Jesse B. Nippert and Schnable, P.S. and M.D. Smith} } @article {KNZ001240, title = {Consequences of climate variability for the performance of bison in tallgrass prairie}, journal = {Global Change Biology}, volume = {15}, year = {2009}, pages = {772 -779}, abstract = {

Climate variability is a major structuring factor in grassland ecosystems, yet there is great uncertainty in how changes in precipitation affect grazing herbivores. We determined how interannual variation in the timing and magnitude of precipitation affected the weight gain of free-roaming bison in their first and second year. Bison weights were analyzed for 14 years for Konza Prairie, Kansas, and 12 years for Tallgrass Prairie Preserve, Oklahoma. Greater late-summer precipitation increased bison weight gain. For every 100 mm precipitation, weight gain increased 6.4\–15.3 kg depending on age classes and site. In contrast, greater midsummer precipitation decreased weight gain. For every additional 100 mm precipitation, weight decreased 9.7\–17.3 kg depending on age class and site. The decreased weight gain of bison with greater midsummer precipitation was associated with increased grass stem production during the period for each of three dominant grasses at Konza Prairie. Although greater stem production increases the quantity of aboveground biomass, it should decrease the overall nutritional quality of biomass to grazers, which would reduce weight gain. With offsetting effects of mid- and late-summer precipitation on weight gain, these results show that predicting the effects of climate change on grazers must incorporate both the timing and magnitude of changes in precipitation and their effects on both the quantity and quality of biomass.

}, keywords = {LTER-KNZ}, doi = {10.1111/j.1365-2486.2008.01769.x}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2486.2008.01769.x}, author = {Craine, J.M. and Towne, E.G. and Anthony Joern and Hamilton, R.G.} } @article {KNZ001324, title = {The influence of land use on stream biofilm nutrient limitation across eight North American ecoregions}, journal = {Canadian Journal of Fisheries and Aquatic Sciences}, volume = {66}, year = {2009}, pages = {1081 -1094}, abstract = {

Nutrient diffusing substrata were used to determine the influence of inorganic nitrogen (N) and phosphorus (P) availability on community respiration (CR), gross primary production (GPP), and chlorophyll a (chl a) on inorganic and organic substrata. We incubated substrata in nine streams each in a total of eight ecoregions (n = 72 streams) located in a range of native vegetation, agriculture, and urban land-use types. On organic substrata, CR was nutrient-limited in 94\% of reference streams but showed significant nutrient limitation in only 60\% and 65\% of agricultural and urban streams, respectively. The relative magnitude of nutrient limitation for CR on organic substrata decreased with increasing percent modified land use in the basin (agriculture + urban). On inorganic and organic substrata, GPP and chl a were rarely nutrient-limited across all ecoregions and land-use types, although the magnitude of nutrient limitation increased with increasing light availability. The effect of human land use on nutrient limitation of biofilm CR, GPP, and chl a was influenced by ecoregion, yet heterotrophic biofilms were consistently most sensitive to nutrient enrichment across ecoregions. Both heterotrophic and autotrophic biofilm constituents should be considered to fully understand stream ecosystem responses to nutrient enrichment.

}, keywords = {LTER-KNZ}, doi = {10.1139/F09-065}, url = {http://www.nrcresearchpress.com/doi/10.1139/F09-065}, author = {Johnson, L.T. and Tank, J.L. and W. K. Dodds} } @article {KNZ001255, title = {Limiting temperatures for urediniospore germination are low in a systemic rust fungus of tallgrass prairie}, journal = {Mycologia}, volume = {101}, year = {2009}, pages = {390 -394}, abstract = {

Potential responses of plant disease phenology to climate change have been addressed primarily in agricultural systems. As a first step toward understanding the phenology of Uropyxis petalostemonis, a rust fungus commonly infecting the legume Dalea candida in USA tallgrass prairie, we evaluated the effects of temperature on urediniospore germination. While urediniospore germination for many rust fungi has been reported to decline only when temperatures are well above 25 C, in vitro germination of U petalostemonis dropped sharply at this temperature. Responses observed on water agar, potato dextrose agar and lima bean agar were similar, although lima bean agar supported a higher percentage germination overall. The low limiting temperatures suggest that most epidemically important new infections by U petalostemonis occur in spring. High summer temperatures in tallgrass prairie might push infection by this rust fungus species to earlier in the year and select for stronger systemic growth characteristics.

}, keywords = {LTER-KNZ, Basidiomycetes, Dalea candida, Fabaceae, phenology, Uredinales, Uropyxis petalostemonis}, doi = {10.3852/08-102}, url = {https://www.tandfonline.com/doi/abs/10.3852/08-102?journalCode=umyc20}, author = {Worapong, J. and Dendy, S.P. and Tang, Z. and Awl, D.J. and Garrett, K.A.} } @article {KNZ001251, title = {Nitrate removal in stream ecosystems measured by 15N addition experiments: Denitrification}, journal = {Limnology and Oceanography}, volume = {54}, year = {2009}, pages = {666 -680}, abstract = {

We measured denitrification rates using a field 15NO3\− tracer-addition approach in a large, cross-site study of nitrate uptake in reference, agricultural, and suburban-urban streams. We measured denitrification rates in 49 of 72 streams studied. Uptake length due to denitrification (SWdenn) ranged from 89 m to 184 km (median of 9050 m) and there were no significant differences among regions or land-use categories, likely because of the wide range of conditions within each region and land use. N2 production rates far exceeded N2O production rates in all streams. The fraction of total NO3\− removal from water due to denitrification ranged from 0.5\% to 100\% among streams (median of 16\%), and was related to NH4+ concentration and ecosystem respiration rate (ER). Multivariate approaches showed that the most important factors controlling SWden were specific discharge (discharge / width) and NO3\− concentration (positive effects), and ER and transient storage zones (negative effects). The relationship between areal denitrification rate (Uden) and NO3\− concentration indicated a partial saturation effect. A power function with an exponent of 0.5 described this relationship better than a Michaelis-Menten equation. Although Uden increased with increasing NO3\− concentration, the efficiency of NO3\− removal from water via denitrification declined, resulting in a smaller proportion of streamwater NO3\− load removed over a given length of stream. Regional differences in stream denitrification rates were small relative to the proximate factors of NO3\− concentration and ecosystem respiration rate, and land use was an important but indirect control on denitrification in streams, primarily via its effect on NO3\− concentration.

}, keywords = {LTER-KNZ}, doi = {10.4319/lo.2009.54.3.0666}, url = {https://aslopubs.onlinelibrary.wiley.com/doi/abs/10.4319/lo.2009.54.3.0666}, author = {Mulholland, P.J. and Hall, R.O. and Sobota, D.J. and W. K. Dodds and Findlay, S.E.G. and Grimm, N.B. and Hamilton, S.K. and W.H. McDowell and O{\textquoteright}Brien, J.M. and Tank, J.L. and L.R. Ashkenas and Cooper, L.W. and Dahm, C.N. and Gregory, S.V. and Johnson, S.L. and Meyer, J.L. and Peterson, B.J. and Poole, G.C. and Valett, H.M. and Webster, J.R. and Arango, C.P. and Beaulieu, J.J. and Bernot, M.J. and Burgin, A.J. and Crenshaw, C.L. and Helton, A.M. and Johnson, L.T. and Niederlehner, B.R. and Potter, J.D. and Sheibley, R.W. and Thomas, S.M.} } @article {KNZ001250, title = {Nitrate removal in stream ecosystems measured by 15N addition experiments: Total uptake}, journal = {Limnology and Oceanography}, volume = {54}, year = {2009}, pages = {653 -665}, abstract = {

We measured uptake length of 15NO3\− in 72 streams in eight regions across the United States and Puerto Rico to develop quantitative predictive models on controls of NO3\− uptake length. As part of the Lotic Intersite Nitrogen eXperiment II project, we chose nine streams in each region corresponding to natural (reference), suburban-urban, and agricultural land uses. Study streams spanned a range of human land use to maximize variation in NO3\− concentration, geomorphology, and metabolism. We tested a causal model predicting controls on NO3\− uptake length using structural equation modeling. The model included concomitant measurements of ecosystem metabolism, hydraulic parameters, and nitrogen concentration. We compared this structural equation model to multiple regression models which included additional biotic, catchment, and riparian variables. The structural equation model explained 79\% of the variation in log uptake length (SWtot). Uptake length increased with specific discharge (Q/w) and increasing NO3\− concentrations, showing a loss in removal efficiency in streams with high NO3\− concentration. Uptake lengths shortened with increasing gross primary production, suggesting autotrophic assimilation dominated NO3\− removal. The fraction of catchment area as agriculture and suburban-urban land use weakly predicted NO3\− uptake in bivariate regression, and did improve prediction in a set of multiple regression models. Adding land use to the structural equation model showed that land use indirectly affected NO3\− uptake lengths via directly increasing both gross primary production and NO3\− concentration. Gross primary production shortened SWtot, while increasing NO3\− lengthened SWtot resulting in no net effect of land use on NO3\− removal.

}, keywords = {LTER-KNZ}, doi = {10.4319/lo.2009.54.3.0653}, url = {https://aslopubs.onlinelibrary.wiley.com/doi/abs/10.4319/lo.2009.54.3.0653}, author = {Hall, R.O. Jr. and Tank, J.L. and Sobota, D.J. and Mulholland, P.J. and O{\textquoteright}Brien, J.M. and W. K. Dodds and Webster, J.R. and Valett, H.M. and Poole, G.C. and Peterson, B.J. and Meyer, J.L. and W.H. McDowell and Johnson, S.L. and Hamilton, S.K. and Grimm, N.B. and Gregory, S.V. and Dahm, C.N. and Cooper, L.W. and L.R. Ashkenas and Thomas, S.M. and Sheibley, R.W. and Potter, J.D. and Niederlehner, B.R. and Johnson, L.T. and Helton, A.M. and Crenshaw, C.M. and Burgin, A.J. and Bernot, M.J. and Beaulieu, J.J. and Arango, C.P.} } @article {KNZ001230, title = {Increasing shallow groundwater CO2 and limestone weathering, Konza Prairie, USA}, journal = {Geochimica et Cosmochimica Acta}, volume = {72}, year = {2008}, pages = {5581 -5599}, abstract = {

In a mid-continental North American grassland, solute concentrations in shallow, limestone-hosted groundwater and adjacent surface water cycle annually and have increased steadily over the 15-year study period, 1991\–2005, inclusive. Modeled groundwater CO2, verified by measurements of recent samples, increased from 10\−2.05 atm to 10\−1.94 atm, about a 20\% increase, from 1991 to 2005. The measured groundwater alkalinity and alkaline-earth element concentrations also increased over that time period. We propose that carbonate minerals dissolve in response to lowered pH that occurs during an annual carbonate-mineral saturation cycle. The cycle starts with low saturation during late summer and autumn when dissolved CO2 is high. As dissolved CO2 decreases in the spring and early summer, carbonates become oversaturated, but oversaturation does not exceed the threshold for precipitation. We propose that groundwater is a CO2 sink through weathering of limestone: soil-generated CO2 is transformed to alkalinity through dissolution of calcite or dolomite. The annual cycle and long-term increase in shallow groundwater CO2 is similar to, but greater than, atmospheric CO2.

}, keywords = {LTER-KNZ}, doi = {10.1016/j.gca.2008.09.004}, url = {https://www.sciencedirect.com/science/article/pii/S001670370800536X?via\%3Dihub}, author = {G. L. Macpherson and Roberts, J.A. and John M. Blair and Townsend, M.A. and Fowle, D.A. and Beisner, K.R.} } @article {KNZ001225, title = {Long-term response patterns of tallgrass prairie to frequent summer burning}, journal = {Rangeland Ecology and Management}, volume = {61}, year = {2008}, pages = {509 -520}, abstract = {

Knowledge of how tallgrass prairie vegetation responds to fire in the late growing season is relatively sparse and is based upon studies that are either spatially or temporally limited. To gain a more robust perspective of vegetation response to summer burning and to determine if repeated summer fire can drive vegetational changes in native tallgrass prairie, we evaluated species cover and richness over a 14-yr period on different topographic positions from ungrazed watersheds that were burned biennially in the growing season. We found that annual forbs were the primary beneficiaries of summer burning, but their fluctuations varied inconsistently among years. Concomitantly, species richness and diversity increased significantly with summer burning but remained stable through time with annual spring burning. After 14 yr, species richness was 28\% higher in prairie that was burned in the summer than in prairie burned in the spring. Canopy cover of big bluestem (Andropogon gerardii Vitman) and Indiangrass (Sorghastrum nutans [L.] Nash) increased significantly over time with both summer and spring burning, whereas heath aster (Symphyotrichum ericoides [L.] Nesom), aromatic aster (Symphyotrichum oblongifolium [Nutt.] Nesom), and sedges (Carex spp.) increased in response to only summer burning. Kentucky bluegrass (Poa pratensis L.) cover declined in both spring-burned and summer-burned watersheds. Repeated burning in either spring or summer did not reduce the cover or frequency of any woody species. Most perennial species were neutral in their reaction to summer fire, but a few species responded with large and inconsistent temporal fluctuations that overwhelmed any clear patterns of change. Although summer burning did not preferentially encourage spring-flowering forbs or suppress dominance of the warm-season grasses, it is a potentially useful tool to increase community heterogeneity in ungrazed prairie.

}, keywords = {LTER-KNZ, burn season, fire ecology, grassland vegetation, growing-season fire}, doi = {10.2111/08-043.1}, url = {https://www.sciencedirect.com/science/article/pii/S1550742408500674?via\%3Dihub}, author = {Towne, G.E. and Kemp, K.E.} } @article {KNZ001159, title = {Plasma cholinesterases for monitoring pesticide exposure in Nearctic-Neotropical migratory shorebirds}, journal = {Ornitholog{\'\i}a Neotropical}, volume = {19 (Suppl)}, year = {2008}, pages = {641 -651}, abstract = {Organophosphorus (OP) and carbamate (CB) pesticides are commonly used agrochemicals throughout the Western Hemisphere. These pesticides have caused mortalities in migratory birds and adverse physiological effects in trials with captive birds. Migratory shorebirds use a variety, of habitats during the austral summer in temperate South America and during migration through the Great Plains of the United States. Habitats where risk of exposure is high include rice fields and turf grass farms where agrochemicals are used. Cholinesterase (ChE) is a specific biomarker for monitoring OP and CB exposure and can be measured using standard laboratory procedures. Plasma ChE activity is useful as a non-lethal means of monitoring avian exposure to OP and CB pesticides. Many variables can affect enzyme activity and reactivation assays are not always possible, thus reference ChE values are a necessary component of monitoring exposure. During northbound migration in 2006, we sampled four upland and five wetland shore-bird species at four pesticide-free sites in North America, characterizing and measuring plasma ChEs in all shorebird species. Small-bodied species had higher levels of ChE activity in plasma than large-bodied species. Acetylcholinesterase (AChE), the enzyme whose inhibition leads to poisoning symptoms, showed less inter-specific variation than butyrylcholinesterase (BChE). Plasma ChE activities varied with date of capture in three of five species. Sex differences were significant in one of two species tested. Our baseline ChE values for migratory shorebirds provide a framework for future ecotoxicological studies of Nearctic-Neotropical migrant shorebirds.}, keywords = {LTER-KNZ}, url = {https://www.researchgate.net/publication/254414753_Plasma_cholinesterases_for_monitoring_pesticide_exposure_in_Nearctic-Neotropical_migratory_shorebirds}, author = {Strum, K.M. and Alfaro, M. and Haase, B. and Hooper, M.J. and Johnson, K.A. and Lanctot, R.B. and Lesterhuis, A.J. and L{\'o}pez, L. and Matz, A.C. and Morales, C. and Paulson, B. and Sandercock, B.K. and Torres-Dowdall, J. and Zaccagnini, M.E.} } @article {KNZ001180, title = {Species responses to nitrogen fertilization in herbaceous plant communities, and associated species traits}, journal = {Ecology}, volume = {89}, year = {2008}, pages = {1175 -}, abstract = {

This synthetic data set contains plant species relative abundance measures from 35 nitrogen (N) fertilization experiments conducted at 10 sites across North America. The data set encompasses the fertilization responses of 575 taxa from 1159 experimental plots. The methodology varied among experiments, in particular with regard to the type and amount of N added, plot size, species composition measure (biomass harvest, pin count, or percent cover), additional experimental manipulations, and experimental duration. At each site, each species has been classified according to a number of easily identified categorical functional traits, including life history, life form, the number of cotyledons, height relative to the canopy, potential for clonal growth, and nativity to the United States. Additional data are available for many sites, indicated by references to publications and web sites. Analyses of these data have shown that N enrichment significantly alters community composition in ways that are predictable on the basis of plant functional traits as well as environmental context. This data set could be used to answer a variety of questions about how plant community composition and structure respond to environmental changes.

}, keywords = {LTER-KNZ}, doi = {10.1890/07-1104.1}, url = {https://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/07-1104.1}, author = {Cleland, E.E. and Clark, C.M. and Scott. L. Collins and Fargione, J.E. and Gough, L. and Gross, K.L. and Pennings, S.C. and W.D. Bowman and Robertson, G.P. and Simpson, J. and Tilman, D. and K.N. Suding} } @article {KNZ001164, title = {Stream denitrification across biomes and its response to anthropogenic nitrate loading}, journal = {Nature}, volume = {452}, year = {2008}, pages = {202 -207}, abstract = {

Anthropogenic addition of bioavailable nitrogen to the biosphere is increasing1, 2 and terrestrial ecosystems are becoming increasingly nitrogen-saturated3, causing more bioavailable nitrogen to enter groundwater and surface waters4, 5, 6. Large-scale nitrogen budgets show that an average of about 20\–25 per cent of the nitrogen added to the biosphere is exported from rivers to the ocean or inland basins7, 8, indicating that substantial sinks for nitrogen must exist in the landscape9. Streams and rivers may themselves be important sinks for bioavailable nitrogen owing to their hydrological connections with terrestrial systems, high rates of biological activity, and streambed sediment environments that favour microbial denitrification6, 10, 11. Here we present data from nitrogen stable isotope tracer experiments across 72 streams and 8 regions representing several biomes. We show that total biotic uptake and denitrification of nitrate increase with stream nitrate concentration, but that the efficiency of biotic uptake and denitrification declines as concentration increases, reducing the proportion of in-stream nitrate that is removed from transport. Our data suggest that the total uptake of nitrate is related to ecosystem photosynthesis and that denitrification is related to ecosystem respiration. In addition, we use a stream network model to demonstrate that excess nitrate in streams elicits a disproportionate increase in the fraction of nitrate that is exported to receiving waters and reduces the relative role of small versus large streams as nitrate sinks.

}, keywords = {LTER-KNZ}, doi = {10.1038/nature06686}, url = {https://www.nature.com/articles/nature06686}, author = {Mulholland, P.J. and Helton, A.M. and Poole, G.C. and Hall, R.O. Jr. and Hamilton, S.K. and Peterson, B.J. and Tank, J.L. and L.R. Ashkenas and Cooper, L.W. and Dahm, C.N. and W. K. Dodds and Findlay, S.E.G. and Gregory, S.V. and Grimm, N.B. and Johnson, S.L. and W.H. McDowell and Meyer, J.L. and Valett, H.M. and Webster, J.R. and Arango, C.P. and Beaulieu, J.J. and Bernot, M.J. and Burgin, A.J. and Crenshaw, C. and Johnson, L. and Niederlehner, B.R. and O{\textquoteright}Brien, J.M. and Potter, J.D. and Sheibley, R.W. and Sobota, D.J. and Thomas, S.M.} } @article {KNZ001083, title = {Ecological genomics: making the leap from model systems in the lab to native populations in the field. Frontiers in Ecology and the Environment}, journal = {Frontiers in Ecology and the Environment}, volume = {5}, year = {2007}, pages = {19 -24}, abstract = {Recent reviews have emphasized the need to incorporate genomics into ecological field studies to further understand how species respond to changing environmental conditions. Genomic tools, such as cDNA (complementary DNA) microarrays, allow for the simultaneous analysis of gene expression of thousands of genes from all or part of an organism{\textquoteright}s genome (the transcription profile), thereby revealing the genetic mechanisms that underlie species{\textquoteright} responses to environmental change. However, despite their potential, two major limitations have hindered the incorporation of microarrays and other genomic tools into field studies: (1) the limited availability of microarrays for ecologically relevant, non-model species and limited financial resources for developing new microarrays; and (2) concern that high sensitivity of gene expression to even subtle alterations in environmental conditions will hinder detection of relevant changes in field measures of transcription profiles. Here, we show that with cross-species hybridizations of microarrays developed for a closely related model organism, an appropriate experimental design, and sufficient replication, transcriptional profiling can successfully be incorporated into field studies. In this way, relevant changes in gene expression with changing environmental conditions can be detected.}, keywords = {LTER-KNZ}, doi = {10.1890/1540-9295(2007)5[19:EGMTLF]2.0.CO;2}, author = {Travers, S.E. and M.D. Smith and Bai, J. and Hulbert, S.H. and Leach, J.E. and Schnable, P.S. and Alan K. Knapp and Milliken, G.A. and Fay, P.A. and Saleh, A. and Garrett, K.A.} } @article {KNZ001199, title = {Experimentaldesign for two-color microarrays applied in a pre-existing split-plotexperiment}, journal = {Statistical Applications in Genetics and Molecular Biology}, volume = {6}, year = {2007}, abstract = {Microarray applications for the study of gene expression are becoming accessible for researchers in more and more systems. Applications from field or laboratory experiments are often complicated by the need to superimpose sample pairing for two-color arrays on experimental designs that may already be complex. For example, split-plot designs are commonly used in biological systems where experiments involve two types of treatments that are not readily applied at the same scale. We demonstrate how effects that are confounded with arrays can still be estimated when there is sufficient replication. To illustrate, we evaluate three methods of sample pairing superimposed on a split-plot design with two treatments, deriving the variance associated with parameter estimates for each. Design A has levels of the whole plot treatment paired on the same microarray within a level of the subplot treatment. Design B has crossed levels paired on the same microarray. Design C has levels of the treatment applied to subplots paired on the same microarray within a whole plot. Designs A and B have lower variance than design C for comparing the levels of the whole plot treatment. Designs B and C have lower variance for comparing the levels of the subplot treatment and design C has lower variance for comparing the levels of the subplot treatment within each level of the whole plot treatment. We provide SAS code for the analyses of variance discussed.}, keywords = {LTER-KNZ, Ecological genomics, experimental design, gene expression, microarray analysis, split-plot design}, doi = {10.2202/1544-6115.1245}, url = {http://www.bepress.com/sagmb/vol6/iss1/art20}, author = {Milliken, G.A. and Garrett, K.A. and Travers, S.E.} } @article {KNZ001063, title = {Climate change effects on plant disease: from genes to ecosystems}, journal = {Annual Review of Phytopathology}, volume = {44}, year = {2006}, pages = {489 -509}, abstract = {Research in the effects of climate change on plant disease continues to be limited, but some striking progress has been made. At the genomic level, advances in technologies for the high-throughput analysis of gene expression have made it possible to begin discriminating responses to different biotic and abiotic stressors and potential trade-offs in responses. At the scale of the individual plant, enough experiments have been performed to begin synthesizing the effects of climate variables on infection rates, though pathosystem-specific characteristics make synthesis challenging. Models of plant disease have now been developed to incorporate more sophisticated climate predictions. At the population level, the adaptive potential of plant and pathogen populations may prove to be one of the most important predictors of the magnitude of climate change effects. Ecosystem ecologists are now addressing the role of plant disease in ecosystem processes and the challenge of scaling up from individual infection probabilities to epidemics and broader impacts.}, keywords = {LTER-KNZ}, doi = {10.1146/annurev.phyto.44.070505.143420}, author = {Garrett, K.A. and Dendy, S.P. and Frank, E.E. and Rouse, M.N. and Travers, S.E.} } @article {KNZ001101, title = {Development of taxon-specific markers for high-throughput screening of microbial-feeding nematodes}, journal = {Molecular Ecology Notes}, volume = {6}, year = {2006}, pages = {712 -714}, abstract = {In an effort to assess the taxonomic identity of large-scale samplings of nematodes from the Konza Tallgrass Prairie, we sequenced a portion of the 18S rRNA gene and its associated internally transcribed spacer (ITS1) from 74 nematodes encompassing four taxonomic families. From these sequences, we have developed a series of molecular probes to distinguish 16 distinct microbivorous nematode taxa. Using a combination of low power microscopy and taxon-specific real-time probes, the 74 nematodes were correctly assigned to their respective taxonomic groups. This optimized method provides a high-throughput assay to determine nematode identities across larger data sets.}, keywords = {LTER-KNZ, 18S rRNA, 5' nuclease assaym, Nematoda, real-time PCR, Taqman}, doi = {10.1111/j.1471-8286.2006.01319.x}, author = {Jones, K.L. and Todd, T.C. and Herman, M.A.} } @article {KNZ001028, title = {Ecological genomics and epidemiology}, journal = {European Journal of PlantPathology}, volume = {115}, year = {2006}, pages = {35 -51}, abstract = {The huge amount of genomic data now becoming available offers both opportunities and challenges for epidemiologists. In this {\textquotedblleft}preview{\textquotedblright} of likely developments as the field of ecological genomics evolves and merges with epidemiology, we discuss how epidemiology can use new information about genetic sequences and gene expression to form predictions about epidemic features and outcomes and for understanding host resistance and pathogen evolution. DNA sequencing is now complete for some hosts and several pathogens. Microarrays make it possible to measure gene expression simultaneously for thousands of genes. These tools will contribute to plant disease epidemiology by providing information about which resistance or pathogenicity genes are present in individuals and populations, what genes other than those directly involved in resistance and virulence are important in epidemics, the role of the phenotypic status of hosts and pathogens, and the role of the status of the environmental metagenome. Conversely, models of group dynamics supplied by population biology and ecology may be used to interpret gene expression within individual organisms and in populations of organisms. Genomic tools have great potential for improving understanding of resistance gene evolution and the durability of resistance. For example, DNA sequence analysis can be used to evaluate whether an arms race model of co-evolution is supported. Finally, new genomic tools will make it possible to consider the landscape ecology of epidemics in terms of host resistance both as determined by genotype and as expressed in host phenotypes in response to the biotic and abiotic environment. Host phenotype mixtures can be modeled and evaluated, with epidemiological predictions based on phenotypic characteristics such as physiological age and status in terms of induced systemic resistance or systemic acquired resistance.}, keywords = {LTER-KNZ}, doi = {10.1007/s10658-005-4050-2}, author = {Garrett, K.A. and Hulbert, S.H. and Leach, J.E. and Travers, S.E.} } @article {KNZ001109, title = {Effects of floods on fish assemblages in an intermittent prairie stream}, journal = {Freshwater Biology}, volume = {51}, year = {2006}, pages = {2072 -2086}, abstract = {1. Floods are major disturbances to stream ecosystems that can kill or displace organisms and modify habitats. Many studies have reported changes in fish assemblages after a single flood, but few studies have evaluated the importance of timing and intensity of floods on long-term fish assemblage dynamics. 2. We used a 10-year dataset to evaluate the effects of floods on fishes in Kings Creek, an intermittent prairie stream in north-eastern, Kansas, U.S.A. Samples were collected seasonally at two perennial headwater sites (1995{\textendash}2005) and one perennial downstream flowing site (1997{\textendash}2005) allowing us to evaluate the effects of floods at different locations within a watershed. In addition, four surveys during 2003 and 2004 sampled 3{\textendash}5 km of stream between the long-term study sites to evaluate the use of intermittent reaches of this stream. 3. Because of higher discharge and bed scouring at the downstream site, we predicted that the fish assemblage would have lowered species richness and abundance following floods. In contrast, we expected increased species richness and abundance at headwater sites because floods increase stream connectivity and create the potential for colonisation from downstream reaches. 4. Akaike Information Criteria (AIC) was used to select among candidate regression models that predicted species richness and abundance based on Julian date, time since floods, season and physical habitat at each site. At the downstream site, AIC weightings suggested Julian date was the best predictor of fish assemblage structure, but no model explained >16\% of the variation in species richness or community structure. Variation explained by Julian date was primarily attributed to a long-term pattern of declining abundance of common species. At the headwater sites, there was not a single candidate model selected to predict total species abundance and assemblage structure. AIC weightings suggested variation in assemblage structure was associated with either Julian date or local habitat characteristics. 5. Fishes rapidly colonised isolated or dry habitats following floods. This was evidenced by the occurrence of fishes in intermittent reaches and the positive association between maximum daily discharge and colonisation events at both headwater sites. 6. Our study suggests floods allow dispersal into intermittent habitats with little or no downstream displacement of fishes. Movement of fishes among habitats during flooding highlights the importance of maintaining connectivity of stream networks of low to medium order prairie streams.}, keywords = {LTER-KNZ}, doi = {10.1111/j.1365-2427.2006.01640.x}, author = {Franssen, N.R. and K. B. Gido and Strakosh, T.R. and Bertrand, K.N. and Franssen, C.M. and Paukert, C.P. and Pitts, K.L. and Guy, C.S. and Tripe, J.A. and Shrank, S.J.} } @article {KNZ001152, title = {Evaluation of MODIS NPP and GPP products across multiple biomes}, journal = {Remote Sensing of Environment}, volume = {102}, year = {2006}, pages = {282 -292}, abstract = {Estimates of daily gross primary production (GPP) and annual net primary production (NPP) at the 1 km spatial resolution are now produced operationally for the global terrestrial surface using imagery from the MODIS (Moderate Resolution Imaging Spectroradiometer) sensor. Ecosystem-level measurements of GPP at eddy covariance flux towers and plot-level measurements of NPP over the surrounding landscape offer opportunities for validating the MODIS NPP and GPP products, but these flux measurements must be scaled over areas on the order of 25 km2 to make effective comparisons to the MODIS products. Here, we report results for such comparisons at 9 sites varying widely in biome type and land use. The sites included arctic tundra, boreal forest, temperate hardwood forest, temperate conifer forest, tropical rain forest, tallgrass prairie, desert grassland, and cropland. The ground-based NPP and GPP surfaces were generated by application of the Biome-BGC carbon cycle process model in a spatially-distributed mode. Model inputs of land cover and leaf area index were derived from Landsat data. The MODIS NPP and GPP products showed no overall bias. They tended to be overestimates at low productivity sites {\textemdash} often because of artificially high values of MODIS FPAR (fraction of photosynthetically active radiation absorbed by the canopy), a critical input to the MODIS GPP algorithm. In contrast, the MODIS products tended to be underestimates in high productivity sites {\textemdash} often a function of relatively low values for vegetation light use efficiency in the MODIS GPP algorithm. A global network of sites where both NPP and GPP are measured and scaled over the local landscape is needed to more comprehensively validate the MODIS NPP and GPP products and to potentially calibrate the MODIS NPP/GPP algorithm parameters.}, keywords = {LTER-KNZ, biomes, Global, Gross primary production, Landsat, MODIS, Monitoring, Net primary production, Validation}, doi = {10.1016/j.rse.2006.02.017}, author = {Turner, D.P. and Ritts, W.D. and Cohen, W.B. and Gower, S.T. and Running, SW. and Zhao, M. and Costa, M.H. and Kirschbaum, A. and J.M. Ham and Saleska, S. and Ahl, D.E.} } @article {KNZ001153, title = {MODIS land cover and LAI collection 4 product quality across nine sites in the western hemisphere}, journal = {IEEE Transactions in Geosciences and Remote Sensing}, volume = {44}, year = {2006}, pages = {1843 -1857}, abstract = {Global maps of land cover and leaf area index (LAI) derived from the Moderate Resolution Imaging Spectrometer (MODIS) reflectance data are an important resource in studies of global change, but errors in these must be characterized and well understood. Product validation requires careful scaling from ground and related measurements to a grain commensurate with MODIS products. We present an updated BigFoot project protocol for developing 25-m validation data layers over 49-km2 study areas. Results from comparisons of MODIS and BigFoot land cover and LAI products at nine contrasting sites are reported. In terms of proportional coverage, MODIS and BigFoot land cover were in close agreement at six sites. The largest differences were at low tree cover evergreen needleleaf sites and at an Arctic tundra site where the MODIS product overestimated woody cover proportions. At low leaf biomass sites there was reasonable agreement between MODIS and BigFoot LAI products, but there was not a particular MODIS LAI algorithm pathway that consistently compared most favorably. At high leaf biomass sites, MODIS LAI was generally overpredicted by a significant amount. For evergreen needleleaf sites, LAI seasonality was exaggerated by MODIS. Our results suggest incremental improvement from Collection 3 to Collection 4 MODIS products, with some remaining problems that need to be addressed}, keywords = {LTER-KNZ}, doi = {10.1109/TGRS.2006.876026}, author = {Cohen, W.B. and Maiersperger, T.K. and Turner, D.P. and Ritts, W.D. and Pflugmacher, D. and Kennedy, R.E. and Kirschbaum, A. and Running, S.W. and Costa, M. and Gower, S.T.} } @article {KNZ001054, title = {Molecular approach for assessing responses of microbial-feeding nematodes to burning and chronic nitrogen enrichment in a native grassland}, journal = {Molecular Ecology}, volume = {15}, year = {2006}, pages = {2601 -2609}, abstract = {A substantial proportion of the primary productivity in grassland ecosystems is allocated belowground, sustaining an abundant and diverse community of microbes and soil invertebrates. These belowground communities drive many important ecosystem functions and are responsive to a variety of environmental changes. Nematodes, an abundant and diverse component of grassland soil communities, are particularly responsive to altered environmental conditions, such as those associated with reduced fire frequency and nitrogen enrichment, with the most consistent responses displayed by microbial-feeding nematodes. However, much of the available research characterizing nematode responses to environmental change has been carried out at the taxonomic level of family or by broad trophic categories (e.g. fungivores, bacterivores). The extent to which differential responses to environmental change occurs at the genus level or below is unclear. Therefore, the objective of this study was to use molecular methods to quantify the response of microbial-feeding nematodes, at the lowest levels of taxonomic resolution, to nitrogen enrichment and changes in fire frequency. Using sequencing and quantitative polymerase chain reaction (PCR) probes for the 18S ribosomal RNA gene and the ITS1 region, we identified 19 microbial-feeding nematode taxa across four families. When nematodes were sampled across treatments, we found that some nematode taxa within a family responded similarly to nitrogen and burning treatments, while other taxa within the same family respond quite differently. Additionally, although nematodes from different families on average responded differently to nitrogen enrichment and burning, similar responses were seen in nematode taxa that span three taxonomic families. Thus, if nematodes are to be used as indicators of environmental change, care should be taken to assess the response at the lowest taxonomic level possible.}, keywords = {LTER-KNZ}, doi = {10.1111/j.1365-294X.2006.02971.x}, author = {Jones, K.L. and Todd, T.C. and Wall-Beam, J.L. and Coolon, J.D. and John M. Blair and Herman, M.A.} } @article {KNZ001048, title = {Non-neutral patterns of species abundance in grassland communities}, journal = {Ecology Letters}, volume = {9}, year = {2006}, pages = {15 -23}, abstract = {Although the distribution of plant species abundance in a Minnesota grassland was consistent with neutral theory, niche but not neutral mechanisms were supported by the ability of species traits to predict species abundances in three experimental grassland communities. In particular, data from 27 species grown in monoculture showed that species differed in a trait, R*, which is the level to which each species reduced the concentration of soil nitrate, the limiting soil nutrient and which is predicted to be inversely associated with competitive ability for nitrogen (N). In these N-limited habitats, species abundance ranks correlated with their predicted competitive ranks: low R* species, on average dominated. These correlations were significantly different than expected for neutral theory, which assumes the exchangeability of species traits. Additionally, we found that changes in relative abundance after environmental change (N-addition or disturbance) were not neutral but also were significantly associated with R*.}, keywords = {LTER-KNZ}, doi = {10.1111/j.1461-0248.2005.00836.x}, author = {Harpole, W.S. and Tilman, D.} } @article {KNZ001107, title = {Sentinel nematodes of land-use change and restoration in tallgrass prairie}, journal = {Journal of Nematology}, volume = {38}, year = {2006}, pages = {20 -27}, abstract = {Changes in land use and the associated changes in land cover are recognized as the most important component of human-induced global change. Much attention has been focused on deforestation, but grasslands are among the most endangered ecosystems on Earth. The North American tallgrass prairie is a dramatic example, exhibiting a greater than 95\% decline in historical area. Renewed interest in prairie conservation and restoration has highlighted the need for ecological indicators of disturbance and recovery in native systems, including the belowground component. The tallgrass prairie differs from the agricultural systems that have replaced it in having greater diversity and heterogeneity of resources, less physical soil disturbance (although other disturbances, such as fire and grazing, are prominent), and greater nitrogen limitation. Understanding the responses of nematode taxa to these characteristic differences is crucial to the development and improvement of community indices, but while knowledge of disturbance responses by individual taxa is accumulating, the level of necessary taxonomic resolution remains in question. Although nematode communities generally are better described for temperate grasslands than for other natural ecosystems, identification of sentinel taxa is further confounded by high levels of diversity, and both spatial and temporal heterogeneity.}, keywords = {LTER-KNZ}, url = {http://www.ncbi.nlm.nih.gov/pubmed/19259426}, author = {Todd, T.C. and Powers, T.O. and Mullin, P.G.} } @article {KNZ001042, title = {The use of pasture reflectance characteristics and arbuscular mycorrhizal root colonization to predict pasture characteristics of tallgrass prairie grazed by cattle and bison}, journal = {Grass and Forage Science}, volume = {61}, year = {2006}, pages = {32 -41}, abstract = {An experiment was conducted to evaluate the potential for using arbuscular mycorrhizal fungal (AMF) root colonization and pasture reflectance characteristics as indicators of changes in tallgrass prairie vegetation resulting from differences in grazing history. The experiment was conducted within the context of a separate long-term experiment in which eight 4{\textperiodcentered}9-ha pastures were grazed by either bison or cattle for nine consecutive years. Two separate ungrazed pastures were selected for comparison with grazed areas on the basis of similarity in burning regime, vegetation, soil and topographic characteristics. Four 45 m-long transects were located in the upland sites within each pasture, and four plots were clipped to ground level along each transect. Reflectance readings were taken with a hand-held radiometer at each sampling location and a soil core was collected within each plot for analysis of AMF root colonization. Reflectance readings at sixteen different wavelengths were used directly as inputs during multiple regression development or were transformed into each of three vegetation indices (normalized difference vegetation index, soil-adjusted vegetation index and wide-dynamic-range vegetation index) and used in simple linear regressions. Ungrazed pastures were characterized by higher (P < 0{\textperiodcentered}01) grass biomass, total biomass and canopy height than grazed pastures, but had a lower proportional abundance of forbs (P < 0{\textperiodcentered}01) and amounts of forb biomass (P = 0{\textperiodcentered}04). Species of herbivore did not significantly influence above-ground characteristics that were measured. In general, AMF root colonization was relatively small and was not significantly affected by treatment and, accordingly, the variation was insufficient to test its potential as an indicator of grazing effects on vegetation or its potential relationship with pasture reflectance. Multiple regression equations based on individual wavelength reflectance values explained significantly more of the variation in above-ground vegetation characteristics than did simple regressions using vegetation indices as predictor variables (r2 values from 0{\textperiodcentered}36 to 0{\textperiodcentered}46 vs. 0{\textperiodcentered}11 to 0{\textperiodcentered}27) and have the potential to predict above-ground vegetation characteristics in heterogeneous rangelands.}, keywords = {LTER-KNZ, Arbuscular mycorrhizal fungi, bison, Cattle, pasture characteristics, reflectance methods, tallgrass prairie}, doi = {10.1111/j.1365-2494.2006.00505.x}, author = {Villarreal, M. and Cochran, R.C. and Johnson, D.E. and Towne, E.G. and G.T. Wilson and D.C. Hartnett and Goodin, D.G.} } @article {KNZ001002, title = {Branching responses in Silphium integrifolium (Asteraceae) following mechanical or gall damage to apical meristems and neighbor removal}, journal = {American Journal of Botany}, volume = {92}, year = {2005}, pages = {954 -959}, abstract = {Branching in plants increases plant access to light and provides pathways for regrowth following damage or loss of the apical meristem. We conducted two experiments in an eastern Kansas tallgrass prairie to determine how apical meristem loss (by clipping), apical meristem damage (by insect galling), and increased light availability affected growth, reproduction, and branching in Silphium integrifolium (Asteraceae). The first experiment compared clipping with galling. Clipping increased axillary shoot numbers, while galling increased axillary shoot lengths, reflecting different allocation responses among damage types and inhibition of branching by galls. However, total capitulum production was less in all gall/clip treatments than in intact shoots. The second experiment compared clipping with mowing the surrounding vegetation to increase light availability. Mowing increased total leaf, total capitulum, and axillary shoot length and axillary capitulum production in clipped and unclipped plants and in large vs. small shoots. The presence of the neighboring canopy, not of an intact apical meristem, was therefore the stronger limitation on leaf and capitulum production. These experiments suggest that damage and light competition affected both branching frequency and the partitioning of resources among shoots, branches, and leaves. Because Silphium{\textquoteright}s growth form is widespread, similar responses may occur in other grassland forbs.}, keywords = {LTER-KNZ, Antistrophus silphii, apical dominance, Asteraceae, branching competition, galls, Herbivory, Konza Prairie}, doi = {10.3732/ajb.92.6.954}, author = {Fay, P.A. and Throop, H.L.} } @article {KNZ001147, title = {Carrion beetles (Coleoptera: Silphidae) of the Konza Prairie Biological Stationbeetles (Coleoptera: Silphidae) of the Konza Prairie Biological Station}, journal = {Journal of the Kansas Entomological Society}, volume = {78}, year = {2005}, pages = {124 -123}, abstract = {Pitfall traps were used to determine diversity, seasonality, and numbers of burying beetles on the Konza Prairie Biological Station (KPBS) during the summers of 1997 and 1998. Traps were baited with either beef liver (1997) or whole mouse carcasses (1997 and 1998); significantly more carrion beetles were found in traps baited with carcasses. A total of 1003 carrion beetles, representing 8 species, were trapped over the course of 1556 trap nights. One of these species, Necrophila americana Linneaus, had not previously been recorded in Riley County. One additional species was found at sites where pitfall trap bait was discarded, bringing the total number of KPBS silphid species to 9. Bait age was an important determinant in attracting silphids to pitfall traps, as numbers of beetles in the trap continued to increase with bait age up to 6 days. Grassland topography (upland vs. lowland trap sites) significantly affected the numbers of carrion beetles trapped. Grassland burn history did not affect number of carrion beetles trapped, but did seem to influence species diversity.}, keywords = {LTER-KNZ, Konza Prairie Biological Station, Nicrophorus marginatus, pitfall trap, seasonal occurrence, Silphidae}, doi = {10.2317/0305.06.1}, author = {Rintoul, D.A. and Krueger, L.M. and Woodard, C. and Throne, J.E.} } @article {KNZ00983, title = {Nitrogen enrichment causes minimal changes in arbuscular mycorrhizal colonization but shifts community composition - evidence from rDNA data}, journal = {Biology and Fertility of Soils}, volume = {41}, year = {2005}, pages = {217 -224}, abstract = {Intracellular arbuscular mycorrhizal (AM) colonization was compared between nitrogen (NH4NO3) fertilized (10 g N m-2) and nonfertilized tallgrass prairie plots. In the microscopic analyses of host roots, only intracellular coils showed an increasing trend as a result of N fertilization, whereas intracellular colonization by arbuscules, hyphae, or vesicles did not differ between the N treatments. Clone libraries established from pooled PCR products of AM fungi contained exclusively species of Glomus; no other genera were detected indicating that Glomus spp. dominated the host roots. Comparisons between observed and random topologies indicated that cloned sequence placement covaried with N treatment: unique clades within Glomus originated exclusively from N-fertilized or nonfertilized treatments. We conclude that the communities of dominant and most commonly occurring AM fungi changed in response to N amendment, although the root colonization showed minimal or no response.}, keywords = {LTER-KNZ, Arbuscular mycorrhiza, Nitrogen deposition, Ribosomal DNA, tallgrass prairie}, doi = {10.1007/s00374-005-0845-8}, author = {A. Jumpponen and Trowbridge, J. and Mandyam, K.G. and Johnson, L.C.} } @article {KNZ00975, title = {Vegetationtrends in tallgrass prairie from bison and cattle grazing}, journal = {Ecological Applications}, volume = {15}, year = {2005}, pages = {1550 -1559}, abstract = {Comparisons between how bison and cattle grazing affect the plant community are understood poorly because of confounding differences in how the herbivores are typically managed. This 10-year study compared vegetation changes in Kansas (USA) tallgrass prairie that was burned and grazed season-long at a moderate stocking rate by either bison or cattle. We held management practices constant between the herbivores and equalized grazing pressure by matching animals so that the total body mass in all pastures was similar each year. Trends in species cover and diversity indices in the bison and cattle pastures were compared with ungrazed prairie that also was burned annually. We found that little bluestem (Schizachyrium scoparium) cover decreased over time in bison pastures, and big bluestem (Andropogon gerardii) cover increased over time in cattle pastures. Grazing by either herbivore increased the canopy cover of annual forbs, perennial forbs, and cool-season graminoids, but both annual and perennial forb cover increased at a greater rate in bison pastures than in cattle pastures. Missouri goldenrod (Solidago missouriensis) and heath aster (Symphyotrichum ericoides) were primarily responsible for the increased forb cover in grazed pastures. Species richness at both small (10 m2) and large (200 m2) spatial scales increased at a greater rate in bison pastures than in cattle pastures, but richness did not change through time in ungrazed prairie. The number of annual forb species was significantly higher in bison pastures than in pastures grazed by cattle. Residual graminoid biomass at the end of the grazing season was lower in bison pastures than in cattle pastures, whereas forb residuum increased over time at a greater rate in pastures grazed by bison than in pastures grazed by cattle. Although bison and cattle differentially altered some vegetation components, the plant communities in bison and cattle pastures were 85\% similar after 10 years of grazing. We conclude that most measurable differences between bison-grazed and cattle-grazed pastures in tallgrass prairie are relatively minor, and differences in how the herbivores are typically managed may play a larger role in their impact on prairie vegetation than differences between the species.}, keywords = {LTER-KNZ}, doi = {10.1890/04-1958}, author = {Towne, E.G. and D.C. Hartnett and Cochran, R.C.} } @article {KNZ00925, title = {Carbon and nitrogen stoichiometry and nitrogen cycling rates in streams}, journal = {Oecologia}, volume = {140}, year = {2004}, pages = {458 -467}, abstract = {Stoichiometric analyses can be used to investigate the linkages between N and C cycles and how these linkages influence biogeochemistry at many scales, from components of individual ecosystems up to the biosphere. N-specific NH4 + uptake rates were measured in eight streams using short-term 15N tracer additions, and C to N ratios (C:N) were determined from living and non-living organic matter collected from ten streams. These data were also compared to previously published data compiled from studies of lakes, ponds, wetlands, forests, and tundra. There was a significant negative relationship between C:N and N-specific uptake rate; C:N could account for 41\% of the variance in N-specific uptake rate across all streams, and the relationship held in five of eight streams. Most of the variation in N-specific uptake rate was contributed by detrital and primary producer compartments with large values of C:N and small values for N-specific uptake rate. In streams, particulate materials are not as likely to move downstream as dissolved N, so if N is cycling in a particulate compartment, N retention is likely to be greater. Together, these data suggest that N retention may depend in part on C:N of living and non-living organic matter in streams. Factors that alter C:N of stream ecosystem compartments, such as removal of riparian vegetation or N fertilization, may influence the amount of retention attributed to these ecosystem compartments by causing shifts in stoichiometry. Our analysis suggests that C:N of ecosystem compartments can be used to link N-cycling models across streams.}, keywords = {LTER-KNZ, carbon, Carbon:Nitrogen ratio, nitrogen, stoichiometry, streams}, doi = {10.1007/s00442-004-1599-y}, author = {W. K. Dodds and Marti, E. and Tank, J. and Pontius, J.L. and Hamilton, S.K. and Grimm, N.B. and W.B. Bowden and W.H. McDowell and Peterson, B.J. and Valett, H.M. and Webster, J.R. and Gregory, S.} } @article {KNZ00917, title = {Convergence across biomes to a common rain-use efficiency}, journal = {Nature}, volume = {429}, year = {2004}, pages = {651 -654}, keywords = {LTER-KNZ}, doi = {10.1038/nature02561}, author = {Huxman, T.E. and M.D. Smith and Fay, P.A. and Alan K. Knapp and Shaw, M.R. and Loik, M.E. and Smith, S.D. and Tissue, D.T. and Zak, J.C. and Weltzin, J.F. and Pockman, W.T. and Sala, O.E. and Haddad, B.M. and Harte, J. and Koch, G.W. and Schwinning, S. and Small, E.E. and Williams, D.G.} } @article {KNZ00956, title = {Empirical comparison of Landsat 7 and IKONOS multispectral measurements for selected Earth Observation System (EOS) validation sites}, journal = {Remote Sensing of Environment}, volume = {88}, year = {2004}, pages = {80 -99}, abstract = {The Space Imaging IKONOS observatory may provide an important benefit in terrestrial scientific research. The five-band, 1 m panchromatic and 4 m multispectral measurements have the potential to provide a source of measurements to evaluate subpixel land cover variability in measurements from observatories such as Landsat 7 Enhanced Thematic Mapper Plus (ETM+) and Terra MODIS sensor. The IKONOS observations are at a spatial scale equivalent to field measurements typically carried out in ecological and land cover research. As such, the IKONOS observations may serve as a source of {\textquotedblleft}virtual{\textquotedblright} ground measurements, for the lower spatial resolution, global observatories. In this study we examine how well IKONOS sensor observations replicate Landsat 7 ETM+ visible/near infrared observations for selected Earth Observation System (EOS) validation sites in the United States. The sites examined{\textemdash}Beltsville, MD, Konza Prairie, KS, and Sevilleta, NM{\textemdash}sample the east{\textendash}west moisture gradient across the United States. Observations for each site were acquired, as nearly time-coincident as possible, from ETM+ and the IKONOS sensor, several times over the growing season. This was done to insure that we compared these two sensors over the widest range of observing conditions possible. We also examined IKONOS imagery from Phoenix, AZ, where Space Imaging had and had not applied a modulation transfer function compensation (MTFC) process. The MTFC is their standard product. We found that this product, at the original 4 m spatial resolution, appears to have minor radiometric artifacts as a result of the process. When the IKONOS observations were aggregated to 30 m, this problem was essentially absent, allowing us to proceed with the remainder of our study. We processed the IKONOS sensor and ETM+ measurements to produce close approximates of each other. Our processing steps included ortho-rectification, calibration to planetary reflectance, pixel alignment and pixel aggregation. We initially found radiometric differences between the two sensors that increased with increasing wavelength. Space Imaging updated their calibration information, based on analyses from NASA Stennis Space Center staff, which removed much of this discrepancy. We now find that the IKONOS red and near infrared measurements differ between the two sensors, with IKONOS generally producing higher reflectance in the red band and lower reflectance in the near infrared band than the Landsat 7 ETM+ sensor. This results in the IKONOS sensor producing lower spectral vegetation index measurements, for the same target, than ETM+, a measurement variation that has been observed between other sensors. We also encountered far more cirrus cloud (and shadow) contamination in these paired observations that we had expected. After careful initial selection, we lost over half of our image pairs from the analysis because of cirrus cloud contamination. We do not know whether this is simply because of the paired, comparative design of this study or whether it relates to the increased spatial and radiometric resolution of the IKONOS sensor. The results of this study not only provide a baseline assessment of IKONOS versus Landsat 7 ETM+ visible and near infrared measurements but also suggest some of the issues that need more attention when comparing other sensor systems as well as developing the design of future land observatories.}, keywords = {LTER-KNZ, ETM+, IKONOS, Landsat 7}, doi = {10.1016/j.rse.2003.07.009}, author = {Goward, S.N. and Davis, P.E. and Fleming, D. and Miller, L. and Townshend, J.R.} } @article {KNZ00937, title = {Interactive effects of burn regime and bison activity on tallgrass prairie vegetation}, journal = {American Midland Naturalist}, volume = {152}, year = {2004}, pages = {237 -247}, keywords = {LTER-KNZ}, author = {Trager, M. and G.T. Wilson and D.C. Hartnett} } @article {KNZ00881, title = {Assessing the response of terrestrial ecosystems to potential changes in precipitation}, journal = {BioScience}, volume = {53}, year = {2003}, pages = {941 -952}, abstract = {Changes in Earth{\textquoteright}s surface temperatures caused by anthropogenic emissions of greenhouse gases are expected to affect global and regional precipitation regimes. Interactions between changing precipitation regimes and other aspects of global change are likely to affect natural and managed terrestrial ecosystems as well as human society. Although much recent research has focused on assessing the responses of terrestrial ecosystems to rising carbon dioxide or temperature, relatively little research has focused on understanding how ecosystems respond to changes in precipitation regimes. Here we review predicted changes in global and regional precipitation regimes, outline the consequences of precipitation change for natural ecosystems and human activities, and discuss approaches to improving understanding of ecosystem responses to changing precipitation. Further, we introduce the Precipitation and Ecosystem Change Research Network (PrecipNet), a new interdisciplinary research network assembled to encourage and foster communication and collaboration across research groups with common interests in the impacts of global change on precipitation regimes, ecosystem structure and function, and the human enterprise.}, keywords = {LTER-KNZ, Community, ecosystem, global change, Precipitation, soil moisture}, doi = {doi: 10.1641/0006-3568(2003)053[0941:ATROTE]2.0.CO;2}, author = {Weltzin, J.F. and Loik, M.E. and Schwinning, S. and Williams, D.G. and Fay, P.A. and Haddad, B. and Harte, J. and Huxman, T.E. and Alan K. Knapp and Lin, G. and Pockman, W.T. and Shaw, M.R. and Small, E. and M.D. Smith and Tissue, D.T. and Zak, J.C.} } @article {KNZ00923, title = {Comparing denitrification estimates for a Texas estuary by using acetylene inhibition and membrane inlet mass spectrometry}, journal = {Applied and Environmental Microbiology}, volume = {69}, year = {2003}, pages = {5950 -5956}, abstract = {Characterizing denitrification rates in aquatic ecosystems is essential to understanding how systems may respond to increased nutrient loading. Thus, it is important to ensure the precision and accuracy of the methods employed for measuring denitrification rates. The acetylene (C2H2) inhibition method is a simple technique for estimating denitrification. However, potential problems, such as inhibition of nitrification and incomplete inhibition of nitrous oxide reduction, may influence rate estimates. Recently, membrane inlet mass spectrometry (MIMS) has been used to measure denitrification in aquatic systems. Comparable results were obtained with MIMS and C2H2 inhibition methods when chloramphenicol was added to C2H2 inhibition assay mixtures to inhibit new synthesis of denitrifying enzymes. Dissolved-oxygen profiles indicated that surface layers of sediment cores subjected to the MIMS flowthrough incubation remained oxic whereas cores incubated using the C2H2 inhibition methods did not. Analysis of the microbial assemblages before and after incubations indicated significant changes in the sediment surface populations during the long flowthrough incubation for MIMS analysis but not during the shorter incubation used for the C2H2 inhibition method. However, bacterial community changes were also small in MIMS cores at the oxygen transition zone where denitrification occurs. The C2H2 inhibition method with chloramphenicol addition, conducted over short incubation intervals, provides a cost-effective method for estimating denitrification, and rate estimates are comparable to those obtained by the MIMS method.}, keywords = {LTER-KNZ}, doi = {10.1128/AEM.69.10.5950-5956.2003}, author = {Bernot, M.J. and W. K. Dodds and Gardner, W.S. and McCarthy, M.J. and Sobolev, D. and Tank, J.L.} } @article {KNZ001150, title = {Comparisons of land cover and LAI estimates derived from ETM+ and MODIS for four sites in North America: a quality assessment of 2000/2001 provisional MODIS products}, journal = {Remote Sensing of Environment}, volume = {88}, year = {2003}, pages = {221 -362}, abstract = {The MODIS land science team produces a number of standard products, including land cover and leaf area index (LAI). Critical to the success of MODIS and other sensor products is an independent evaluation of product quality. In that context, we describe a study using field data and Landsat ETM+ to map land cover and LAI at four 49-km2 sites in North America containing agricultural cropland (AGRO), prairie grassland (KONZ), boreal needleleaf forest, and temperate mixed forest. The purpose was to: (1) develop accurate maps of land cover, based on the MODIS IGBP (International Geosphere{\textendash}Biosphere Programme) land cover classification scheme; (2) derive continuous surfaces of LAI that capture the mean and variability of the LAI field measurements; and (3) conduct initial MODIS validation exercises to assess the quality of early (i.e., provisional) MODIS products. ETM+ land cover maps varied in overall accuracy from 81\% to 95\%. The boreal forest was the most spatially complex, had the greatest number of classes, and the lowest accuracy. The intensive agricultural cropland had the simplest spatial structure, the least number of classes, and the highest overall accuracy. At each site, mapped LAI patterns generally followed patterns of land cover across the site. Predicted versus observed LAI indicated a high degree of correspondence between field-based measures and ETM+ predictions of LAI. Direct comparisons of ETM+ land cover maps with Collection 3 MODIS cover maps revealed several important distinctions and similarities. One obvious difference was associated with image/map resolution. ETM+ captured much of the spatial complexity of land cover at the sites. In contrast, the relatively coarse resolution of MODIS did not allow for that level of spatial detail. Over the extent of all sites, the greatest difference was an overprediction by MODIS of evergreen needleleaf forest cover at the boreal forest site, which consisted largely of open shrubland, woody savanna, and savanna. At the agricultural, temperate mixed forest, and prairie grassland sites, ETM+ and MODIS cover estimates were similar. Collection 3 MODIS-based LAI estimates were considerably higher (up to 4 m2 m-2) than those based on ETM+ LAI at each site. There are numerous probable reasons for this, the most important being the algorithms{\textquoteright} sensitivity to MODIS reflectance calibration, its use of a prelaunch AVHRR-based land cover map, and its apparent reliance on mainly red and near-IR reflectance. Samples of Collection 4 LAI products were examined and found to consist of significantly improved LAI predictions for KONZ, and to some extent for AGRO, but not for the other two sites. In this study, we demonstrate that MODIS reflectance data are highly correlated with LAI across three study sites, with relationships increasing in strength from 500 to 1000 m spatial resolution, when shortwave-infrared bands are included.}, keywords = {LTER-KNZ, BigFoot, ETM, IGBP, Land cover, Leaf area index, MODIS, Validation}, doi = {10.1016/j.rse.2003.06.006}, author = {Cohen, W.B. and Maiersperger, T.K. and Yang, Z. and Gower, S.T. and Turner, D.P. and Ritts, W.D. and Berterretche, M. and Running, S.W.} } @article {KNZ00860, title = {A cross-biome comparison of daily light use efficiency for gross primary production}, journal = {Global Change Biology}, volume = {9}, year = {2003}, pages = {383 -395}, abstract = {Vegetation light use efficiency is a key physiological parameter at the canopy scale, and at the daily time step is a component of remote sensing algorithms for scaling gross primary production (GPP) and net primary production (NPP) over regional to global domains. For the purposes of calibrating and validating the light use efficiency (εg) algorithms, the components of εg{\textendash} absorbed photosynthetically active radiation (APAR) and ecosystem GPP {\textendash} must be measured in a variety of environments. Micrometeorological and mass flux measurements at eddy covariance flux towers can be used to estimate APAR and GPP, and the emerging network of flux tower sites offers the opportunity to investigate spatial and temporal patterns in εg at the daily time step. In this study, we examined the relationship of daily GPP to APAR, and relationships of εg to climatic variables, at four micrometeorological flux tower sites {\textendash} an agricultural field, a tallgrass prairie, a deciduous forest, and a boreal forest. The relationship of GPP to APAR was close to linear at the tallgrass prairie site but more nearly hyperbolic at the other sites. The sites differed in the mean and range of daily εg, with higher values associated with the agricultural field than the boreal forest. εg decreased with increasing APAR at all sites, a function of mid-day saturation of GPP and higher εg under overcast conditions. εg was generally not well correlated with vapor pressure deficit or maximum daily temperature. At the agricultural site, a εg decline towards the end of the growing season was associated with a decrease in foliar nitrogen concentration. At the tallgrass prairie site, a decline in εg in August was associated with soil drought. These results support inclusion of parameters for cloudiness and the phenological status of the vegetation, as well as use of biome-specific parameterization, in operational εg algorithms.}, keywords = {LTER-KNZ, Primary production}, doi = {10.1046/j.1365-2486.2003.00573.x}, author = {Turner, D.P. and Urbanski, D. and D. Bremer and Wofsy, S.C. and Meyers, T. and Gower, S.T. and Gregory, M.} } @article {KNZ00839, title = {Disturbance dynamics and ecological response: the contribution of long-term ecological research}, journal = {BioScience}, volume = {53}, year = {2003}, pages = {46 -56}, abstract = {Long-term ecological research is particularly valuable for understanding disturbance dynamics over long time periods and placing those dynamics in a regional context. We highlighted three case studies from Long Term Ecological Research (LTER) Network sites that have contributed to understanding the causes and consequences of disturbance in ecological systems. The LTER Network significantly enhances the ability to study disturbance by (a) encompassing ecosystems subject to a wide range of disturbances, (b) providing a long-term baseline against which to detect change and measure ecosystem responses to disturbance, (c) permitting observation of slow or infrequent events, (d) facilitating the use of multiple research approaches, (e) providing a focus for modeling disturbance dynamics, and (f) contributing to land and resource management. Long-term research is crucial to understanding past, present, and future disturbance dynamics, and the LTER Network is poised to make continuing contributions to the understanding of disturbance.}, keywords = {LTER-KNZ, biotic invasion, fire, heterogeneity, hurricane, scale}, doi = { 10.1641/0006-3568(2003)053[0046:DDAERT]2.0.CO;2}, author = {Turner, M.G. and Scott. L. Collins and Lugo, A.L. and Magnuson, J.J. and Rupp, T.S. and Swanson, F.J.} } @article {KNZ00861, title = {Effects of fire, mowing and fertilization effects on density and biomass of macroinvertebrates in North American tallgrass prairie soils}, journal = {Soil Biology \& Biochemistry}, volume = {35}, year = {2003}, pages = {1079 -1093}, abstract = {The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.}, keywords = {LTER-KNZ, biomass, Cicadidae, Curculionidae, disturbance, earthworms, Elateridae, Fertilization, Fertilizer, fire, grassland, insect herbivores, nitrogen, Phosphorus, Scarabaeidae}, doi = {10.1016/S0038-0717(03)00153-6}, author = {Callaham, M.A. Jr. and John M. Blair and T.C. Todd and Kitchen, D.J. and M.R. Whiles} } @article {KNZ00870, title = {Factors affecting ammonium uptake in streams - an inter-biome perspective}, journal = {Freshwater Biology}, volume = {48}, year = {2003}, pages = {1329 -1352}, abstract = {1. The Lotic Intersite Nitrogen eXperiment (LINX) was a coordinated study of the relationships between North American biomes and factors governing ammonium uptake in streams. Our objective was to relate inter-biome variability of ammonium uptake to physical, chemical and biological processes. 2. Data were collected from 11 streams ranging from arctic to tropical and from desert to rainforest. Measurements at each site included physical, hydraulic and chemical characteristics, biological parameters, whole-stream metabolism and ammonium uptake. Ammonium uptake was measured by injection of 15N-ammonium and downstream measurements of 15N-ammonium concentration. 3. We found no general, statistically significant relationships that explained the variability in ammonium uptake among sites. However, this approach does not account for the multiple mechanisms of ammonium uptake in streams. When we estimated biological demand for inorganic nitrogen based on our measurements of in-stream metabolism, we found good correspondence between calculated nitrogen demand and measured assimilative nitrogen uptake. 4. Nitrogen uptake varied little among sites, reflecting metabolic compensation in streams in a variety of distinctly different biomes (autotrophic production is high where allochthonous inputs are relatively low and vice versa). 5. Both autotrophic and heterotrophic metabolism require nitrogen and these biotic processes dominate inorganic nitrogen retention in streams. Factors that affect the relative balance of autotrophic and heterotrophic metabolism indirectly control inorganic nitrogen uptake.}, keywords = {LTER-KNZ}, doi = {10.1046/j.1365-2427.2003.01094.x}, author = {Webster, J.R. and P. Mulholland and Tank, J.L. and Valett, H.M. and W. K. Dodds and Peterson, B.J. and W.B. Bowden and Dahm, C.N. and S.E.G. Findlay and Gregory, S.V. and Grimm, N.B. and Hamilton, S.K. and Johnson, S.L. and Marti, E. and W.H. McDowell and Meyer, J.L. and Morrall, D.D. and Thomas, S.A. and Wollheim, W.M.} } @article {KNZ00845, title = {The importance of land-use legacies to ecology and conservation}, journal = {BioScience}, volume = {53}, year = {2003}, pages = {77 -88}, abstract = {Recognition of the importance of land-use history and its legacies in most ecological systems has been a major factor driving the recent focus on human activity as a legitimate and essential subject of environmental science. Ecologists, conservationists, and natural resource policymakers now recognize that the legacies of land-use activities continue to influence ecosystem structure and function for decades or centuries{\textemdash}or even longer{\textemdash}after those activities have ceased. Consequently, recognition of these historical legacies adds explanatory power to our understanding of modern conditions at scales from organisms to the globe and reduces missteps in anticipating or managing for future conditions. As a result, environmental history emerges as an integral part of ecological science and conservation planning. By considering diverse ecological phenomena, ranging from biodiversity and biogeochemical cycles to ecosystem resilience to anthropogenic stress, and by examining terrestrial and aquatic ecosystems in temperate to tropical biomes, this article demonstrates the ubiquity and importance of land-use legacies to environmental science and management.}, keywords = {LTER-KNZ, conservation, disturbance, ecosystem process, Land use, natural resource management}, doi = {10.1641/0006-3568(2003)053[0077:TIOLUL]2.0.CO;2}, author = {D.R. Foster and Swanson, F. and Aber, J. and I. Burke and Brokaw, N. and Tilman, D. and Alan K. Knapp} } @article {KNZ00869, title = {Responses of heterotrophic and autotrophic biofilms to nutrients in ten streams}, journal = {Freshwater Biology}, volume = {48}, year = {2003}, pages = {1031 -1049}, abstract = {1. Nutrient diffusing substrata were used to determine the effect of added inorganic nitrogen (N) and phosphorus (P) on the development of epilithic and epixylic biofilms in 10 North American streams. Four treatments of diffusing substrata were used: Control (agar only), N addition (0.5 m NaNO3), P addition (0.5 m KH2PO4), and N + P combined (0.5 m NaNO3 + 0.5 m KH2PO4). Agar surfaces were covered with glass fibre filters (for epilithon) or discs of untreated white oak wood veneer (for epixylon). 2. We found that if algae showed significant response to nutrient addition, N limitation (either N alone or N with P) was the most frequent response both on GF/F filters and on wood. Despite the low dissolved nutrient concentrations in our study streams, more than a third of the streams did not show any response to N or P addition. In fact, P was never the sole limiting nutrient for algal biofilms in this study. 3. Nutrient addition influenced algal colonisation of inorganic versus organic substrata in different ways. The presence of other biofilm constituents (e.g. fungi or bacteria) may influence whether algal biomass on wood increased in response to nutrient addition. Algae on organic and inorganic substrata responded similarly to nutrient addition in only one stream. 4. Fungal biomass on wood was nutrient limited in six of 10 study streams. N limitation of fungal biomass (with or without secondary P limitation) was most frequent, but P limitation did occur in two streams. 5. Our results show that biomass responses to nutrient addition by the heterotrophic and autotrophic components of the epixylic biofilm were different, though both experienced the same stream nutrient conditions. For algae and fungi growing on wood, limiting nutrients were rarely similar. Only three of nine streams showed the same biomass response to nutrient addition, including two that showed no significant change in biomass despite added nutrients.}, keywords = {LTER-KNZ}, doi = {10.1046/j.1365-2427.2003.01067.x}, author = {Tank, J.L. and W. K. Dodds} } @article {KNZ00846, title = {Vegetation dynamics from annually burning tallgrass prairie in different seasons}, journal = {Journal of Range Management}, volume = {56}, year = {2003}, pages = {185 -192}, abstract = {Traditional perception of how tallgrass prairie responds to fire at times other than late spring is either anecdotal or extrapolated from studies that lack spatial or temporal variability. Therefore, we evaluated patterns of change in vegetation cover, species richness, diversity, and aboveground biomass production on 2 different topographic positions from ungrazed watersheds that were burned annually for 8 years in either autumn (November), winter (February), or spring (April). Topoedaphic factors influenced the response patterns of some species to seasonal fire, although differences were primarily in the rate of change. Annual burning in autumn and winter produced similar trends through time for most species. Big bluestem (Andropogon gerardii Vitman) cover increased with all burn regimes, whereas indiangrass [Sorghastrum nutans (L.) Nash] increased only with spring burning. Repeated autumn and winter burning eventually increased perennial forb cover, with the largest increases occurring in heath aster [Symphyotrichum ericoides (L.) Nesom], aromatic aster [S. oblognifolium (Nutt.) Nesom], tall goldenrod (Solidago canadensis L.), and legumes. Species richness increased (P<0.001) through time with spring and winter burning, but was similar among all burn treatments after 8 years of annual fire. Average grass and forb biomass did not differ among burn seasons on either topographic position, although interannual biomass production fluctuated inconsistently with time of burn. Our findings contrast with many of the conventional views of how tallgrass prairie vegetation responds to seasonal fire and challenges traditional recommendations that burning should only occur in late spring.}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.2307/4003903}, author = {Towne, E.G. and Kemp, K.E.} } @inbook {KNZ0010, title = {Applications of advanced technologies in studying and managing grassland landscape integrity}, booktitle = {Integrating Landscape Ecology into Natural Resource Management}, year = {2002}, pages = {390 -411}, publisher = {Cambridge University Press}, organization = {Cambridge University Press}, address = {Cambridge, U.K.}, keywords = {LTER-KNZ, grassland, landscape}, author = {Hoch, G. and B. Brock and J. M. Briggs}, editor = {Liu, J. and Taylor, W.W.} } @article {KNZ00810, title = {Can uptake length in streams be determined by nutrient addition experiments? Results from an inter-biome comparison study}, journal = {Journal of the North American Benthological Society}, volume = {21}, year = {2002}, pages = {544 -560}, abstract = {Nutrient uptake length is an important parameter for quantifying nutrient cycling in streams. Although nutrient tracer additions are the preferred method for measuring uptake length under ambient nutrient concentrations, short-term nutrient addition experiments have more frequently been used to estimate uptake length in streams. Theoretical analysis of the relationship between uptake length determined by nutrient addition experiments (SW') and uptake length determined by tracer additions (SW) predicted that SW' should be consistently longer than SW, and that the overestimate of uptake length by SW' should be related to the level of nutrient addition above ambient concentrations and the degree of nutrient limitation. To test these predictions, we used data from an interbiome study of NH4+ uptake length in which 15NH4+ tracer and short-term NH4+ addition experiments were performed in 10 streams using a uniform experimental approach. The experimental results largely confirmed the theoretical predictions: SW' was consistently longer than SW and SW':SW ratios were directly related to the level of NH4+ addition and to indicators of N limitation. The experimentally derived SW':SW ratios were used with the theoretical results to infer the N limitation status of each stream. Together, the theoretical and experimental results showed that tracer experiments should be used whenever possible to determine nutrient uptake length in streams. Nutrient addition experiments may be useful for comparing uptake lengths between different streams or different times in the same stream, however, provided that nutrient additions are kept as low as possible and of similar magnitude.}, keywords = {LTER-KNZ, ammonium, nitrogen limitation, nutrient cycling, nutrient spiraling, stream, uptake length}, doi = {10.2307/1468429}, author = {Mulholland, P.J. and Tank, J.L. and Webster, J.R. and W.B. Bowden and W. K. Dodds and Gregory, S.V. and Grimm, N.B. and Hamilton, S.K. and Johnson, S.L. and Marti, E. and W.H. McDowell and Merriam, J. and Meyer, J.L. and Peterson, B.J. and Valett, H.M. and Wollheim, W.M.} } @article {KNZ00807, title = {A cross-system comparison of bacterial and fungal biomass in detritus pools of headwater streams}, journal = {Microbial Ecology}, volume = {43}, year = {2002}, pages = {55 -66}, keywords = {LTER-KNZ}, doi = {10.1007/s00248-001-1020-x}, author = {Findlay, S.E.G. and Tank, J. and Dye, S. and Vallett, H.M. and Mulholland, P.J. and W.H. McDowell and Johnson, S. and Hamilton, S.K. and Edmonds, J. and W. K. Dodds and W.B. Bowden} } @inbook {KNZ00986, title = {Fire behaviour as a key factor in the fire ecology of African grasslands and savannas}, booktitle = {Forest Fire Research and Wildland Fire}, year = {2002}, pages = {204 -}, publisher = {Millpress, Rotterdam Netherlands}, organization = {Millpress, Rotterdam Netherlands}, abstract = {

The effect of fire on natural ecosystems involves the response of living organisms to the release of heat energy through the combustion of plant material. The manner in which and the factors that influence the release of heat energy, involves the study of fire behaviour. In Africa there is a serious deficiency of knowledge concerning the behaviour of fires and this is particularly applicable to the savanna and grassland areas of the continent. Virtually no attempt has been made to quantify the dynamics of the release of heat energy during a fire and the subsequent response of plants to it. The determination of such relationships helps explain many of the apparently inexplicable effects of fire that are often cited in the literature. Research on the effects of fire has been conducted throughout the grassland and savanna areas of Africa, particularly in southern Africa, since the early period of the 20th century. An interesting feature about these early investigations and subsequent research up until 1971, was that it focused on the effects of season and frequency of burning on the forage production potential of the grass sward and the ratio of bush to grass in savanna areas However, in 1971 a conference was convened in the United States of America in Florida, by the Tall Timbers Research Station on the theme of \"Fire in Africa\". The major benefit that accrued from this conference was the realization that in Africa the study of fire behaviour and its effects on the ecosystem, as described by type and intensity of fire, had been largely ignored in all the fire research that had been conducted up until that time. As a consequence a research program was initiated in South Africa and later extended to East Africa, to characterise the behaviour of fires burning in savanna and grassland vegetation and determine the effect of type and intensity of fire on the vegetation. The overall effect of type of fire is that surface head fires and crown fires have the least effect on grasses and have the potential to have the greatest effect on trees. This is because the heat is released above ground level away from the growing points of the grasses and closest to the growing points of the trees. Conversely, surface back fires have the opposite effect on grass and tree vegetation. This is because the heat is released close to ground level where the growing points of grasses are located and away from the growing points of the trees in the canopy. The overall effect of fire intensity is that grasses are generally not sensitive to increasing fire intensities because their growing points are located close to ground level away from the release of heat energy. Conversely trees are sensitive to increasing fire intensities because their growing points are generally exposed to the release of heat energy in the canopy of the trees. These effects explain why intense fires favour the development of grassland and open savannas and vice versa. The behaviour of surface head and back fires is currently being compared in southern African savannas and tall grass prairies in North America and results indicate that fires burning in grass dominated communities behave similarly and may therefore have similar effects on grass and tree vegetation globally.

}, keywords = {LTER-KNZ, African grasslands, American prairies, fire, Savannas}, author = {Trollope, W.S.W. and Trollope, L.A. and D.C. Hartnett}, editor = {Viegas, D.X.} } @article {KNZ00806, title = {N uptake as a function of concentration in streams}, journal = {Journal of the North American Benthological Society}, volume = {21}, year = {2002}, pages = {206 -220}, abstract = {Detailed studies of stream N uptake were conducted in a prairie reach and gallery forest reach of Kings Creek on the Konza Prairie Biological Station. Nutrient uptake rates were measured with multiple short-term enrichments of NO3- and NH4+ at constant addition rates in the spring and summer of 1998. NH4+ uptake was also measured with 15N-NH4+ tracer additions and short-term unlabeled NH4+ additions at 12 stream sites across North America. Concurrent addition of a conservative tracer was used to account for dilution in all experiments. NH4+ uptake rate per unit area (Ut) was positively correlated to nutrient concentration across all sites (r2 = 0.41, log{\textendash}log relationship). Relationships between concentration and Ut were used to determine whether the uptake was nonlinear (i.e., kinetic uptake primarily limited by the biotic capacity of microorganisms to accumulate nutrients) or linear (e.g., limited by mass transport into stream biofilms). In all systems, Ut was lower at ambient concentrations than at elevated concentrations. Extrapolation from uptake measured from a series of increasing enrichments could be used to estimate ambient Ut. Linear extrapolation of Ut assuming the relationship passes through the origin and rates measured at 1 elevated nutrient concentration underestimated ambient Ut by \~{}3-fold. Uptake rates were saturated under some but not all conditions of enrichment; in some cases there was no saturation up to 50 μmol/L. The absolute concentration at which Ut was saturated in Kings Creek varied among reaches and nutrients. Uptake rates of NH4+ at ambient concentrations in all streams were higher than would be expected, assuming Ut does not saturate with increasing concentrations. At ambient nutrient concentrations in unpolluted streams, Ut is probably limited to some degree by the kinetic uptake capacity of stream biota. Mass transfer velocity from the water column is generally greater than would be expected given typical diffusion rates, underscoring the importance of advective transport. Given the short-term spikes in nutrient concentrations that can occur in streams (e.g., in response to storm events), Ut may not saturate, even at high concentrations.}, keywords = {LTER-KNZ, advective transport, ammonium, areal uptake, benthos, kinetics, mass transport, Nitrate, nitrogen}, doi = {10.2307/1468410}, author = {W. K. Dodds and L{\'o}pez, A.J. and W.B. Bowden and Gregory, S. and Grimm, N.B. and Hamilton, S.K. and Hershey, A.E. and Marti, E. and W.B. McDowell and Meyer, J.L. and Morrall, D. and Mulholland, P.J. and Peterson, B.J. and Tank, J.L. and van der Hoek, D.C.J. and Webster, J.R. and Wollheim, W.} } @article {KNZ00831, title = {Phrynosoma cornutum (Texas horned lizard) reproduction}, journal = {Herpetological Review}, volume = {33}, year = {2002}, pages = {308 -309}, keywords = {LTER-KNZ}, author = {Owens, A. and Trager, M. and Horne, E.} } @article {KNZ00837, title = {Recovery of three fish species to flood and seasonal drying in a tallgrass prairie stream}, journal = {Transactions of the Kansas Academy of Science}, volume = {105}, year = {2002}, pages = {209 -218}, abstract = {The recovery of three fish species following a catastrophic flood (>50 y recurrence interval) and seasonal drying were studied in Kings Creek basin at the Konza Prairie Biological Station in northeastern Kansas. Fish collected from three tallgrass prairie headwater springs were marked and recaptured to determine if headwater springs were a source of fish recolonizing intermittent sections downstream and to estimate population sizes in the headwater springs. Three fish species (Campostoma anomalum, Phoxinus erythrogaster, and Etheostoma spectabile) were collected. Catch rates and population estimates of fish nine days post-flood were approximately half of the values obtained during subsequent sampling periods. Recolonization of an intermittent section was primarily by age-0 fish that seemingly were displaced downstream by flood events. The distribution of fish within the upper subbasins of the South Branch of Kings Creek was limited to perennial spring-fed reaches. The short duration of continuous flow and regular drying in these tributaries might limit the dispersal of individuals between populations in this landscape.}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1660/0022-8443(2002)105[0209:ROTFST]2.0.CO;2}, author = {Fritz, K.M. and Tripe, J.A. and Guy, C.S.} } @article {KNZ00818, title = {Vascular plants of Konza Prairie Biological Station: An annotated checklist of species in a Kansas tallgrass prairie}, journal = {Sida}, volume = {20}, year = {2002}, pages = {269 -294}, abstract = {The native and naturalized vascular plants of Konza Prairie Biological Station, a 3487-ha tallgrass prairie research site located in the Flint Hills of northeastern Kansas, are listed along with their primary habitat, relative abundance, flowering period, and life span. After more than 25 years of collections, the known vascular flora of Konza Prairie consists of 576 species, representing 336 genera and 96 families. Families with the most species are Poaceae (84), Asteraceae (79), Fabaceae (49), and Cyperaceae (33). Non-native species (n = 96) comprise 16.7\% of the total flora. When categorized by life span, 64.6\% of all species are perennials, 31.3\% are annuals, and 4.2\% are biennials. Species that are characteristically associated with a prairie habitat comprise 40.6\% of the flora, followed by species in disturbed (22.4\%), woodland (22.2\%), and wetland (14.8\%) habitats. In the prairie habitat, 16.2\% of the species are grasses and 76.9\% are herbaceous forbs. The C$^{4}$ photosynthetic pathway occurs in 59.5\% of all grass species and in 70.8\% of the annual grasses. The diversified habitats created by management and research activities on Konza Prairie provide a flora richness that is likely greater than that of any other area of comparable size in the Great Plains region.}, keywords = {LTER-KNZ, Biodiversity, prairie flora, Species richness, tallgrass prairie, vascular plant survey}, url = {http://www.jstor.org/stable/41968021}, author = {Towne, E.G.} } @article {KNZ00783, title = {Control of nitrogen export from watersheds by headwater streams}, journal = {Science}, volume = {292}, year = {2001}, pages = {86 -90}, abstract = {A comparative 15N-tracer study of nitrogen dynamics in headwater streams from biomes throughout North America demonstrates that streams exert control over nutrient exports to rivers, lakes, and estuaries. The most rapid uptake and transformation of inorganic nitrogen occurred in the smallest streams. Ammonium entering these streams was removed from the water within a few tens to hundreds of meters. Nitrate was also removed from stream water but traveled a distance 5 to 10 times as long, on average, as ammonium. Despite low ammonium concentration in stream water, nitrification rates were high, indicating that small streams are potentially important sources of atmospheric nitrous oxide. During seasons of high biological activity, the reaches of headwater streams typically export downstream less than half of the input of dissolved inorganic nitrogen from their watersheds.}, keywords = {LTER-KNZ}, doi = {10.1126/science.1056874}, author = {Peterson, B.J. and Wollheim, W.M. and Mulholland, P.J. and Webster, J.R. and Meyer, J.L. and Tank, J.L. and Marti, E. and W.B. Bowden and Valett, H.M. and Hershey, A.E. and W.H. McDowell and W. K. Dodds and Hamilton, S.K. and Gregory, S. and Morrall, D.D.} } @article {KNZ00780, title = {Inter-biome comparison of factors controlling stream metabolism}, journal = {Freshwater Biology}, volume = {46}, year = {2001}, pages = {1503 -1517}, abstract = {1. We studied whole-ecosystem metabolism in eight streams from several biomes in North America to identify controls on the rate of stream metabolism over a large geographic range. The streams studied had climates ranging from tropical to cool-temperate and from humid to arid and were all relatively uninfluenced by human disturbances. 2. Rates of gross primary production (GPP), ecosystem respiration (R) and net ecosystem production (NEP) were determined using the open-system, two-station diurnal oxygen change method. 3. Three general patterns in metabolism were evident among streams: (1) relatively high GPP with positive NEP (i.e. net oxygen production) in early afternoon, (2) moderate primary production with a distinct peak in GPP during daylight but negative NEP at all times and (3) little or no evidence of GPP during daylight and a relatively constant and negative NEP over the entire day. 4. Gross primary production was most strongly correlated with photosynthetically active radiation (PAR). A multiple regression model that included log PAR and stream water soluble reactive phosphorus (SRP) concentration explained 90\% of the variation in log GPP. 5. Ecosystem respiration was significantly correlated with SRP concentration and size of the transient storage zone and, together, these factors explained 73\% of the variation in R. The rate of R was poorly correlated with the rate of GPP. 6. Net ecosystem production was significantly correlated only with PAR, with 53\% of the variation in log NEP explained by log PAR. Only Sycamore Creek, a desert stream in Arizona, had positive NEP (GPP: R > 1), supporting the idea that streams are generally net sinks rather than net sources of organic matter. 7. Our results suggest that light, phosphorus concentration and channel hydraulics are important controls on the rate of ecosystem metabolism in streams over very extensive geographic areas.}, keywords = {LTER-KNZ}, doi = {10.1046/j.1365-2427.2001.00773.x}, author = {Mulholland, P.J. and Fellows, C.S. and Tank, J.L. and Grimm, N.B. and Webster, J.R. and Hamilton, S.K. and Marti, E. and L.R. Ashkenas and W.B. Bowden and W. K. Dodds and W.H. McDowell and Paul, M.J. and Peterson, B.J.} } @article {KNZ00750, title = {Prairie vegetation and soil nutrient responses to ungulate carcasses}, journal = {Oecologia}, volume = {122}, year = {2000}, pages = {232 -239}, abstract = {The impact of large ungulate carcasses on grassland dynamics was investigated by monitoring vegetation and soil nutrients in 50-cm circular zones around the center of bison (Bos bison), cattle (B. taurus), and deer (Odocoileus virginianus) carcasses. An ungulate carcass creates an intense localized disturbance that varies with animal size and the season of death. Unlike other natural disturbances, carcasses deposit a concentrated pulse of nutrients into the soil. One year after death, inorganic nitrogen concentrations were significantly higher in the inner 50 cm at both adult and juvenile carcass sites than in surrounding prairie. Areas around a carcass became zones of fertility that favored different components of the vegetation and stimulated biomass production. Species richness and diversity at the center of carcass sites were lowest 1 year after death, but increased significantly in subsequent years. However, warm-season perennial grasses declined near the center of carcass sites and did not recover. Five years after death, ungulate carcass sites remained disturbed patches that harbored vegetation characteristically different in composition and stature from surrounding prairie. By providing a niche for species not normally found in undisturbed prairie, carcasses increased community heterogeneity and may play an important role in adding spatial complexity to grassland ecosytems.}, keywords = {LTER-KNZ, Carrion, disturbance, Soil nutrients, succession, tallgrass prairie}, doi = {10.1007/PL00008851}, author = {Towne, E.G.} } @article {KNZ00731, title = {Quantification of the nitrogen cycle in a prairie stream}, journal = {Ecosystems}, volume = {3}, year = {2000}, pages = {574 -589}, abstract = {Nitrogen (N) was added for 35 days in the form of 15NH4Cl to Kings Creek on Konza Prairie, Kansas. Standing stocks of N in key compartments (that is, nutrients, detritus, organisms) were quantified, and the amount of labeled N entering the compartments was analyzed. These data were used to calculate turnover and flux rates of N cycling through the food web, as well as nutrient transformation rates. Inorganic N pools turned over much more rapidly in the water column of this stream than in pelagic systems where comparable measurements have been made. As with other systems, the mass of ammonium was low but it was the key compartment mediating nutrient flux through the ecosystem, whereas dissolved organic N, the primary component of N flux through the system, is not actively cycled. Nitrification was also a significant flux of N in the stream, with rates in the water column and surface of benthos accounting for approximately 10\% of the total ammonium uptake. Primary consumers assimilated 67\% of the inorganic N that entered benthic algae and microbes. Predators acquired 23\% of the N that consumers obtained. Invertebrate collectors, omnivorous crayfish (Orconectes spp.), and invertebrate shredders dominated the N flux associated with primary consumers. Mass balance calculations indicated that at least 23\% of the 309 mg of 15N added during the 35 days of release was retained within the 210-m stream reach during the release. Overall, the rates of turnover of N in organisms and organic substrata were significantly greater when C:N was low. This ratio may be a surrogate for biological activity with regard to N flux in streams.}, keywords = {LTER-KNZ, aquatic insects, C:N ratio, nitrogen cycle, nitrogen export, stream, Trophic structure}, doi = {10.1007/s100210000050}, author = {W. K. Dodds and Evans-White, M.A. and N.M. Gerlanc and Gray, L. and Gudder, D.A. and Kemp, M.J. and Lo{\textquoteright}pez, A.L. and Stagliano, D. and Strauss, E. and Tank, J.L. and M.R. Whiles and Wollheim, W.} } @inbook {KNZ00721, title = {Responses of grassland soil invertebrates to natural and anthropogenic disturbances}, booktitle = {Invertebrates as Webmasters in Ecosystems}, year = {2000}, pages = {43 -71}, publisher = {CAB International Press}, organization = {CAB International Press}, address = {New York, NY}, abstract = {his chapter aims to (1) summarize the major factors influencing invertebrate abundance and distribution in tallgrass prairie soils, focusing on the responses of selected soil invertebrate groups to natural disturbances (such as fire, grazing and drought); (2) identify potential linkages between changes in soil communities and the effects of disturbances on key plant and soil characteristics or processes; and (3) to discuss potential effects of novel anthropogenic perturbations (altered amounts of precipitation, elevated CO2 and increased N inputs) on soil communities and processes. It focuses on North American tallgrass prairies and draws upon studies undertaken at the Konza Prairie Long-Term Ecological Research site, with results from other grasslands where appropriate.}, keywords = {LTER-KNZ}, doi = {10.1079/9780851993942.0043}, author = {John M. Blair and Todd, T.C. and Callaham, M.A.}, editor = {Coleman, D.C. and Hendrix, P.F.} } @article {KNZ00751, title = {Themeda quadrivalvis (Poaceae: Andropogoneae) in Kansas: An exotic plant introduced from birdseed}, journal = {Sida}, volume = {19}, year = {2000}, pages = {201 -203}, keywords = {LTER-KNZ}, url = {http://www.jstor.org/stable/41967774}, author = {Towne, E.G. and Barnard, I.} } @article {KNZ00716, title = {Bison performance and productivity on tallgrass prairie}, journal = {Southwestern Naturalist}, volume = {44}, year = {1999}, pages = {361 -366}, abstract = {Productivity and performance were evaluated over a 4-year period for a herd of nonsupplemented bison (Bos bison) at the Konza Prairie Research Natural Area in northeastern Kansas. Calving rates ranged from 65.7\% to 79.2\%, with an average of 74.4\%. Out of 317 calves born, 47.3\% were male and 52.7\% were female. Numbers of male and female calves born each year did not deviate from an expected 50:50 ratio except in 1997. At 6 months of age, male bison calves were significantly heavier than female calves. By 7.5 years of age, females weighed an average of 455 kg, and males averaged 727 kg. Male and female calves gained an average of 2.6\% of their body mass over their first winter, but all other animals lost an average of 11.3\% of their body mass over winter. All winters were relatively mild during this study, and mass losses for different age and sex groups did not differ significantly among years. Performance and productivity data for the Konza Prairie bison provide a benchmark for comparison with other herds.}, keywords = {LTER-KNZ, tallgrass prairie}, url = {http://www.jstor.org/stable/30055232}, author = {Towne, E.G.} } @article {KNZ00715, title = {Effects of altered soil water availability on a tallgrass prairie nematode community}, journal = {Applied Soil Ecology}, volume = {13}, year = {1999}, pages = {45 -55}, abstract = {Climate change predictions for the Great Plains region of North America include reduced growing season precipitation. The consequence of this prediction for soil fauna and belowground processes was investigated at two spatial scales by integrating experimental manipulation of soil moisture levels with natural variation in soil-water availability. Experiments consisted of (1) reciprocal core transplants across a regional precipitation gradient and (2) supplemental irrigation applied across a local topographic gradient. This report examines functional-level responses by the tallgrass prairie nematode community to differences in soil moisture levels over a four-year period. Effects on nematode community structure were complex and dependent upon nematode trophic habit and depth in the soil profile. The strongest and most consistent responses to changes in soil-water availability were displayed by herbivorous taxa, with 71\% higher densities observed under wetter soil conditions across experiments and years. Responses of microbial-feeding nematodes were more variable, with lower densities observed, in some cases, in the presence of experimentally-increased soil moisture levels. Effects of regional differences in soil-water availability on the nematode community were uniformly restricted to depths >20 cm. Community responses to short-term changes in soil moisture were not consistent with patterns in community structure developed under different natural moisture regimes, suggesting divergent short-term and long-term responses of belowground biota and processes to changes in soil-water availability.}, keywords = {LTER-KNZ, Climate change, community structure, Nematode, soil moisture, tallgrass prairie}, doi = {10.1016/S0929-1393(99)00022-0}, author = {Todd, T.C. and John M. Blair and Milliken, G.A.} } @article {KNZ00714, title = {Effects of fire, browsers, and gallers on New Jersey Tea (Ceanothus herbaceous) growth and reproduction}, journal = {American Midland Naturalist}, volume = {141}, year = {1999}, pages = {51 -58}, abstract = {Woody plant species in grassland ecosystems can be subjected to damage from fire and multiple herbivore species, but interactions between fire and herbivory can modify their separate impacts on woody plant life histories. We studied how galling (by Periploca ceanothiella, Lepidoptera: Cosmopterigidae), deer browsing (Odocoilius virginianus) and fire affected the growth and reproduction of the woody shrub Ceanothus herbaceous (Rhamnaceae) on a burned and an unburned site at Konza Prairie Research Natural Area in eastern Kansas. Fire was the major influence on C. herbaceous growth, causing plants to produce long unbranched vegetative ramets from protected belowground meristems, while unburned plants were heavily branched and bore shorter shoots and numerous inflorescences. Unburned plants experienced higher gall frequencies, more galls on their longest shoots, but similar deer browsing compared to burned plants. Ramets with herbivore damage had more branches and inflorescences than undamaged ramets, especially where both herbivores were present. Ceanothus herbaceous{\textquoteright} flexible life history responses suggest tolerance of multiple forms of damage.}, keywords = {LTER-KNZ, fire}, doi = {10.1674/0003-0031(1999)141[0051:EOFBAG]2.0.CO;2}, author = {Throop, H.L. and Fay, P.A.} } @article {KNZ00697, title = {The keystone role of bison in North American tallgrass prairie}, journal = {BioScience}, volume = {49}, year = {1999}, pages = {39 -50}, keywords = {LTER-KNZ}, url = {http://www.jstor.org/stable/10.1525/bisi.1999.49.1.39}, author = {Alan K. Knapp and John M. Blair and J. M. Briggs and Scott. L. Collins and D.C. Hartnett and Johnson, L.C. and Towne, E.G.} } @article {KNZ00717, title = {Relationships between leaf area index and Landsat TM spectral vegetation indices across three temperate zone sites}, journal = {Remote Sensing of the Environment}, volume = {70}, year = {1999}, pages = {52 -68}, abstract = {Mapping and monitoring of leaf area index (LAI) is important for spatially distributed modeling of vegetation productivity, evapotranspiration, and surface energy balance. Global LAI surfaces will be an early product of the MODIS Land Science Team, and the requirements for LAI validation at selected sites have prompted interest in accurate LAI mapping at a more local scale. While spectral vegetation indices (SVIs) derived from satellite remote sensing have been used to map LAI, vegetation type, and related optical properties, and effects of Sun{\textendash}surface{\textendash}sensor geometry, background reflectance, and atmospheric quality can limit the strength and generality of empirical LAI{\textendash}SVI relationships. In the interest of a preliminary assessment of the variability in LAI{\textendash}SVI relationships across vegetation types, we compared Landsat 5 Thematic Mapper imagery from three temperate zone sites with on-site LAI measurements. The sites differed widely in location, vegetation physiognomy (grass, shrubs, hardwood forest, and conifer forest), and topographic complexity. Comparisons were made using three different red and near-infrared-based SVIs (NDVI, SR, SAVI). Several derivations of the SVIs were examined, including those based on raw digital numbers (DN), radiance, top of the atmosphere reflectance, and atmospherically corrected reflectance. For one of the sites, which had extreme topographic complexity, additional corrections were made for Sun{\textendash}surface{\textendash}sensor geometry. Across all sites, a strong general relationship was preserved, with SVIs increasing up to LAI values of 3 to 5. For all but the coniferous forest site, sensitivity of the SVIs was low at LAI values above 5. In coniferous forests, the SVIs decreased at the highest LAI values because of decreasing near-infrared reflectance associated with the complex canopy in these mature to old-growth stands. The cross-site LAI{\textendash}SVI relationships based on atmospherically corrected imagery were stronger than those based on DN, radiance, or top of atmosphere reflectance. Topographic corrections at the conifer site altered the SVIs in some cases but had little effect on the LAI{\textendash}SVI relationships. Significant effects of vegetation properties on SVIs, which were independent of LAI, were evident. The variability between and around the best fit LAI{\textendash}SVI relationships for this dataset suggests that for local accuracy in development of LAI surfaces it will be desirable to stratify by land cover classes (e.g., physiognomic type and successional stage) and to vary the SVI.}, keywords = {LTER-KNZ}, doi = {10.1016/S0034-4257(99)00057-7}, author = {Turner, D.P. and Cohen, W.B. and Kennedy, R.E. and Fassnacht, K.S. and J. M. Briggs} } @inbook {KNZ00661, title = {Belowground biology and processes}, booktitle = {Grassland Dynamics: Long-Term Ecological Research in Tallgrass Prairie}, year = {1998}, pages = {244 -264}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {New York}, keywords = {LTER-KNZ, tallgrass prairie}, author = {C. W. Rice and Todd, T.C. and John M. Blair and Seastedt, T.R. and Ramundo, R.A. and G.T. Wilson}, editor = {Alan K. Knapp and J. M. Briggs and D.C. Hartnett and Scott. L. Collins} } @article {KNZ00637, title = {Biotic interactions between grazers and plants: Relationships contributing to atmospheric boundary layer dynamics}, journal = {Journal of Atmospheric Sciences}, volume = {55}, year = {1998}, pages = {1247 -1259}, abstract = {During 1987 and 1988 First ISLSCP (International Satellite Land Surface Climatology Project) Field Experiment (FIFE) studies conducted in the tallgrass prairie of central Kansas, variations in ungulate grazing intensity produced a patchy spatial and temporal distribution of remaining vegetation. Equally variable plant regrowth patterns contributed further to a broad array of total primary production that resulted in a pronounced mosaic of grazing impacts. This regrowth potential, derived from a relative growth rate (RGR) equation comparing ungrazed and grazed plants, determines much of the ecosystem dynamics within and among the grazed pastures and between years. Rates of change in new plant growth (DRGRg) ranged from 2100\% to 140\%; however, 78\% of the time in 1987 and 71\% in 1988, productivity increased as a function of grazing intensity. Since plant growth potential in ungrazed (RGRug) and grazed systems (RGRg) have inherently different attributes, interactions with the abiotic environment may develop many uncertainties. Thus, changes in growth rates in grazed areas compared to ungrazed areas (DRGRg) may impose major controls over system productivity and associated biological processes currently not accounted for in ecosystem models. Because FIFE microsite atmospheric boundary layer (ABL) studies did not directly incorporate grazing intensity into their design, Type I and Type II statistical errors may introduce significant uncertainties for understanding cause and effect in surface flux dynamics. As a consequence these uncertainties compromise the ability to extrapolate microsite ABL biophysical findings to other spatial and temporal scales.}, keywords = {LTER-KNZ}, url = {http://journals.ametsoc.org/doi/pdf/10.1175/1520-0469(1998)055\%3C1247\%3ABIBGAP\%3E2.0.CO\%3B2}, author = {Dyer, M.I. and Turner, C.L. and Seastedt, T.R.} } @inbook {KNZ00626, title = {A landscape perspective of patterns and processes in tallgrass prairie}, booktitle = {Grassland Dynamics: Long-Term Ecological Research in Tallgrass Prairie}, year = {1998}, pages = {265 -279}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {New York}, keywords = {LTER-KNZ, tallgrass prairie}, author = {J. M. Briggs and Nellis, M.D. and Turner, C.L. and Henebry, G.M. and Su, H.}, editor = {Alan K. Knapp and J. M. Briggs and D.C. Hartnett and Scott. L. Collins} } @inbook {KNZ00651, title = {Patterns and controls of aboveground net primary production in tallgrass prairie}, booktitle = {Grassland Dynamics: Long-Term Ecological Research in Tallgrass Prairie}, year = {1998}, pages = {193 -221}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {New York}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Alan K. Knapp and J. M. Briggs and John M. Blair and Turner, C.L.}, editor = {Alan K. Knapp and J. M. Briggs and D.C. Hartnett and Scott. L. Collins} } @inbook {KNZ00660, title = {Soils and soil biota}, booktitle = {Grassland Dynamics: Long-Term Ecological Research in Tallgrass Prairie}, year = {1998}, pages = {48 -66}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {New York}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Ransom, M.D. and C. W. Rice and Todd, T.C. and Wehmueller, W.A.}, editor = {Alan K. Knapp and J. M. Briggs and D.C. Hartnett and Scott. L. Collins} } @article {KNZ00611, title = {NOAA AVHRR land surface albedo algorithm development}, journal = {International Journal of Remote Sensing}, volume = {18}, year = {1997}, pages = {3761 -3796}, abstract = {The primary objective of this research is to develop a surface albedo model for the National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer (AVHRR). The primary test site is the Konza prairie, Kansas (U.S.A.), used by the International Satellite Land Surface Climatology Project (ISLSCP) in the First ISLSCP Field Experiment (FIFE). In this research, high spectral resolution field spectrometer data was analyzed to simulate AVHRR wavebands and to derive surface albedos. Development of a surface albedo algorithm was completed by analysing a combination of satellite, field spectrometer, and ancillary data. Estimated albedos from the field spectrometer data were compared to reference albedos derived using pyranometer data. Variations from surface anisotropy of reflected solar radiation were found to be the most significant albedo-related error. Additional error or sensitivity came from estimation of a shortwave mid-IR reflectance (1.3-4.0 mum) using the AVHRR red and near-IR bands. Errors caused by the use or AVHRR spectral reflectance to estimate both a total visible (0.4-0.7 pm) and near-IR (0.7-1.3 mum) reflectance were small. The solar spectral integration, using the derived ultraviolet, visible, near-IR and SW mid-IR reflectivities, was not sensitive to many clear-sky changes in atmospheric properties and illumination conditions}, keywords = {LTER-KNZ, ISLSCP}, doi = {10.1080/014311697216612}, author = {Toll, D.L. and Shirley, D. and Kimes, D.S.} } @article {KNZ00612, title = {Soil N and plant responses to fire, topography and supplemental N in tallgrass prairie}, journal = {Ecology}, volume = {78}, year = {1997}, pages = {1832 -1843}, abstract = {Tallgrass prairie in the Flint Hills region of Kansas is characterized by considerable topographic relief coupled with variation in soil properties. These topoedaphic gradients, together with variation in fire regimes, result in temporal and landscape-level variability in soil resource availability and plant responses. Nitrogen usually is considered to be the nutrient most limiting to primary productivity in tallgrass prairie, but few studies have addressed how N availability varies seasonally, or across the landscape and with fire frequency. We measured soil inorganic N, in situ net N mineralization, aboveground net primary productivity (ANPP), and N mass on plots either fertilized with N in 1993 or in 1994, or unfertilized, in uplands and lowlands of two annually burned and two long-term unburned sites during the 1994 growing season. In addition, our study was conducted in the year following record rainfall, allowing us to assess the potential for high precipitation amounts to affect subsequent N cycling and plant production. Both fire treatment and topography affected soil N availability. In general, N mineralization was greater on unburned than on burned sites and was up to five times greater on uplands than lowlands. Total extractable soil N was highest early in the season and least at midseason, and it also tended to be higher in unburned sites than burned sites on unfertilized plots. Added N increased ANPP, but there were no differences between plots fertilized in 1994 and those fertilized in 1993. In general, patterns of ANPP on control plots were consistent with known production responses to topography and burning (higher in annually burned sites and in lowland sites) but were inversely related or unrelated to patterns of N availability (higher in unburned sites and at upland topographic positions). Potential loss of N by volatilization during spring burning was greater than in years with normal rainfall amounts and represented a significant portion of aboveground plant N mass. Potential N losses did not appear to limit ANPP or N availability in the current growing season. Our results suggest that different factors control soil N mineralization and plant productivity, which explains, in part, why patterns of ANPP are not well correlated with patterns of N availability in tallgrass prairie ecosystems.}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1890/0012-9658(1997)078[1832:SNAPRT]2.0.CO;2}, author = {Turner, C.L. and John M. Blair and Schartz, R.J. and Neel, J.C.} } @article {KNZ00581, title = {Spatial and temporal patterns of vegetation in the Flint Hills}, journal = {Transactions Kansas Academy of Science}, volume = {100}, year = {1997}, pages = {10 -20}, abstract = {In tallgrass prairie, complex interactions among multiple limiting resources in combination with a variety of land use practices can lead to a heterogeneous landscape. Remote-sensing data (AVHRR) were coupled with abiotic factors to explore spatial and temporal vegetation patterns of the Flint Hills in Kansas and Oklahoma. This information should enable the detection of both natural (e.g., interannual variation in precipitation and temperature) and anthropogenic (e.g., climate change, over-grazing, land-use practices) stresses on this grassland ecosystem. Shifts in the spatial and temporal patterns of vegetation (as measured from NDVI by AVHRR) have been correlated with meteorological data (from 117 weather stations) to identify key abiotic variables that determined vegetation patterns across this region. In 4 years, the combination of annual precipitation and growing degree days was useful to detect spatial and temporal vegetation patterns of the Flint Hills. However, it is imperative that land-use patterns are known in order to assess adequately spatial and temporal patterns of vegetation in this area.}, keywords = {LTER-KNZ}, doi = {10.2307/3628435}, author = {J. M. Briggs and Rieck, D.R. and Turner, C.L. and Henebry, G.M. and Goodin, D.G. and Nellis, M.D.} } @article {KNZ00573, title = {Biomass and density responses in tallgrass prairie legumes to annual fire and topographic position}, journal = {American Journal of Botany}, volume = {83}, year = {1996}, pages = {175 -179}, abstract = {Annually burned tallgrass prairie is purported to be a nitrogen-limited system, especially when compared to unburned prairie. To test the hypothesis that legumes, potential nitrogen-fixers, would increase in relative abundance in annually burned sites, we assessed their density and biomass for two seasons on upland and lowland soils in annually burned and unburned watersheds. Total legume density was significantly higher in burned (8.0 {\textpm} 1.0 [SE] stems/m2) than in unburned watersheds (3.0 {\textpm} 0.3 stems/m2). Species with higher (P < 0.05) densities in burned than in unburned prairie included Amorpha canescens, Dalea candida, Dalea purpurea, Lespedeza violacea, Psoralea tenuiflora, and Schrankia nuttallii. Desmodium illinoense was the only legume that responded negatively to annual fire. Total legume biomass did not differ between burned (11.3 {\textpm} 1.3 g/m2) and unburned prairie (10.5 {\textpm} 0.9 g/m2). Biomass productions of Dalea candida and Psoralea tenuiflora were higher (P < 0.05) in burned than in unburned sites, but biomasses of other legumes were similar between burn treatments. Average individual stem masses of Amorpha canescens and Baptisia bracteata were significantly greater in unburned than in burned prairie. Legumes were affected differentially by topographic location. Total legume density was higher (P < 0.05) on lowland soils (6.6 {\textpm} 1.0 stems/m2) than on upland soils (4.3 {\textpm} 0.5 stems/m2). However, total legume biomass was not different between lowland soils (12.0 {\textpm} 1.2 g/m2) and upland soils (9.9 {\textpm} 1.0 g/m2). Densities and biomasses of Amorpha canescens, Desmodium illinoense, and Lespedeza capitata were higher on lowland sites than on upland sites, whereas densities and biomasses of Baptisia bracteata and Dalea purpurea were higher on upland than on lowland soils. Most legume species are either fire tolerant or exhibit a positive response to fire and their persistence in annually burned prairie suggests that they may play an important role in the nitrogen budget of this ecosystem.}, keywords = {LTER-KNZ, tallgrass prairie}, url = {http://www.jstor.org/stable/2445935}, author = {Towne, E.G. and Alan K. Knapp} } @article {KNZ00572, title = {Effects of management practices on nematode community structure in tallgrass prairie}, journal = {Applied Soil Ecology}, volume = {3}, year = {1996}, pages = {235 -246}, abstract = {The effects of burning, mowing, and nitrogen (N) and phosphorus (P) fertilization on the trophic structure of a tallgrass prairie nematode community were examined in a long-term field experiment established in 1986. Nematode densities and trophic composition were determined in October of 1987, 1989, and 1994 following 2, 4, and 9 years of treatment, respectively. Total populations of obligate herbivores tended to increase with annual burning and N fertilization but responses by individual taxa were relative to the structure and composition of vegetation as determined by management practice. In contrast, mowing resulted in consistent reductions in herbivore densities. The family Tylenchidae, with species classified as both root and fungal feeders, exhibited short-term decreases in numbers due to burning and long-term increases in numbers due to mowing. Treatment responses by this group were more consistent with the behavior of known fungal-feeding than root-feeding nematodes. Microbivore densities increased with burning and N fertilization, while numbers of omnivores and predators declined with chronic N additions. The effects of P fertilization on nematode population densities varied with management practice, primarily N fertilization. Canonical discriminant analysis differentiated trophic groups based on their responses to mowing and P-fertilization. Measurements of the trophic composition of the nematode community, particularly the relative abundance of individual herbivore taxa and the proportion of fungivores to microbivores, were good indicators of ecosystem responses to management practices.}, keywords = {LTER-KNZ, disturbance, fire, Mowing, Nematode, nitrogen, tallgrass prairie, Trophic structure}, doi = {10.1016/0929-1393(95)00088-7}, author = {Todd, T.C.} } @article {KNZ00571, title = {Elucidation of factors associated with the maturity related decline in degradability of big bluestem cell wall}, journal = {Journal of Animal Science}, volume = {74}, year = {1996}, pages = {648 -657}, abstract = {Big bluestem (Andropogon gerardii) forage samples were collected from three ungrazed, annually burned pastures at 38, 58, and 97 d after burning. Cell wall material received five treatments: chlorite delignification, chlorite delignification plus alkali extraction, NaOH, NaOCH3 in methanol, or NaBH4. Untreated and treated cell walls were analyzed for carbohydrate composition (glucose, xylose, arabinose, galactose, and uronic acids), acetyl bromide lignin, acid detergent lignin, alkali-labile phenolics (p-coumaric and ferulic acids), acetyl groups, and 24- and 72-h in vitro degradabilities of neutral monosaccharides. A number of compositional features, notably concentrations of xylose, core lignin as measured by acetyl bromide lignin, alkali-labile phenolics, and acetyl groups, were well related to the decline in cell wall degradability that occurred with increasing maturity of big bluestem. p-Coumaric acid increased with increasing maturity to a greater extent than did ferulic acid. Acid detergent lignin was not well related to degradability of the cell wall for either the untreated or chemically treated cell walls. Chemical treatments failed to identify any particular cell wall component as being most inhibitory. However, all treatments improved in vitro degradability of the carbohydrate fraction, indicating that components contributing to the undegradability of big bluestem cell wall are sensitive to chemical alteration. Treatments involving alkali were most effective for improving degradability of big bluestem cell walls.}, keywords = {LTER-KNZ}, url = {https://dl.sciencesocieties.org/publications/jas/abstracts/74/3/648}, author = {Titgemeyer, E.C. and Cochran, R.C. and Towne, E.G. and Armendariz, C.K. and K.C. Olson} } @article {KNZ00533, title = {Nitrogen transport from tallgrass prairie watersheds}, journal = {Journal of Environmental Quality}, volume = {25}, year = {1996}, pages = {973 -981}, abstract = {Discharge and N content of surface water flowing from four Karst watersheds on Konza Prairie Research Natural Area, Kansas, managed with different burn frequencies, were monitored from 1986 to 1992. The goal was to establish the influence of natural processes (climate, fire, and bison grazing) on N transport and concentration in streams. Streams were characterized by variable flow, under conditions that included an extreme flood and a drought during which all channels were dry for over a year. The estimated groundwater/stream water discharge ratio varied between 0.15 to 6.41. Annual N transport by streams, averaged across all watersheds and years, was 0.16 kg N ha-1 yr-1. Annual N transport per unit area also increased as the watershed area increased and as precipitation increased. Total annual transport of N from the prairie via streams ranged from 0.01 to 6.0\% of the N input from precipitation. Nitrate and total N concentrations in surface water decreased (P < 0.001, r values ranged from 0.14{\textendash}0.26) as length of time since last fire increased. Increased watershed area was correlated negatively (P < 0.0001) to stream water concentrations of NO-3N and total N (r values = -0.43 and -0.20, respectively). Low N concentration is typical of these streams, with NH+4-N concentrations below 1.0 {\textmu}g L-1, NO-3-N ranging from below 1.4 to 392 {\textmu}g L-1, and total N from 3.0 to 714 {\textmu}g L-1. These data provide an important baseline for evaluating N transport and stream water quality from unfertilized grasslands.}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.2134/jeq1996.00472425002500050007x}, author = {W. K. Dodds and John M. Blair and Henebry, G.M. and Koelliker, J.K. and Ramundo, R.A. and Tate, C.M.} } @article {KNZ00574, title = {Responses of a C4 grass and three C3 forbs to variation in nitrogen and light in tallgrass prairie}, journal = {Ecology}, volume = {77}, year = {1996}, pages = {1738 -1749}, abstract = {In tallgrass prairie, high plant species diversity results not from a large number of grass species, but from a large number of forb (nongrass, herbaceous) species. Forbs exhibit morphological, life history, and ecophysiological characteristics that contrast sharply with those of the dominant C4 grasses. Success of the subdominant forbs varies strongly with topographic position and burning regime, and landscape scale patterns of abundance are well documented. But comparatively little is known about the mechanisms determining these patterns in persistent tallgrass prairie forbs. To elucidate these mechanisms, (1) leaf{\textemdash}level physiological characteristics of the dominant C4 grass, Andropogon gerardii, and four co{\textemdash}occurring C3 forbs were measured in response to natural and experimentally manipulated gradients of N availability, and (2) seasonal light environments of forbs in contrasting topographic positions and burning regimes and their morphological and physiological responses in these environments were compared to determine whether resource availability and utilization patterns contributed to patterns of forb distribution and abundance. The effects of burning regime and topographic position on maximum rate of photosynthesis (A) and stomatal conductance to water vapor (g) measured at the leaf level were not consistent with patterns of forb abundance. Nitrogen did not appear to limit forb physiological processes, even though increased N availability resulted in higher tissue N concentrations and greater biomass. There was no consistent increase in (A) or decrease in (g) in response to fertilization. However, (A) at low light levels was as much as 67\% higher in fertilized Vernonia baldwinii and A. gerardii compared to unfertilized plants. Greater light availability to forbs in the canopy was associated with lower grass biomass production in uplands compared to lowlands and in unburned compared to burned sites. Forbs did not appear to adjust morphologically (leaf area and plant height) to different light environments at different sites. As a result, as much as 90\% of forb leaf area in the burned lowland was displayed in low light, whereas as little as 30\% of forb leaf area was in low light in the uplands at midseason. Estimates of potential whole{\textemdash}plant carbon uptake, based on leaf area distribution relative to available light and (A) as a function of light availability, agreed well with patterns of forb abundance and production. Differences in light availability may account for much of the variability in forb abundance related to burning regime and topographic position by limiting carbon gain in forbs more in burned lowlands than in other sites.}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.2307/2265779}, author = {Turner, C.T. and Alan K. Knapp} } @article {KNZ00523, title = {Comparative gas exchange and nitrogen responses of the dominant C4 grass, Andropogon gerardii, and five C3 forbs to fire and topographic position in tallgrass prairie during a wet year}, journal = {International Journal of Plant Science}, volume = {156}, year = {1995}, pages = {216 -226}, abstract = {High plant species diversity in tallgrass prairie results not from a large number of grass species but, rather, from a large number of forb (nongrass, herbaceous) species. Although morphological characteristics of tallgrass prairie forbs differ strongly from those of the grasses and their patterns of abundance vary substantially with burning regime and topographic position, comparatively little is known about the ecology of persistent tallgrass prairie forbs. We measured leaf-level physiological characteristics of the dominant C4 grass, Andropogon gerardii, and five co-occurring C3 forb species in response to burning regime and topographic position to determine if there were either absolute or seasonal differences in resource utilization patterns that could contribute to the patterns of forb distribution and abundance in tallgrass prairie. In a wet year, neither fire nor topographic position affected leaf-level physiological characteristics in the grass and forbs studied, and thus responses were not consistent with extant patterns of forb abundance (greater forb abundance in unburned and upland sites). Water use efficiency in A. gerardii was 40\%-170\% greater and foliar N concentration was consistently lower in the grass than in the forbs, but there were no distinct or consistent differences between the grass and forbs in maximum rates of photosynthesis and stomatal conductance or xylem pressure potential. Moreover, seasonal patterns of gas exchange in forbs and the grass were not different, as might be expected when comparing C3 and C4 species. These results indicate that, when assessed at the leaf level, responses of these prairie plants to fire or topographic position during a wet year are not indicative of their success in these sites. However, seasonal water stress is a typical feature of the tallgrass prairie environment and water use patterns indicate that the prevalence of soil moisture limitations in most years may be a key factor influencing plant distribution and success in this ecosystem.}, keywords = {LTER-KNZ, tallgrass prairie}, url = {http://www.jstor.org/stable/2474960}, author = {Turner, C.T. and Kneisler, J.R. and Alan K. Knapp} } @proceedings {KNZ00487, title = {Dynamics of big bluestem (Andropogon gerardii) in ungrazed tallgrass prairie}, year = {1995}, pages = {9 -15}, keywords = {LTER-KNZ}, author = {D.J. Gibson and Towne, E.G.}, editor = {D.C. Hartnett} } @article {KNZ00522, title = {Elemental analysis of mineral lick soils from the Serengeti National Park, the Konza Prairie and Yellowstone National Park}, journal = {Ecography}, volume = {18}, year = {1995}, pages = {91 -94}, abstract = {We analyzed mineral lick soils and non-mineral lick soils from the Serengeti National Park, the Konza Prairie, and Yellowstone National Park. The concentrations of 14 different elements considered important for ungulate nutrition were analyzed to determine the relative importance of Na vs other elements in attracting animals to lick areas. Only Na was consistently higher in the mineral lick soils of the three ecosystems. Mean Na concentrations were c. 20{\texttimes} greater in Serengeti licks, 10{\texttimes} greater in Konza licks and 3{\texttimes} greater in Yellowstone licks compared to the respective non-lick soils. Despite the numerous elements analyzed for this survey, our results suggest that Na is the primary element initiates mineral lick use in these widely separated ecosystems. The widespread distribution of Na-deficient forage likely explains the importance of Na in most mineral licks.}, keywords = {LTER-KNZ}, url = {http://www.jstor.org/stable/3683223}, author = {Tracy, B.F. and McNaugthon, S.J.} } @proceedings {KNZ00521, title = {Influence of fire frequency and burning date on the proportion of reproductive tillers in big bluestem and indiangrass}, year = {1995}, pages = {75 -78}, keywords = {LTER-KNZ, fire}, url = {http://images.library.wisc.edu/EcoNatRes/EFacs/NAPC/NAPC14/reference/econatres.napc14.etowne.pdf}, author = {Towne, E.G.}, editor = {D.C. Hartnett} } @article {KNZ00489, title = {Plant productivity and nitrogen gas fluxes in tallgrass prairie}, journal = {Landscape Ecology}, volume = {10}, year = {1995}, pages = {255 -266}, abstract = {We explored relationships between plant productivity and annual fluxes of nitrogen (N2) and nitrous oxide (N2O) in a tallgrass prairie landscape in central Kansas. Our objective was to develop predictive relationships between these variables that could be used in conjunction with remote sensing information on plant productivity to produce large-area estimates of N gas fluxes. Our hypothesis was that there are inherent relationships between plant productivity and N gas fluxes in tallgrass prairie because both are controlled by water and N availability. The research was carried out as part of a multi-investigator project, the First ISLSCP Field Experiment (FIFE, ISLSCP = International Satellite Land Surface Climatology Program), directed toward the use of remote sensing to characterize land-atmosphere interactions. Fluxes of N2 (denitrification) and N2O were measured using soil core techniques. Estimates of annual flux were produced by temporal extrapolation of measured rates. Annual aboveground net primary productivity (ANPP) was estimated from measurements of the maximum standing crop of plant biomass. There were strong relationships between ANPP and N gas fluxes, and between a satellite remote sensing-based index of plant productivity (normalized difference vegetation index, NDVI) and gas fluxes. We used these relationships to convert images of NDVI into images of N gas fluxes for one 83 ha watershed and for the entire 15 by 15 km FIFE site. These images were used to compute mean landscape gas fluxes (0.62 g N m-2 y-1 for N2, 0.66 g N m-2 y-1 for N2O) and total N gas production for the two areas. Our flux and production values are useful for comparison with values produced by simulation models and site-specific studies, and for assessing the significance of N gas production to ecosystem and landscape scale processes related to nutrient cycling, water quality and atmospheric chemistry. }, keywords = {LTER-KNZ, denitrification, NDVI, nitrous oxide, remote sensing}, doi = {10.1007/BF00128993}, author = {Groffman, P.M. and Turner, C.L.} } @mastersthesis {KNZ00470, title = {Characterizing herbivore resistance traits in eight tallgrass prairie grasses}, volume = {MS Thesis}, year = {1994}, pages = {1 -63}, school = {Kansas State University}, type = {M.S. Thesis}, address = {Manhattan, KS}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Thomas, M.A.} } @article {KNZ00472, title = {Plant production and the biomass of soil microorganisms in late-successional ecosystems: A continental-scale study}, journal = {Ecology}, volume = {75}, year = {1994}, pages = {2333 -2347}, abstract = {Annual C inputs from plant production in terrestrial ecosystems only meet the maintenance energy requirements of soil microorganisms, allowing for little or no net annual increase in their biomass. Because microbial growth within soil is limited by C availability, we reasoned that plant production should, in part, control the biomass of soil microorganisms. We also reasoned that soil texture should further modify the influence of plant production on soil C availability because fine-textured soils typically support more microbial biomass than coarse-textured soils. To test these ideas, we quantified the relationship between aboveground net primary production (ANPP) and soil microbial biomass in late-successional ecosystems distributed along a continent-wide gradient in North America. We also measured labile pools of C and N within the soil because they represent potential substrate for microbial activity. Ecosystems ranged from a Douglas-fir forest in the western United States to the grasslands of the mid-continent to the hardwood forest in the eastern U.S. Estimates of ANPP obtained from the literature ranged from 82 to 1460 g@?m^-^2@?yr^-^1. Microbial biomass C and N were estimated by the fumigation-incubation technique. Labile soil pools of C and N and first-order rate constants for microbial respiration and net N mineralization were estimated using a long-term (32 wk) laboratory incubation. Regression analyses were used to relate ANPP and soil texture with microbial biomass and labile soil C and N pools. Microbial biomass carbon ranged from 2 g/m^2 in the desert grassland to 134 g/m^2 in the tallgrass prairie; microbial N displayed a similar trend among ecosystems. Labile C pools, derived from a first-order rate equation, ranged from 115 g/m^2 in the desert grassland to 491 g/m^2 in the southern hardwood forest. First-order rate constants for microbial respiration (k) fell within a narrow range of values (0.180 to 0.357 wk^-^1), suggesting that labile C pools were chemically similar among this diverse set of ecosystems. Potential net N mineralization rates over the 32-wk incubation were linear in most ecosystems with first-order responses only in the alpine tundra, tallgrass prairie, and forests. Microbial biomass C displayed a positive, linear relationship with ANPP (r^2 = 0.51), but was not significantly related to soil texture. Labile C also was linearly related to ANPP (r^2 = 0.32) and to soil texture (r^2 = 0.33). Results indicate that microbial biomass and labile organic matter pools change predictably across broad gradients of ANPP, supporting the idea that microbial growth in soil is constrained by C availability.}, keywords = {LTER-KNZ}, doi = {10.2307/1940888}, author = {Zak, D.R. and Tilman, D. and Parameter, R.R. and Fisher, F.M. and C. W. Rice and Vose, J. and Milchunas, D. and Martin, C.W.} } @article {KNZ00403, title = {Denitrification in a tallgrass prairie landscape}, journal = {Ecology}, volume = {74}, year = {1993}, pages = {855 -862}, abstract = {We characterized factors controlling denitrification and quantified rates of N gas production by this process in a tallgrass prairie landscape in central Kansas. The experimental design included three land use classes (unburned, annually burned, and annually burned and grazed) in factorial combination with three slope positions (summit, back{\textemdash}slope, toe{\textemdash}slope), plus a cultivated site in a toe{\textemdash}slope position (10 sites total). Denitrification was measured using an acetylene{\textemdash}based soil core technique four times in 1987, once in early 1988, and six times in 1989. Cores were incubated under field{\textemdash}moist conditions and after amendment with water or water plus nitrate. Microbial biomass and nitrification and dentrification enzyme activities were also measured. Denitrification was higher (P < .05) in unburned sites than in burned, and grazed, and cultivated sites in both 1987/1988 and 1989. The cultivated site consistently had low rates of denitrification relative to the native prairie sites, even when water and nitrate were added. Levels of microbial biomass C and nitrification and denitrification enzyme activities were an order of magnitude lower in the cultivated site than in the native prairie sites. Denitrification rates were highest in the early spring of 1987 and were low at all other times. Although temporal patterns of activity were generally related to patterns of soil moisture, water additions did not stimulate activity in ungrazed prairie soils. Water plus nitrate additions consistently gave significant increases in activity. The results are consistent with previous research that has found that unburned prairie is wetter and has higher concentrations of NO3{\textemdash} in soil solution than burned sites. In certain years, denitrification may be significant to site fertility, landscape water quality, and atmospheric chemistry in the tallgrass prairie region.}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.2307/1940811}, author = {Groffman, P.M. and C. W. Rice and Tiedje, J.M.} } @article {KNZ00394, title = {Herbivory and its consequences}, journal = {Ecological Applications}, volume = {3}, year = {1993}, pages = {10 -16}, abstract = {We argue that herbivores often induce nonlinear or biphasic growth and development in plants. Collectively these individual responses translate into a system{\textemdash}level optimization curve wherein at low levels of herbivory overall community responses show increases in production potential, whereas extreme herbivory causes extreme reduction in productivity. The transition between these two states defines a point of optimal herbivory in respect to C and N processes.We present four case examples from the literature demonstrating such nonlinear responses, suggesting a widespread existence for this herbivore{\textemdash}plant phenomenon. The nonlinear responses appear to demonstrate temporal and spatial scale dependencies.}, keywords = {LTER-KNZ}, doi = {10.2307/1941781}, author = {Dyer, M.I. and Turner, C.L. and Seastedt, T.R.} } @article {KNZ00429, title = {Maximization of aboveground grassland production: the role of defoliation frequency, intensity and history}, journal = {Ecological Applications}, volume = {3}, year = {1993}, pages = {175 -186}, abstract = {Production of tallgrass prairie vegetation was measured on experimental plots in which defoliation intensity and frequency were manipulated by mowing and using movable exclosures on areas chronically grazed by cattle. Defoliation history largely controlled whether or not defoliated plants overcompensated (exhibited enhanced production compared to undefoliated controls) for tissue removal. Plants on chronically grazed sites only compensated for foliage removed by grazers. Production on plots mowed prior to the year of measurement was similar to that on chronically grazed sites, while previously unmowed plots exhibited substantial aboveground overcompensation. Aboveground production was maximized by the most frequent mowing treatment and by intermediate mowing heights. Nitrogen and phosphorus concentrations and amounts in aboveground tissues were increased by mowing and grazing. Current mowing regime was more important than mowing history in determining nitrogen concentrations except very early in the growing season. Effects of grazing and mowing on belowground biomass were inconsistent, but frequent mowing appeared to limit accumulation of belowground N reserves and biomass. In North American grasslands, overcompensation is a nonequilibrium plant response to grazing. Photosynthate that would be stored as reserves and used for root growth and flower and seed production instead is used to replace lost leaf area, thereby resulting in higher foliage productivity. However, under chronic grazing or mowing, vegetation is prevented from maintaining high nutrient and water uptake capacity (large root biomass) and accumulating reserves that allow overcompensation responses.}, keywords = {LTER-KNZ}, doi = {10.2307/1941800}, author = {Turner, C.L. and Seastedt, T.R. and Dyer, M.I.} } @article {KNZ00428, title = {Methane consumption and carbon dioxide emission in tallgrass prairie: effects of biomass burning and conversion to agriculture}, journal = {Global Biogeochemical Cycles}, volume = {7}, year = {1993}, pages = {735 -784}, abstract = {Consumption of atmospheric methane and emission of carbon dioxide by soils were measured on unburned and annually burned tallgrass prairie and on adjacent wheat and sorghum agricultural plots in Kansas. Profiles of CH4 and CO2 concentration with soil depth were also measured. Overall patterns of CH4 consumption by soils varied temporally, with soil depth and land use. Mean CH4 consumption for the 200-day sampling period was -1.02 mg CH4 m-2 d-1 (SE=0.13, n=41) for burned prairie, -0.63 (SE=0.09, n=45) for unburned prairie, -0.85 (SE=0.20, n=36) for wheat, and -0.45 (SE=0.08, n=40) for sorghum. Less than 20 \% of the variance in CH4 consumption was explained by soil temperature and/or moisture content. Overall patterns of CO2 emission from prairie and agricultural soils varied temporally, but not among land use. Mean CO2 emission for the 200-day sampling period was 15.7 g CO2 m-2 d-1 (SE=1.8, n=41) for burned prairie, 14.5 (SE=1.3, n=45) for unburned prairie, 13.9 (SE=2.1, n=36) for wheat, and 10.3 (SE=2.1, n=40) for sorghum. More than 70\% of the variance in prairie CO2 emission rate was explained by soil temperature and moisture. Crop management practices influenced the timing of CO2 emission from agricultural plots but not the net annual rate of emission. Methane concentrations generally decreased and CO2 concentrations increased with soil depth, and the magnitude of CH4 and CO2 flux generally increased with increased magnitude of the soil gas concentration gradient. Fertilization of agricultural fields had no measured effect on CH4 or CO2 flux or on soil gas concentrations.}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1029/93GB02560}, author = {Tate, C.M. and Strigel, R.G.} } @article {KNZ00395, title = {Microbial decomposition of elm and oak leaves in a karst aquifer}, journal = {Applied Environmental Microbiology}, volume = {59}, year = {1993}, pages = {3592 -3596}, abstract = {Dry Chinquapin oak (Quercus macrocarpa) and American elm (Ulmus americana) leaves were placed in four microcosms fed by groundwater springs to monitor changes in dry mass, ash-free dry mass, and microbial activity over a 35-day period. Oxygen microelectrodes were used to measure microbial activity and to estimate millimeter-scale heterogeneity in that activity. Oak leaves lost mass more slowly than elm leaves. Generally, there was a decrease in total dry weight over the first 14 days, after which total dry weight began to increase. However, there were consistent decreases in ash-free dry mass over the entire incubation period, suggesting that the material remaining after initial leaf decomposition trapped inorganic particles. Microbial activity was higher on elm leaves than on oak leaves, with peak activity occurring at 6 and 27 days, respectively. The level of oxygen saturation on the bottom surface of an elm leaf ranged between 0 and 75\% within a 30-mm2 area. This spatial heterogeneity in O2 saturation disappeared when the water velocity increased from 0 to 6 cm s-1. Our results suggest that as leaves enter the groundwater, they decompose and provide substrate for microorganisms. The rate of decomposition depends on leaf type, small-scale variations in microbial activity, water velocity, and the length of submersion time. During the initial stages of decomposition, anoxic microzones are formed that could potentially be important to the biogeochemistry of the otherwise oxic aquifer.}, keywords = {LTER-KNZ}, url = {http://aem.asm.org/content/59/11/3592.short}, author = {Eichem, A. and W. K. Dodds and Tate, C.M. and Edler, C.} } @book {KNZ00416, title = {Stream Research in the LTER Network}, year = {1993}, pages = {114 -}, publisher = {LTER Network LTER publication no. 15}, organization = {LTER Network LTER publication no. 15}, address = {Seattle, WA}, keywords = {LTER-KNZ}, author = {Meyer, J.L. and Crocker, T. and D{\textquoteright}Angelo, D. and W. K. Dodds and Findlay, S.E.G. and Oswood, M. and Repert, D. and Toetz, D.} } @article {KNZ00383, title = {Effects of management and topography on the radiometric response of a tallgrass prairie}, journal = {Journal of Geophysical Research}, volume = {97}, year = {1992}, pages = {18855 -18666}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1029/92JD00654}, author = {Turner, C.L. and Seastedt, T.R. and Dyer, M.I. and Kittel, T.G.F. and Schimel, D.S.} } @proceedings {KNZ00375, title = {Effects of tallgrass prairie vegetation on the concentration and seasonality of nitrate\-nitrogen in soil water and streams}, year = {1992}, pages = {9 -12}, publisher = {University of Northern Iowa}, abstract = {

Inorganic nitrogen concentrations in tallgrass prairie soils and streams exhibit a sinusoidal seasonal pattern; nitrate levels are relatively high in winter and low in summer. The pattern is not observed in either rainfall or canopy drip (throughfall). Thus, the pattern is created by plant root-microbial interactions; when roots are not active, nitrates accumulate and can be leached from the soil. We used nitrogen fertilizer and herbicide in a factorial experiment to test the strength of root uptake activities on soil water nitrogen. Soil-water nitrate concentrations were 10 times higher when prairie roots were deactivated by application of a foliar herbicide. Ammonium nitrogen concentrations were unaffected. When fertilizer was added, nitrate levels of soil water beneath herbicide-treated vegetation were double that of untreated prairie. Mineralization of nitragen from herbicide-treated roots was not believed to be the source of the increased nitrate. These and previous studies at Konza Prairie emphasize the importance of plant cover in maintaining low nitrate concentrations of streams

}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Ramundo, R.A. and Tate, C.M. and Seastedt, T.R.}, editor = {Smith, D.A. and Jacobs, C.A.} } @article {KNZ00360, title = {Relationships of mycorrhizal symbiosis, rooting strategy and phenology among tallgrass prairie forbs}, journal = {Canadian Journal of Botany}, volume = {70}, year = {1992}, pages = {1521 -1528}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1139/b92-191}, author = {Hetrick, B.A.D. and G.T. Wilson and Todd, T.C.} } @article {KNZ00382, title = {Soil invertebrate and plant responses to mowing and Carbofuran application in a North American tallgrass prairie}, journal = {Plant and Soil}, volume = {144}, year = {1992}, pages = {117 -124}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1007/BF00018852}, author = {Todd, T.C. and James, S.W. and Seastedt, T.R.} } @article {KNZ00341, title = {Cryptosporidium and Giardia in surface waters in and around Manhattan, Kansas}, journal = {Transaction of the Kansas Academy of Science}, volume = {94}, year = {1991}, pages = {101 -106}, abstract = {

Cryptosporidium spp. and Giardia spp. are intestinal parasites that can be transmitted through water contaminated by feces. Over a 16 month period, surface waters were examined in Kansas in order to measure local geographic distribution and seasonal fluctuation of oocyst and cyst populations. Cryptosporidium and/or Giardia were found in 86 percent of the locations surveyed

}, keywords = {LTER-KNZ}, doi = {10.2307/3627857}, author = {Todd, C.S. and Phillips, M.S. and Marchin, G.L. and Upton, S.J.} } @inbook {KNZ00331, title = {Image textural measures as indices of landscape patterns}, booktitle = {Quantitative Methods in Landscape Ecology: The Analysis and Interpretation of Landscape Heterogeneity}, year = {1991}, pages = {77 -103}, publisher = {SpringerVerlag}, organization = {SpringerVerlag}, address = {New York, NY}, keywords = {LTER-KNZ}, author = {Musick, B.H. and Grover, H.D.}, editor = {Turner, M.G. and Gardner, R.H.} } @inbook {KNZ00340, title = {Improving use of existing data}, booktitle = {Comparative Analyses of Ecosystems: Patterns, Mechanisms and Theories}, year = {1991}, pages = {348 -350}, publisher = {SpringerVerlag}, organization = {SpringerVerlag}, keywords = {LTER-KNZ}, author = {Tate, C.M. and Jones, C.G.}, editor = {Cole, J.J. and Findlay, S.E.G. and Lovett, G.M.} } @article {KNZ00313, title = {Influence of mowing and fertilization on biomass, productivity and spectral reflectance in Bromus inermis plots}, journal = {Ecological Applications}, volume = {1}, year = {1991}, pages = {443 -452}, keywords = {LTER-KNZ}, doi = {10.2307/1941901}, author = {Dyer, M.I. and Turner, C.L. and Seastedt, T.R.} } @article {KNZ00314, title = {Remote sensing measurements of production processes in grazing lands: the need for new methodologies}, journal = {Agriculture, Ecosystems and Environment}, volume = {34}, year = {1991}, pages = {495 -505}, abstract = {

Remote sensing of grazinglands to obtain estimates of productivity relies entirely upon absorption and reflectance properties of the vegetation and its background to provide accurate qualitative and quantitative values. Interpretations of these signals are highly dependent on vegetation responses to perturbations, such as grazing or alterations in nutrient cycles. If remote sensing models of grassland growth ignore feedbacks derived from grazing animals, or only negative feedbacks are assumed, there is a likelihood of errors developing during model validation. We review fundamental assumptions made when using remote sensing data from grazing systems and give examples of the problems involved

}, keywords = {LTER-KNZ}, doi = {10.1016/0167-8809(91)90132-H}, author = {Dyer, M.I. and Turner, C.L. and Seastedt, T.R.} } @article {KNZ00332, title = {Stochastic analysis of the dynamics of nitrogen concentration in a stream ecosystem}, journal = {Ecological Modeling}, volume = {56}, year = {1991}, pages = {33 -45}, keywords = {LTER-KNZ}, doi = {10.1016/0304-3800(91)90191-3}, author = {Nassar, R. and Stewart, R. and Tate, C.M.} } @article {KNZ00283, title = {Differential responses of C3 and C4 grasses to mycorrhizal symbiosis, phosphorus fertilization, and soil microorganisms}, journal = {Canadian Journal of Botany}, volume = {68}, year = {1990}, pages = {461 -467}, abstract = {

The responses of five C4, warm-season and five C3, cool-season tallgrass prairie grasses to phosphorus (P) fertilization, mycorrhizae, and soil microorganisms were compared in greenhouse studies. The warm-season grasses responded positively to mycorrhizae and to P fertilization, but mycorrhizal plants did not respond to P. The soil microflora reduced mycorrhizal plant dry weight and root colonization. In contrast, cool-season grasses did not respond to mycorrhizae or P fertilization. Soil microorganisms did not suppress cool-season plant growth, but root colonization was reduced in nonsterile soil. For the warm-season grasses there was an inverse relationship between mycorrhizal root colonization and P fertilization and a positive relationship between root colonization and plant dry weight. For the cool-season grasses there was also an inverse relationship between root colonization and P fertilization, but the relationship between root colonization and plant dry weight was negative. In both the warm-season and cool-season grasses, low levels of mycorrhizal root colonization persisted even when P fertilization was sufficient to eliminate mycorrhizal effects on plant growth. Thus, warm-and cool-season grasses display profoundly different strategies for nutrient acquisition. Key words: cool-season grasses, warm-season grasses, vesicular-arbuscular mycorrhizae

}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1139/b90-061}, author = {Hetrick, B.A.D. and G.T. Wilson and Todd, T.C.} } @phdthesis {KNZ00299, title = {Effects of grazing on primary production and surface climatological variables in tallgrass prairie}, volume = {PhD Dissertation}, year = {1990}, pages = {1 -105}, school = {Kansas State University}, type = {Ph.D. Thesis}, address = {Manhattan, KS}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Turner, C.L.} } @article {KNZ00298, title = {Patterns and controls of nitrogen in tallgrass prairie streams}, journal = {Ecology}, volume = {71}, year = {1990}, pages = {2007 -2018}, abstract = {

A descriptive and experimental approach was used to study patterns of nitrogen concentrations in tallgrass prairie streams in Kansas. Nitrate concentrations varied depending on the year, season, time of day, stream flow conditions, source of water, and location where the sample was taken. Mean nitrate concentrations during the dormant season decreased from 1982 to 1984, corresponding to above normal precipitation during this same period. Nitrate concentrations decreased from third-order (grass/shrub riparian vegetation) to fourth-order channels (gallery forests). Nitrate, organic N, and total N were higher in a third-order intermittent stream than in a third-order perennial stream. Water from seeps and tributaries had higher nitrate concentrations than stream water; however, streams and tributaries had higher organic N than seeps. Maximum nitrate concentrations during storm flows were directly related to the magnitude of storms and inversely related to the frequency of storm events. The activity of terrestrial vegetation influenced nitrate concentrations within streams, seeps, and tributaries; nitrate concentrations were always higher during periods of vegetation dormancy. Aquatic biota influenced both spatial patterns (downstream decrease in nitrate concentrations and increase in organic N) and diel patterns of nitrate concentration (night greater than day). Uptake rates of nitrate by biota were greater during the day than during the night as determined by experimental addition of nitrate. Nitrogen (N) and/or phosphorus (P) limitations of algal growth were tested experimentally using nutrient- diffusing substrata (clay saucers filled with enriched agar) and enrichment of artificial channels. Addition of N and P in combination increased algal biomass (chlorophyll a and ash-free dry mass) over controls or single addition of N or P. Thus, algal biomass was N and P limited; however, individual taxa responded to specific N and/or P concentrations or atomic N:P ratio. Key words: flooding, intermittent stream, nitrate, nitrogen, nutrient limitation, organic nitrogen, periphyton, phosphorus, tallgrass prairie, stream

}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {http://www.jstor.org/stable/1937609}, author = {Tate, C.M.} } @article {KNZ00257, title = {Death Camas (Zigadenus nuttallii) in Kansas: pollen collectors and a florivore}, journal = {Journal of the Kansas Entomological Society}, volume = {62}, year = {1989}, pages = {411 -412}, abstract = {

All parts of plants of the genus Zigadenus (Liliaceae) contain numerous alkaloids through both vegetative and reproductive periods. The purpose of this note is to report the findings of incidental observations and insect collections made during a sutdy of the ecophysiologiy of Z. nuttallii

}, keywords = {LTER-KNZ, insect}, author = {Tepedino, V.J. and Alan K. Knapp and Eickwort, G.C. and Ferguson, D.C.} } @proceedings {KNZ00250, title = {Effects of manipulation on foliage characteristics of Andropgon gerardii Vitman}, year = {1989}, pages = {143 -146}, publisher = {University of Nebraska Press}, address = {Lincoln, NE}, abstract = {

The effects of burning, mowing, and nitrogen fertilizer on the chlorophyll, nitrogen, and phosphorus content of big bluestem were measured using a factorial experimental design at Konza Prairie Research Natural Area. While spring burning usually increased foliage production, burning had no effect on mid-season chlorophyll or nitrogen concentrations. Chlorophyll concentrations were significantly increased by fertilizer and mowing treatments. Nitrogen concentrations of foliage were higher on fertilized and mowed plots. Mowing also increased phosphorous concentrations of foliage, but nitrogen fertilizer significantly reduced phosphorus concentrations. These results support other research indicating that 1) nitrogen use efficiency (grams biomass produced per gram of foliage nitrogen) is higher on burned prairie, 2) removal of foliage by mowing results in more nutrient-rich regrowth, and 3) the amount of phosphorus available to big bluestem foliage is limited. The dilution of phosphorus caused by added nitrogen was a consequence of increased productivity on these plots and suggessts phosphorus uptake in excess of requirements for maximum growth. The relationships between burning, mowing, and nitrogen on the spectral reflectance patterns of vegetation indicated that chlorophyll (or nitrogen) concentrations of foliage appeared to more strongly affect indices of greenness and plant vigor than did the amount of plant biomass. Key words: biomass, burning, mowing, big bluestem, Andropogon gerardii, chlorophyll, nitrogen, phosphorus, Kansas

}, keywords = {LTER-KNZ, burning}, author = {Ramundo, R.A. and Shapley, T.D. and Turner, C.L. and Dyer, M.I. and Seastedt, T.R.}, editor = {Bragg, T.B. and Stubbendieck, J.} } @article {KNZ00211, title = {Differential use of experimental habitat patches by foraging Peromyscus maniculatus on dark and bright nights}, journal = {Journal of Mammalogy}, volume = {69}, year = {1988}, pages = {869 -872}, abstract = {

To assess the influence of illumination on choice of microhabitat by foraging rodents, we tested the use of exposed and protected patches by deer mice (Peromyscus maniculatus) when seeds were equally available in two or more patch types in large laboratory arenas. Based on field observations, we expected that, under higher levels of illumination, the ratio of foraging activity in exposed microhabitats to that in protected ones would be lower. We present data from three experiments that uphold this expectation

}, keywords = {LTER-KNZ}, doi = {10.2307/1381652}, author = {Travers, S.E. and D.W. Kaufman and Kaufman, G.A.} } @article {KNZ00178, title = {Hydrologic influences on leaf decomposition in a channel and adjacent bank of a gallery forest stream}, journal = {The American Midland Naturalist}, volume = {120}, year = {1988}, pages = {11 -21}, abstract = {

Hydrologic extremes of flooding and drought typically occur each year in prairie streams. Two experiments were conducted in a fifth- order, gallery forest reach of King\&$\#$39;s Creek, Kansas, to assess the effect of hydrologic conditions on decomposition of leaves in the stream channel and on the adjacent floodplain. Temporal patterns of weight loss were examined in the first experiment. Leaves of bur oak and hackberry decomposed more rapidly in the channel than on the adjacent bank. A sharp drop in percent remaining for hackberry in the 2nd month (mid- December to mid-January) coincided with a period of high shredder densities on hackberry leaves. On the bank, decomposition of hackberry leaves was fastest during intervals that included one or more inundations of the leaf packs. Bur oak leaves decomposed more slowly than hackberry leaves and were influenced less by the hydrologic history. In the second experiment, spatial variation in decomposition rate of hackberry leaves was examined by placing 20 pairs of leaf packs in a transect extending from the center of the stream channel on the top of the upper bank. Position on the transect affected the frequency and duration of inundations on the floodplain, which ranged from one (minimum of 0.2 hr) to 17 times (272 cumulative hr under water), while three pairs of packs in the channel were always under water. The logarithm of percent remaining after 274 days was significantly correlated with number of hours inundated and number of times inundated, although other factors such as soil moisture or amount of flood-deposited silt may have influenced differences in decomposition rates along the transect. We concluded that flood frequency, during and timing affected both spatial and temporal patterns of decomposition, especially of a fast-decomposing species, in the riparian forest of an intermittent prairie stream

}, keywords = {LTER-KNZ, gallery forest}, doi = {10.2307/2425882}, author = {Gurtz, M.E. and Tate, C.M.} } @article {KNZ00206, title = {Interactions among soil invertebrates, microbes and plant growth in tallgrass prairie}, journal = {Agriculture, Ecosystems, and Environment}, volume = {24}, year = {1988}, pages = {219 -228}, abstract = {

The tallgrass prairie of North American contains a diverse and abundant soil fauna well represented by earthworms, macro- and microarthopods and nematodes. A portion of this fauna representing a large fraction of the animal biomass has been introduced in the last 200 years, and functional roles and regulatory mechanisms may have been altered because of these introductions. Four years of experimental manipulations of plant and fauna variables have failed to establish a definitive net effect of the soil fauna on primary productivity. However, measurable effects of the fauna on nutrient dynamics of the grassland ecosystem have been observed. Experimental manipulations of plant root dynamics and addition of inorganic nitrogen and fixed carbon have demonstrated that both resources quality and resource quantity are factors limiting the size of soil fauna populations

}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1016/0167-8809(88)90067-9}, author = {Seastedt, T.R. and James, S.W. and Todd, T.C.} } @article {KNZ00161, title = {Experimental manipulations of soil arthropod, nematode, and earthworm communities in a North American tallgrass prairie}, journal = {Pedobiologia}, volume = {30}, year = {1987}, pages = {9 -17}, abstract = {An insecticide was applied to foliage and an insecticide-nematicide was applied to the soil surface of a North American tallgrass prairie site in an attempt to manipulate population densities of invertebrate consumers. The objectives of this study included 1) measurement of impacts of the dominant root herbivores, June beetle larvae (Phyllophaga spp.: Scarabaeidae) on plant root biomass and production; 2) to evaluate nematode and earthworm response to the chemicals and to correlate changes in these groups with changes in living or dead plant mass, and 3) to test if differences in densities of aboveground invertebrate consumer groups directly or indirectly affected population densities of the belowground groups. The last question resulted from an observation by Seastedt (1985) that moderate aboveground herbivory appears to increase population densities of soil nematodes and certain arthropod groups}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Seastedt, T.R. and Todd, T.C. and James, S.J.} } @article {KNZ00129, title = {Comparison of mass loss, nutrients, and invertebrates associated with elm leaf litter decomposition in perennial and intermittent reaches of tallgrass prairie streams}, journal = {The Southwestern Naturalist}, volume = {31}, year = {1986}, pages = {511 -520}, abstract = {

Decay rates, nutrient content and invertebrates associated with American elm leaves were examined in an intermittent and a perennial stream draining adjacent tallgrass prairie watersheds (Konza Prairie, Kansas). Both streams were flowing in November 1981 when leaf packs were placed in the channel. Elm leaves decayed faster in the perennial stream than in either of two intermittent sites. Decay rates were not different between the two intermittent sites. There were no significant differences among sites in either nitrogen (N) or phosphorus (P) concentrations or carbon to nitrogen (C:N) ratios in elm leaves. N concentrations of the leaves increased during decomposition whereas P decreased in concentration for the first two months and then increased; C:N ratios in elm leaves decreased during decomposition. Initial leaching of leaves may provide a nutrient input into prairie streams; but decomposing leaf material may also act as a nutrient sink and compete with other ecosystem processes. Shredder insects were low in abundance or absent from leaf packs

}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.2307/3671705}, author = {Tate, C.M. and Gurtz, M.E.} } @proceedings {KNZ0094, title = {The interaction of biological and hydrologic phenomena that mediate the quality of water draining native prairie on the Konza Prairie Research Natural Area}, journal = {Perspectives on Nonpoint Source Pollution}, year = {1985}, pages = {478 -482}, publisher = {U.S. Enviromental Protection Agency}, address = {Washington DC}, abstract = {

The quality of water from native landscapes in the baseline against which the impact of pollutants on surface water resources must be evaluated. The King\&$\#$39;s Creek watershed has been a U.S. Geological Survey benchmark watershed since 1979. It represents the landscape type tyat gave rise to much of the agricultural midwestern United States. Hydrologic, chemical, and biological measurements have been made by ecologists performing long-term ecological research (LTER) in tallgrass prairie. Streamwater chemistry varies seasonally with the amount and movement of groundwater and soil water, with changes in prairie vegetation, and in response to changes in surface water discharge. Concentrations of organic carbon, organ and inorganic nitrogen, and phosphorus increase during storm flows. The particulate fractions in transport and in storage in the stream bed and on the flood plain vary seasonally with recent hydrologic history and changes in vegetation

}, keywords = {LTER-KNZ, tallgrass prairie}, author = {McArthur, J.V. and Gurtz, M.E. and Tate, C.M. and Gilliam, F.S.} } @article {KNZ00101, title = {Long-term research in stream ecology}, journal = {Bulletin of the Ecological Society of America}, volume = {66}, year = {1985}, pages = {346 -353}, abstract = {

Many ecological phenomena occur on time scales of decades or centuries, and the need for long-term ecological research was recently emphasized in Likens\&$\#$39; presidential address to the Ecological Society. In the past it has been difficult to investigate these phenomena with financial support from funding agencies. However, in 1980 the National Science Foundation established the Long-Term Ecological Research Program (LTER). LTER-sponsored studies are now underway in 11 sites representing different ecosystem types. The purpose of this article is to describe briefly the general characteristics of each site involved with stream ecology and to summarize the nature and objectives of stream research at these sites

}, keywords = {LTER-KNZ, ecology, stream}, doi = {http://www.jstor.org/stable/20166454}, author = {Webster, J.R. and Blood, E.R. and Gregory, S.V. and Gurtz, M.E. and Sparks, R.E. and Thurman, E.M.} } @phdthesis {KNZ00100, title = {A study of temporal and spatial variations in nitrogen concentrations in a tallgrass prairie stream}, volume = {PhD Dissertation}, year = {1985}, pages = {1 -93}, school = {Kansas State University}, type = {Ph.D. Thesis}, address = {Manhattan, KS}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Tate, C.M.} } @mastersthesis {KNZ0074, title = {Autogamy as a fertility assurance strategy for forbs in the tallgrass prairie}, volume = {MS Thesis}, year = {1984}, pages = {1 -73}, school = {Kansas State University}, type = {M.S. Thesis}, address = {Manhattan, KS}, keywords = {LTER-KNZ, tallgrass prairie}, url = {http://krex.k-state.edu/dspace/handle/2097/27366}, author = {Townsend, D.K.} }