@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} } @article {KNZ001819, title = {Restoration and management for plant diversity enhances the rate of belowground ecosystem recovery}, journal = {Ecological Applications}, volume = {27}, year = {2017}, pages = {355 - 362}, abstract = {

The positive relationship between plant diversity and ecosystem functioning has been criticized for its applicability at large scales and in less controlled environments that are relevant to land management. To inform this gap between ecological theory and application, we compared recovery rates of belowground properties using two chronosequences consisting of continuously cultivated and independently restored fields with contrasting diversity management strategies: grasslands restored with high plant richness and managed for diversity with frequent burning (n = 20) and grasslands restored with fewer species that were infrequently burned (n = 15). Restoration and management for plant diversity resulted in 250\% higher plant richness. Greater recovery of roots and more predictable recovery of the active microbial biomass across the high diversity management strategy chronosequence corresponded with faster recovery of soil structure. The high diversity grasslands also had greater nutrient conservation indicated by lower available inorganic nitrogen. Thus, mesic grasslands restored with more species and managed for high plant diversity with frequent burning enhances the rate of belowground ecosystem recovery from long-term disturbance at a scale relevant to conservation practices on the landscape

}, keywords = {LTER-KNZ, Aggregates, Biodiversity, carbon, Ecosystem function, nitrogen, phospholipid fatty acid, prairie, root, soil}, doi = {10.1002/eap.1503}, url = {https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/eap.1503}, author = {Klopf, Ryan P. and S.G. Baer and E.M. Bach and Six, Johan} } @article {KNZ001632, title = {Eutrophication weakens stabilizing effects of diversity in natural grasslands}, journal = {Nature}, volume = {508}, year = {2014}, pages = {521 -525}, abstract = {

Studies of experimental grassland communities1, 2, 3, 4, 5, 6, 7 have demonstrated that plant diversity can stabilize productivity through species asynchrony, in which decreases in the biomass of some species are compensated for by increases in others1, 2. However, it remains unknown whether these findings are relevant to natural ecosystems, especially those for which species diversity is threatened by anthropogenic global change8, 9, 10, 11. Here we analyse diversity\–stability relationships from 41 grasslands on five continents and examine how these relationships are affected by chronic fertilization, one of the strongest drivers of species loss globally8. Unmanipulated communities with more species had greater species asynchrony, resulting in more stable biomass production, generalizing a result from biodiversity experiments to real-world grasslands. However, fertilization weakened the positive effect of diversity on stability. Contrary to expectations, this was not due to species loss after eutrophication but rather to an increase in the temporal variation of productivity in combination with a decrease in species asynchrony in diverse communities. Our results demonstrate separate and synergistic effects of diversity and eutrophication on stability, emphasizing the need to understand how drivers of global change interactively affect the reliable provisioning of ecosystem services in real-world systems.

}, keywords = {LTER-KNZ, Biodiversity, Community ecology, Grassland ecology}, doi = {10.1038/nature13014}, url = {https://www.nature.com/articles/nature13014}, author = {Hautier, Y. and Seabloom, E.W. and E.T. Borer and P. Adler and Harpole, W.S. and Hillebrand, H. and Lind, E.M. and MacDougall, A.S. and Stevens, C.J. and J.D. Bakker and Buckley, Y.M. and Chu, C. and Scott. L. Collins and Daleo, P. and Damschen, E.I. and Davies, K.F. and Fay, P.A. and Firn, J. and Gruner, D.S. and Jin, V.L. and Klein, J.A. and Knops, J.M.H. and Kimberly J. La Pierre and Li, W. and McCulley, R.L. and Melbourne, B.A. and Joslin L. Moore and O{\textquoteright}Halloran, L.R. and Prober, S.M. and A. Risch and Sankaran, M. and Schuetz, M. and Hector, A.} } @article {KNZ001619, title = {Invertebrates, ecosystem services and climate change}, journal = {Biological Reviews}, volume = {88}, year = {2013}, pages = {327 -348}, abstract = {

The sustainability of ecosystem services depends on a firm understanding of both how organisms provide these services to humans and how these organisms will be altered with a changing climate. Unquestionably a dominant feature of most ecosystems, invertebrates affect many ecosystem services and are also highly responsive to climate change. However, there is still a basic lack of understanding of the direct and indirect paths by which invertebrates influence ecosystem services, as well as how climate change will affect those ecosystem services by altering invertebrate populations. This indicates a lack of communication and collaboration among scientists researching ecosystem services and climate change effects on invertebrates, and land managers and researchers from other disciplines, which becomes obvious when systematically reviewing the literature relevant to invertebrates, ecosystem services, and climate change. To address this issue, we review how invertebrates respond to climate change. We then review how invertebrates both positively and negatively influence ecosystem services. Lastly, we provide some critical future directions for research needs, and suggest ways in which managers, scientists and other researchers may collaborate to tackle the complex issue of sustaining invertebrate-mediated services under a changing climate.

}, keywords = {LTER-KNZ, Biodiversity, bioindicator species, Climate change, ecosystem engineers, ecosystem services, insects, invertebrates, sustainability}, doi = {10.1111/brv.12002}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/brv.12002}, author = {Prather, C.M. and Pelini, S. and Laws, A. and Rivest, E. and Woltz, M. and Bloch, C.P. and Del Toro, I. and Ho, Chuan-Kai. and Kominoski, J. and Newbold, T.A.S. and Parsons, S. and Anthony Joern} } @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.} } @mastersthesis {KNZ001331, title = {Factors affecting denitrification in headwater prairie streams}, volume = {MS Thesis}, year = {2010}, school = {Kansas State University}, type = {M.S. Thesis}, address = {Manhattan, KS}, abstract = {

Human-induced stressors such as increased nitrogen (N) loadings, altered watershed land-use, and biodiversity losses are a few of the numerous threats to aquatic systems. Prairie streams experience natural disturbances, such as flooding and desiccation, which may alter responses to anthropogenic stressors. Denitrification, the dissimilatory reduction of NO3- to N gas (N2O or N2), is the only permanent form of N removal from terrestrial or aquatic ecosystems, and is important in mitigating N pollution to streams and downstream waters. Little is known about the relationships between denitrification and riparian prairie vegetation or large consumers. In the first chapter, I used outdoor mesocosms to determine the impact of a grazing minnow, Campostoma anomalum, on structural and functional responses of prairie streams to a simulated flood, focusing on denitrification. In terrestrial ecosystems, grazing can stimulate denitrification, but this has not been studied in streams. Ammonium (NH4+) enrichments, used to simulate fish excretion, alleviated N limitations on denitrification. Both fish and NH4+ affected algal biomass accrual, but only fish affected algal filament lengths and particulate organic matter. In a second experiment, I examined the impact of woody vegetation expansion, a primary threat to tallgrass prairie, on riparian and benthic denitrification. Expansion of woody vegetation in these grasslands is due primarily to altered fire regimes, which historically inhibited woody vegetation growth. To determine the effect of woody vegetation expansion on benthic and riparian denitrification, woody vegetation was removed from the riparian zone of a grazed and an ungrazed watershed. Both soil and benthic denitrification rates from this removal buffer were compared to rates in grassy or woody riparian zones. Riparian soil denitrification was highly seasonal, with greatest rates occurring during early spring, and rates being low throughout the remainder of the year. Benthic denitrification was also temporally variable but did not exhibit seasonal trends, suggesting benthic denitrification is driven by factors other than water temperature. Removal of woody vegetation stimulated soil and benthic denitrification rates over rates found in naturally vegetated riparian zones. Elevated N loadings will continue to affect aquatic ecosystems, and these effects may be exacerbated by biodiversity losses or changing riparian vegetation.

}, keywords = {LTER-KNZ, Biodiversity, denitrification, Ecosystem recovery, nitrogen, prairie streams, woody encroachment}, url = {http://hdl.handle.net/2097/4273}, author = {Reisinger, A.J.} } @article {KNZ001166, title = {Coexisting generalist herbivores occupy unique nutritional feeding niches}, journal = {Proceedings of the National Academy of Sciences}, volume = {105}, year = {2008}, pages = {1977 -1982}, abstract = {

A mainstay of ecological theory and practice is that coexisting species use different resources, leading to the local development of biodiversity. However, a problem arises for understanding coexistence of multiple species if they share critical resources too generally. Here, we employ an experimental framework grounded in nutritional physiology to show that closely related, cooccurring and generalist-feeding herbivores (seven grasshopper species in the genus Melanoplus; Orthoptera: Acrididae) eat protein and carbohydrate in different absolute amounts and ratios even if they eat the same plant taxa. The existence of species-specific nutritional niches provides a cryptic mechanism that helps explain how generalist herbivores with broadly overlapping diets might coexist. We also show that performance by grasshoppers allowed to mix their diets and thus regulate their protein\–carbohydrate intake matched optimal performance peaks generated from no-choice treatments. These results indicate the active nature of diet selection to achieve balanced diets and provide buffering capacity in the face of variable food quality. Our empirical findings and experimental approach can be extended to generate and test predictions concerning the intensity of biotic interactions between species, the relative abundance of species, yearly fluctuations in population size, and the nature of interactions with natural enemies in tritrophic niche space.

}, keywords = {LTER-KNZ, Biodiversity, Competition, geometric framework, physiological ecology, resource partitioning}, doi = {10.1073/pnas.0711870105}, url = {https://www.pnas.org/content/105/6/1977}, author = {Behmer, S.T. and Anthony Joern} } @article {KNZ001049, title = {Can rDNA analyses of diverse fungal communities in soil and rootsdetect effects of environmental manipulations--a case study from tallgrass prairie}, journal = {Mycologia}, volume = {97}, year = {2005}, pages = {1177 -1194}, abstract = {

We tested whether fungal communities are impacted by nitrogen deposition or increased precipitation by PCR-amplifying partial fungal rRNA genes from 24 soil and 24 root samples from a nitrogen enrichment and irrigation experiment in a tallgrass prairie at Konza Prairie Biological Station in northeastern Kansas, U.S.A. Obtained fungal sequences represented great fungal diversity that was distributed mainly in ascomycetes and basiodiomycetes; only a few zygomycetes and glomeromycetes were detected. Conservative extrapolated estimates of the fungal species richness suggest that the true richness may be at least twice as high as observed. The effects of nitrogen enrichment or irrigation on fungal community composition, diversity or clone richness could not be unambiguously assessed because of the overwhelming diversity. However, soil communities differed from root communities in diversity, richness and composition. The compositional differences were largely attributable to an abundant, soil-inhabiting group placed as a well-supported sister group to other ascomycetes. This group likely represents a novel group of fungi. We conclude that the great fungal richness in this ecosystem precluded a reliable assessment of anthropogenic impacts on soil or rhizosphere communities using the applied sampling scheme, and that detection of novel fungi in soil may be more a rule than an exception.

}, keywords = {LTER-KNZ, Biodiversity, environmental change, fungi, nitrogen, Precipitation, soil DNA}, doi = {10.3852/mycologia.97.6.1177}, author = {A. Jumpponen and Johnson, L.C.} } @article {KNZ001024, title = {Indicators of plant species richness in AVIRIS spectra of a mesic grassland}, journal = {Remote Sensing of Environment}, volume = {98}, year = {2005}, pages = {304 -316}, abstract = {Hyperspectral imagery of the Konza Prairie Biological Station in northeastern Kansas was used to evaluate upwelling spectral radiance, prairie spectral reflectance and band ratios of each as potential indicators of vascular plant species richness in a mesic grassland. The extent to which spatial variability in these parameters related to plant species richness also was investigated. A 224 channel hyperspectral data cube acquired in June 2000 by the Airborne Visible and Infrared Imaging Spectrometer (AVIRIS) provided complete coverage of the 400{\textendash}2500 nm range at approximately 10 nm per channel. After band deletions accounted for detector overlap and strong atmospheric attenuation features, 176 bands were retained for analysis and spanned the 404{\textendash}2400 nm range. Prairie reflectance was estimated via radiative transfer modeling and scaling to a library spectrum of highway construction material. Data were sampled from pixels having a 19 m ground sample distance (GSD) to represent each of 93 vegetation sampling transects. Reflectance and radiance at mid-infrared wavelengths (e.g., 1553 nm), and band ratios that were based on atmospheric windows in the red, near-infrared and mid-infrared spectra estimated species richness to within 6 to 7 species per transect. The 856 to 780 nm radiance or reflectance ratio yielded maximum adjusted coefficients of determination (r2) of approximately 0.4 in regressions with richness when data from bison-grazed and ungrazed areas were combined. These regressions remained significant (p <= 0.001) when only ungrazed areas were assessed although r2 reduced to approximately 0.2. Richness was related significantly also to the 433 to 674 nm reflectance ratio for grazed-plus-ungrazed and ungrazed-only areas. In contrast, the effectiveness of the 433 to 674 nm radiance ratio was reduced by atmospheric backscatter. Species richness did not correlate strongly or consistently with transect spatial variability (coefficient of variation or range) in radiance, reflectance or band ratio value, apparently as a consequence of the relatively small area sampled for each transect (approximately 0.5 ha). Relationships between richness and prairie spectral features were explained by the influence of soil exposure on both parameters. Richness and estimated soil exposure tended to increase from ungrazed lowlands, to ungrazed slopes, to ungrazed uplands to grazed areas. Remotely sensed estimates of soil exposure may be particularly useful in addressing plant species richness on grazed grasslands owing to an overall similarity in spectral reflectance among dominant plant species.}, keywords = {LTER-KNZ, AVIRIS, Biodiversity, Bison grazing, grassland, Hyperspectral, Plant species richness, Radiance, Reflectance, Soil exposure, Spatial variability, Spectral mixing}, doi = {10.1016/j.rse.2005.08.001}, author = {Carter, G.A. and Alan K. Knapp and Anderson, J.E. and Hoch, G.A. and M.D. Smith} } @article {KNZ00879, title = {Grazing management effects on plant species diversity in tallgrass prairie}, journal = {Journal of Range Management}, volume = {57}, year = {2004}, pages = {58 -65}, abstract = {A 6-year study was conducted in tallgrass prairie to assess the effects of grazing management (cattle stocking densities and grazing systems) on plant community composition and diversity. Treatments included sites grazed season-long (May to October) at 3 stocking densities (3.8, 2.8, and 1.8 hectares per animal unit), ungrazed control sites, and sites under a late-season rest rotation grazing system at this same range of stocking densities. Plant communities were sampled twice each season using a nearest-point procedure. Native plant species diversity, species richness, and growth form diversity were significantly higher in grazed compared to ungrazed prairie, and diversity was greatest at the highest stocking density. This enhancement of plant species diversity under grazing was not a result of increased frequency of weedy/exotic species. There were no significant effects of grazing system on plant diversity, nor any significant stocking density {\texttimes} grazing system interactions, indicating that animal density is a key management variable influencing plant species diversity and composition in tallgrass prairie and that effects of animal density override effects of grazing systems. Increasing cattle stocking densities decreased the abundance of the dominant perennial tall grasses, and increased abundance of the C4 perennial mid-grasses. The frequency of perennial forbs was relatively stable across grazing treatments. Abundance of annual forbs varied among years and grazing treatments. In half of the years sampled, annual forbs showed the highest frequency under intermediate stocking density. Patterns of responses among plant groups suggest that some species may respond principally to direct effects of grazers and others may respond to indirect effects of grazers on competitive relationships or on the spatial patterns of fuel loads and fires. Thus, this study suggests that large grazer densities, fire, and annual climatic variability interact to influence patterns of plant community composition and diversity in tallgrass prairie. Effects of varying management such as stocking densities and grazing systems on plant species diversity and the relative abundances of different plant growth forms or functional groups may have important consequences for grassland community stability and ecosystem function.}, keywords = {LTER-KNZ, Biodiversity, cattle grazing, Flint Hills, grazing systems, plant ecology, range management, stocking rates}, doi = {10.2111/1551-5028(2004)057[0058:GMEOPS]2.0.CO;2}, author = {Hickman, K.R. and D.C. Hartnett and Cochran, R.C. and Owensby, C.E.} } @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 {KNZ00794, title = {Analytical survey of the braconid wasp fauna (Hymenoptera: Braconidae) on six Midwestern U.S. tallgrass prairies}, journal = {Annals of the Entomological Society of America}, volume = {94}, year = {2001}, pages = {230 -238}, abstract = {A survey of the braconid wasps on midwestern United States tallgrass prairies was conducted using malaise trapping on six sites forming an east-west transect through the prairie zone in Kansas, Missouri, and Illinois. A total of 924 specimens, representing 184 species, was recovered. Statistical analyses indicated that the asymptote of actual species richness had not yet been approached using this sampling regime. Nevertheless, this is the most complete survey yet available of prairie braconid wasps. Patterns of distinctness of the prairie fauna relative to that of other nearby plant communities are beginning to emerge.}, keywords = {LTER-KNZ, Biodiversity, Braconidaek, Grasslands, parasitoids, tallgrass prairies}, doi = {10.1603/0013-8746(2001)094[0230:ASOTBW]2.0.CO;2}, author = {Whitfield, J.B. and Lewis, C.N.} } @article {KNZ00756, title = {Determinants of C3 forb growth and production in a C4 dominated grassland}, journal = {Plant Ecology}, volume = {152}, year = {2001}, pages = {93 -100}, abstract = {Forbs are the most abundant species within the vascular flora of tallgrass prairie and they make the greatest contribution to biodiversity of all growth forms. However, little is known about the factors that determine their productivity and growth rates. The objective of this study was to assess the controls of forb growth (absolute and relative) and production in tallgrass prairie from a long-term burning experiment at the Konza Prairie in NE Kansas. Over the 14-year study, forbs comprised 9\% of the total biomass production on sites with a high fire frequency vs. 29\% on the low fire frequency site, with gramminoids accounting for the remainder. Although interannual variations in peak biomass of the grasses was strongly correlated with environmental variables related to water availability, there were no similar relationships for forbs, suggesting that production of forbs and grasses responded to interannual variations in climate in different ways. Multivariate analysis of climatic controls on growth rates of grasses and forbs yielded similar results. Although forbs had low biomass and absolute growth per unit ground area in frequently burned prairie, their relative growth rates were highest in such sites. Thus, it appears that reduced growth rates of individual forbs per se do not limit forb success in annually burned prairie. Instead, direct negative effects of fire on forbs (increased mortality) may be responsible. Determinants of forb growth and productivity in unburned prairie remain unresolved.}, keywords = {LTER-KNZ, aboveground net primary production, Biodiversity, fire, forbs, Graminoids, Relative growth rates, tallgrass prairie}, doi = {10.1023/A:1011400101014}, author = {J. M. Briggs and Alan K. Knapp} }