@article {KNZ001568, title = {Cessation of burning dries soils long-term in a tallgrass prairie}, journal = {Ecosystems}, volume = {17}, year = {2014}, pages = {54 -65}, abstract = {

Soil moisture is a critical variable in grassland function, yet how fire regimes influence ecohydrology is poorly understood. By altering productivity, species composition, and litter accumulation, fire can indirectly increase or decrease soil water depletion on a range of time scales and depths in the soil profile. To better understand how fire influences soil moisture in grasslands, we analyzed 28 years of soil moisture data from two watersheds in a central North American grassland which differ in their long-term fire frequency. Across 28 years, cessation of prescribed burning initially led to wetter soils, likely as litter accumulated and both transpiration and evaporation were suppressed. Long-term, cessation of burning led to soils drying more, especially at depths greater than 75 cm. The long-term drying of deep soils is consistent with the increase in woody species in the infrequently burned grassland as woody species likely have a greater reliance on soil water from deeper soil layers compared to co-occurring herbaceous species. Despite the ecohydrological changes associated with the cessation of prescribed burning, watersheds with different burn regimes responded similarly to short-term variation in climate variation. In both watersheds, low precipitation and high temperatures led to drier soils with greater responses in soil moisture to climate variation later in the season than earlier. There is no current evidence that the cessation of burning in this ecosystem will qualitatively alter how evapotranspiration responds to climate variation, but the use of deeper soil water by woody plants has the potential for greater transpiration during dry times. In all, modeling the depth-specific responses of soil moisture and associated ecosystem processes to changes in burn regimes will likely require including responses of plant community composition over short and long time scales.

}, keywords = {LTER-KNZ, critical climate period, ecohydrology, Evapotranspiration, fire, Konza Prairie, soil moisture, woody species}, doi = {10.1007/s10021-013-9706-8}, url = {https://link.springer.com/article/10.1007\%2Fs10021-013-9706-8}, author = {Craine, J.M. and Jesse B. Nippert} } @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 {KNZ001607, title = {Lack of eutrophication in a tallgrass prairie ecosystem over 27 years}, journal = {Ecology}, volume = {95}, year = {2014}, pages = {1225 -1235}, abstract = {

Many North American grasslands are receiving atmospheric nitrogen (N) deposition at rates above what are considered critical eutrophication thresholds. Yet, potential changes in grassland function due to anthropogenic N deposition are poorly resolved, especially considering that other dynamic factors such as land use and precipitation can also affect N availability. To better understand whether elevated N deposition has altered ecosystem structure or function in North American grasslands, we analyzed a 27-year record of ecophysiological, community, and ecosystem metrics for an annually burned Kansas tallgrass prairie. Over this time, despite increasing rates of N deposition that are within the range of critical loads for grasslands, there was no evidence of eutrophication. Plant N concentrations did not increase, soil moisture did not decline, forb diversity did not decline, and the relative abundance of dominant grasses did not shift toward more eutrophic species. Neither aboveground primary productivity nor N availability to plants increased. The fates of deposited N in grasslands are still uncertain, and could include management losses through burning and grazing. However, evidence from this grassland indicates that eutrophication of North American grassland ecosystems is not an inevitable consequence of current levels of N deposition.

}, keywords = {LTER-KNZ}, doi = {10.1890/13-1068.1}, url = {https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/13-1068.1}, author = {McLauchlan, K.K. and Craine, J.M. and Jesse B. Nippert and Ocheltree, T.W.} } @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 {KNZ001552, title = {The importance of timing of precipitation for grassland productivity}, journal = {Plant Ecology}, volume = {213}, year = {2013}, pages = {1085 -1089}, abstract = {

Future climate change is likely to involve changes in the amount and intensity of precipitation, but also its timing during the year. To better understand how the timing of precipitation impacts plant productivity, a 27-year dataset on grass productivity for a mesic North American grassland was analyzed. Along with other climate parameters, the ability of the average date precipitation fell during different climate periods to explain grass productivity was tested. Across the 27 years, grass productivity was greater in years with more precipitation between April 15 and August 2. After accounting for differences in the total amount of precipitation during this time period, in years when precipitation between May 9 and August 27 fell later, measured grass productivity was less. Variation among years in precipitation timing was of similar importance as temperatures during critical climate periods and about 40 \% of the importance of the total amount of precipitation. In all, although the mechanisms generating these responses are uncertain, precipitation timing within a growing season has substantial effects on productivity.

}, keywords = {LTER-KNZ, critical climate period, Grasslands, Konza Prairie, Precipitation, Primary productivity, Timing}, doi = {10.1007/s11258-013-0236-4}, url = {https://link.springer.com/article/10.1007\%2Fs11258-013-0236-4}, author = {Craine, J.M.} } @article {KNZ001547, title = {Long-term climate sensitivity of grazer performance: a cross-site study}, journal = {PLOS ONE}, volume = {8}, year = {2013}, pages = {67065 -}, abstract = {

Climate change will affect grasslands in a number of ways, but the consequences of a warmer, drier world for grazers is uncertain. Predicting future grazer performance is complex since climate change affects both the quantity and quality of forage through a combination of processes that occur over a range of time scales. To better predict the consequences of climate change for grazer performance, a dataset was compiled of over a quarter million bison weights distributed across 22 US herds that span a large range of climates. Patterns of bison body mass among sites, age classes, and sexes were analyzed with respect to differences in geographic patterns of climate and interannual variation in climate. While short-term effects of climate variability are likely to depend on the magnitude and timing of precipitation during the year, grazers will be negatively affected by sustained hotter, drier conditions most likely associated with reductions in forage quality. Short-term, little effect of high temperatures on bison performance is observed, which suggests that the long-term effects of higher temperatures are likely to accrue over time as nitrogen availability in grasslands is reduced and forage quality declines. If relationships observed for bison are general for cattle, the economic consequences of higher temperatures due to decreased weight gain in US cattle could be on the order of US$1B per 1\°C increase in temperature. Long-term monitoring of forage quality as well as native and domesticated grazer performance is recommended to better understand climate change effects on grazers.

}, keywords = {LTER-KNZ, Animal performance, bison, Cattle, Climate change, Grasses, Grasslands, Meteorology, Weight gain}, doi = {10.1371/journal.pone.0067065}, url = {https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0067065}, author = {Craine, J.M.} } @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 {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 {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.} } @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 {KNZ001501, title = {Root characteristics of C-4 grasses limit reliance on deep soil water in tallgrass prairie}, journal = {Plant and Soil}, volume = {355}, year = {2012}, pages = {385 -394}, abstract = {

Background C4 grass species in the mesic tallgrass prairie of central North America can exhibit both high root production and deep rooting in the soil profile (\>2 m). Differences in root growth and the types of roots produced vary according to local environmental gradients and management practices. The production of deep roots in tallgrass prairie has been historically presumed as a mechanism for water uptake when surface soils are dry. Methods We examined changes in root biomass, total root length, root width, and theoretical hydraulic conductivity using roots collected from deep soil cores in upland and lowland topographic positions in grazed and ungrazed watersheds of the Konza Prairie Biological Station in north-eastern Kansas, USA. Results Root biomass, total root length, and theoretical hydraulic conductivity were highest in roots found in the top 20 cm of the soil profile, and then declined exponentially with increasing soil depth. Compared to grazed areas, ungrazed locations had more root biomass and total root length of roots in the most superficial soil layers. No differences in rooting profiles were present among topographic contrasts. Theoretical hydraulic conductivity of axial root xylem did not vary by topographic position or grazing contrasts, and declines in conductivity by depth were driven by changes in the number of vessels per stele, rather than changes in vessel size. Conclusions Irrespective of differences by grazing treatment or topographic position, significant reductions in root biomass, total root length, and theoretical hydraulic conductivity of grass roots at soil depths greater than 1 m suggest deep roots in this grassland have limited functional significance for water uptake.

}, keywords = {LTER-KNZ, Andropogon gerardii, C4 grass, Mesic grassland, Root biomass, Theoretical hydraulic conductivity, Total root length}, doi = {10.1007/s11104-011-1112-4}, url = {https://link.springer.com/article/10.1007\%2Fs11104-011-1112-4}, author = {Jesse B. Nippert and Wieme, R.A. and Ocheltree, T.W. and Craine, J.M.} } @article {KNZ001464, title = {The timing of climate variability and grassland productivity}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {109}, year = {2012}, pages = {3401 -3405}, 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 Jesse B. Nippert and Elmore, A.J. and Skibbe, A.M. and Hutchinson, S.L. and N. Brunsell} } @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 {KNZ001426, title = {Interannual variability of pollen productivity and transport in mid-North America from 1997 to 2009}, journal = {Aerobiologia}, volume = {27}, year = {2011}, pages = {181 -189}, abstract = {

Understanding the causes of interannual variability in atmospheric pollen concentration is an important but elusive goal for public health and environmental change. We analyzed long-term daily records of pollen counts from urban Kansas City, Missouri, USA collected from 1997 to 2009 for three pollen groups: Ambrosia, Poaceae, and a third group which is mostly composed of arboreal pollen types. The annual pollen index varied from 8,368 to 80,822 over the thirteen-year period. Although Ambrosia pollen is often thought to be associated with droughts and disturbance, years with high Ambrosia pollen were associated with high summer precipitation to the south of Kansas City. Years with high Poaceae pollen were associated with high spring precipitation to the south of the city. In support of the southern influence to Kansas City pollen, Ambrosia and Poaceae pollen mostly arrived on southern winds. In contrast to the other two pollen groups, the arboreal pollen was most associated with growing season precipitation to the east of Kansas City, although it was still highest on days with southern winds. Based on the correlations with climate, the severity of an upcoming allergy season may be predicted with early-season precipitation data, while short-term severity can be forecast from local weather patterns.

}, keywords = {LTER-KNZ, climate, grass, Great Plains, Pollen, Ragweed}, doi = {10.1007/s10453-010-9186-7}, url = {https://link.springer.com/article/10.1007\%2Fs10453-010-9186-7}, author = {McLauchlan, K.K. and Barnes, C.S. and Craine, J.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} } @article {KNZ001361, title = {Soil moisture controls on temperature sensitivity of soil organic carbon decomposition for a mesic grassland}, journal = {Soil Biology and Biochemistry}, volume = {43}, year = {2011}, pages = {455 -457}, abstract = {

We examined relationships between soil moisture and the temperature sensitivity of decomposition of labile soil organic carbon at a central North American grassland. For soils collected from shallow, xeric uplands, temperature sensitivity was greatest at intermediate soil moisture. For soils collected from the deeper, mesic lowlands, temperature sensitivity increased with increasing soil moisture. For example, lowland soils incubated at 75\% WHC exhibited an apparent activation energy (Ea) that was 15 kJ mol\−1 greater than soils incubated at 30\% WHC, the equivalent of a Q10 of 2.8 vs. 2.3. Although further research is still needed to understand why moisture\–temperature sensitivity relationships would differ between topographic positions, the magnitude of the soil moisture effect is large enough to alter soil C budgets and should be considered explicitly when predicting ecosystem responses to global change scenarios.

}, keywords = {LTER-KNZ, grassland, Microbial respiration, soil moisture, Soil organic carbon, Temperature sensitivity, Warming}, doi = {10.1016/j.soilbio.2010.10.011}, url = {https://www.sciencedirect.com/science/article/abs/pii/S0038071710003949?via\%3Dihub}, author = {Craine, J.M. and Gelderman, T.M.} } @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 {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 {KNZ001274, title = {Plant nitrogen and phosphorus limitation in 98 North American grassland soils}, journal = {Plant and Soil}, volume = {334}, year = {2010}, pages = {73 -84}, abstract = {

The availability of nutrients is a critical determinant of ecological dynamics in grasslands, but the relationships between soil resource availability and nutrient limitation across ecosystems are not clear. To better understand how soil nutrient availability determines nutrient limitation in vegetation, we grew the same species of grass (Schizachyrium scoparium) in 98 North American grassland soils and fertilized them factorially with nitrogen (N) and phosphorus (P). On average adding N, P, and the two nutrients together increased biomass relative to unfertilized plants by 81\%, 22\%, and 131\%, respectively. Plants grown on low-P soils were not primarily limited by P. Instead, these plants were colimited by N and P, while plants grown on high-P soils were primarily limited by N and only secondarily limited by P. Limitation was not predicted by total soil N. The preponderance of colimitation between N and P on low-P soils suggests that low P availability alters the N cycle to constrain supplies to plants such that N and P are made available in proportion to their demand by plants.

}, keywords = {LTER-KNZ, Colimitation, Grasslands, nitrogen, Phosphorus, stoichiometry}, doi = {10.1007/s11104-009-0237-1}, url = {https://link.springer.com/article/10.1007\%2Fs11104-009-0237-1}, author = {Craine, J.M. and Jackson, R.D.} } @article {KNZ001304, title = {Thirteen decades of foliar isotopes indicate declining nitrogen availability in central North American grasslands}, journal = {New Phytologist}, volume = {187}, year = {2010}, pages = {1135 -1145}, abstract = {

\•Humans are increasing both the deposition of reactive nitrogen (N) and concentrations of atmospheric CO2 on Earth, but the combined effects on terrestrial ecosystems are not clear. In the absence of historical records, it is difficult to know if N availability is currently increasing or decreasing on regional scales. \•To determine the nature and timing of past changes in grassland ecosystem dynamics, we measured the composition of stable carbon (C) and N isotopes in leaf tissue from 545 herbarium specimens of 24 vascular plant species collected in Kansas, USA from 1876 to 2008. We also parameterized a simple model of the terrestrial N cycle coupled with a stable isotope simulator to constrain processes consistent with observed patterns. \•A prolonged decline in foliar N concentrations began in 1926, while a prolonged decline in foliar δ15N values began in 1940. Changes in the difference between foliar and atmospheric C isotopes reveal slightly increased photosynthetic water use efficiency since 1876. \•The declines in foliar N concentrations and foliar δ15N suggest declining N availability in these grasslands during the 20th century despite decades of anthropogenic N deposition. Our results are consistent with progressive-nitrogen-limitation-type hypotheses where declines in N availability are driven by increased ecosystem N storage as a result of increased atmospheric CO2.

}, keywords = {LTER-KNZ}, doi = {10.1111/j.1469-8137.2010.03322.x}, url = {https://nph.onlinelibrary.wiley.com/doi/full/10.1111/j.1469-8137.2010.03322.x}, author = {McLauchlan, K.K. and Ferguson, C.J. and Wilson, I.E. and Ocheltree, T.W. and Craine, J.M.} } @article {KNZ001354, title = {Widespread coupling between the rate and temperature sensitivity of organic matter decay}, journal = {Nature Geoscience}, volume = {3}, year = {2010}, pages = {854 -857}, abstract = {

Microbial breakdown of soil organic matter influences the potential for terrestrial ecosystems to sequester carbon, and the amount of carbon dioxide released to the atmosphere1, 2, 3, 4. Predicting the sensitivity of microbial decomposition to temperature change is therefore critical to predicting future atmospheric carbon dioxide concentrations and feedbacks to anthropogenic warming5. According to enzyme kinetics, the more biogeochemically recalcitrant the organic matter, the greater the temperature sensitivity of microbial respiration6, 7, 8. Here, we measured the temperature sensitivity of microbial respiration in soils from 28 sites in North America, ranging from Alaska to Puerto Rico, to test the generality of this principle. We show that the lower the rate of respiration at a reference temperature of 20\ \°C\—and thus the more biogeochemically recalcitrant the organic matter\—the greater the temperature sensitivity of soil respiration. We compiled our findings with those from other studies, encapsulating a range of environments, and show that this relationship holds across multiple scales and soil types. Although physico-chemical protection of soil organic matter and substrate availability will also influence the temperature sensitivity of decomposition, we suggest that biogeochemically recalcitrant organic matter will respond the most sensitively to anticipated warming.

}, keywords = {LTER-KNZ, Biogeochemistry, Microbial ecology}, doi = {10.1038/ngeo1009}, url = {https://www.nature.com/articles/ngeo1009}, author = {Craine, J.M. and Fierer, N. and McLauchlan, K.K.} } @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 {KNZ001275, title = {Landscape-level variation in temperature sensitivity of soil organic carbon decomposition}, journal = {Soil Biology \& Biochemistry}, volume = {42}, year = {2009}, pages = {373 -375}, abstract = {

We examined landscape-level variation in temperature sensitivity of labile SOC across 71 sites at a central North American grassland. The observed range in activation energy of decomposition (Ea), an index of temperature sensitivity, was as great at the landscape scale as has been observed at the continental scale. Ea was lower for soils with more labile C, consistent with the \‘Carbon quality-temperature\’ hypothesis. Soil pH explained 67\% of the variation in Ea. Although there are strong environmental correlates with the Ea of SOC decomposition at landscape scales, the amount of variation within landscapes could confound regional- to global-scale predictions of the response of soil C to warming.

}, keywords = {LTER-KNZ, grassland, Microbial respiration, Soil organic carbon, Temperature sensitivity, Warming}, doi = {10.1016/j.soilbio.2009.10.024}, url = {https://www.sciencedirect.com/science/article/abs/pii/S0038071709004015?via\%3Dihub}, author = {Craine, J.M. and Spurr, R. and McLauchlan, K.K. and Fierer, N.} } @article {KNZ00985, title = {Environmental constraints on a global relationship among leaf and root traits of grasses}, journal = {Ecology}, volume = {86}, year = {2005}, pages = {12 -19}, abstract = {Uncertainties regarding the relationships between leaf and root traits have impeded an integrated understanding of plant evolution and the efficient parameterization of ecosystem models. We measured key root and leaf traits of grasses from 77 sites in four grassland regions of the world (New Zealand, Australia, South Africa, North America). Within each region, the relationships among leaf traits paralleled those among root traits. Plants with low root or leaf N concentrations had roots or leaves with high tissue density, high lignin concentrations, low amount of mass that was soluble in a neutral detergent solution, large diameter/thickness, and were less enriched in 15N. Yet, whether comparing plants within a region or among all four regions, there was little relationship between root traits and leaf traits, except for a positive relationship between root and leaf N concentration and between root and leaf δ15N. At the global scale, factors such as soil freezing and the type of nutrient limitation appear to determine relationships among leaves and roots. C4 grasses not only had lower leaf N concentrations than C3 grasses but also lower root N concentrations. When compared at the same root N concentration, C4 grasses had greater leaf N concentrations than C3 grasses.}, keywords = {LTER-KNZ}, doi = {10.1890/04-1075}, author = {Craine, J.M. and Lee, W.G. and Bond, W.J. and Willians, R.J. and Johnson, L.C.} }