02581nas a2200217 4500008004100000245007000041210006900111300001100180490000700191520192800198653002802126653001702154653002302171653000902194653001802203653001802221653001802239100001702257700002302274856006602297 2014 eng d00aCessation of burning dries soils long-term in a tallgrass prairie0 aCessation of burning dries soils longterm in a tallgrass prairie a54 -650 v173 a

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.

10acritical climate period10aecohydrology10aEvapotranspiration10afire10aKonza Prairie10asoil moisture10awoody species1 aCraine, J.M.1 aNippert, Jesse, B. uhttps://link.springer.com/article/10.1007%2Fs10021-013-9706-802086nas a2200229 4500008004100000245010700041210006900148300001300217490000800230520136700238653002301605653001601628653001501644653001301659653001801672653002401690100001701714700001601731700002001747700002301767856006601790 2012 eng d00aCommunity traitscape of foliar nitrogen isotopes reveals N availabiity patterns in a tallgrass prairie0 aCommunity traitscape of foliar nitrogen isotopes reveals N avail a395 -4030 v3563 a

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.

10aCommunity assembly10adisturbance10aGrasslands10aIsotopes10aKonza Prairie10aResource limitation1 aCraine, J.M.1 aTowne, E.G.1 aOcheltree, T.W.1 aNippert, Jesse, B. uhttps://link.springer.com/article/10.1007%2Fs11104-012-1141-702015nas a2200157 4500008004100000245004900041210004900090300001500139490000700154520155200161100001701713700001701730700001601747700001701763856007701780 2010 eng d00aClimate change and cattle nutritional stress0 aClimate change and cattle nutritional stress a2901 -29110 v163 a

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.

1 aCraine, J.M.1 aElmore, A.J.1 aOlson, K.C.1 aTolleson, D. uhttps://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2486.2009.02060.x02131nas a2200145 4500008004100000245009200041210006900133300001500202490000700217520163100224100001701855700001601872700002301888856007401911 2010 eng d00aClimate controls on grass culm production over a quarter century in a tallgrass prairie0 aClimate controls on grass culm production over a quarter century a2132 -21400 v913 a

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.

1 aCraine, J.M.1 aTowne, E.G.1 aNippert, Jesse, B. uhttps://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/09-1242.102011nas a2200157 4500008004100000245009000041210006900131300001300200490000700213520148500220100001701705700001601722700001901738700001901757856007701776 2009 eng d00aConsequences of climate variability for the performance of bison in tallgrass prairie0 aConsequences of climate variability for the performance of bison a772 -7790 v153 a

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.

1 aCraine, J.M.1 aTowne, E.G.1 aJoern, Anthony1 aHamilton, R.G. uhttps://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2486.2008.01769.x