02307nas a2200241   4500008004100000245010400041210006900145300001300214490000700227520153700234653002401771653002401795653002201819653001001841653001601851653002301867100002301890700001401913700001901927700002001946700001601966856008301982       2009                        eng d00aEcophysiological responses of two dominant grasses to altered temperature and precipitation regimes0 aEcophysiological responses of two dominant grasses to altered te  a400 -4080 v353 a<p>Ecosystem responses to climate change will largely be driven by responses of the dominant species. However, if co-dominant species have traits that lead them to differential responses, then predicting how ecosystem structure and function will be altered is more challenging. We assessed differences in response to climate change factors for the two dominant C4 grass species in tallgrass prairie, Andropogon gerardii and Sorghastrum nutans, by measuring changes in a suite of plant ecophysiological traits in response to experimentally elevated air temperatures and increased precipitation variability over two growing seasons. Maximum photosynthetic rates, stomatal conductance, water-use efficiency, chlorophyll fluorescence, and leaf water potential varied with leaf and canopy temperature as well as with volumetric soil water content (0&ndash;15 cm). Both species had similar responses to imposed changes in temperature and water availability, but when differences occurred, responses by A. gerardii were more closely linked with changes in air temperature whereas S. nutans was more sensitive to changes in water availability. Moreover, S. nutans was more responsive overall than A. gerardii to climate alterations. These results indicate both grass species are responsive to forecast changes in temperature and precipitation, but their differential sensitivity to temperature and water availability suggest that future population and community structure may vary based on the magnitude and scope of an altered climate.</p>10aAndropogon gerardii10aClimate variability10aLeaf gas exchange10aRaMPs10aSensitivity10aSorghastrum nutans1 aNippert, Jesse, B.1 aFay, P.A.1 aCarlisle, J.D.1 aKnapp, Alan, K.1 aSmith, M.D.  uhttps://www.sciencedirect.com/science/article/pii/S1146609X09000204?via%3Dihub