Influence of Water Availability on Photosynthesis, Water Potential, Leaf δ13C, and Phenology in Dominant C4 Grasses In Kansas, USA

Determining effects of drought on prairie grasses could help us understand shifts in plant distributions and abundances with altered precipitation. The mixed grass prairie of North America is the zone where tallgrass prairies of the east intermingle with shortgrass prairies of the west. Species transitions in the mixed grass prairie reflect precipitation gradients, but little is known regarding how dominant grasses respond physiologically to water availability. We measured the performance of Andropogon gerardii, Bouteloua curtipendula, Schizachyrium scoparium, and Sorghastrum nutans in three precipitation treatments (ambient rainfall, drought, irrigated) in a southern mixed grass prairie near Hays, Kansas, USA. Photosynthesis and water potential were measured monthly in June and July of 2010 and 2011. Phenology and height measurements were collected semimonthly in June, July, and August of 2011. Growth increased under irrigated treatments in all four species. Conversely, leaf δ13C became lower in drought ...