Physiology of dominant prairie grasses: The effect of population seed source on plant performance with implications for tallgrass prairie restorations

Cultivars of dominant C4 grasses, selected for characters such as high productivity and stress tolerance, are commonly used in tallgrass prairie restorations despite potential physiological dissimilarity to local seed sources. Since dominant species play crucial roles in community structure and ecosystem function, population source of dominant C4 grasses may have consequences for diversity, productivity, and ultimately success of grassland restorations. The objectives of this study were to test if intraspecific variation in physiology and productivity exists between cultivar and non-cultivar population sources of dominant prairie grasses (Andropogon gerardii, Sorghastrum nutans, and Schizachyrium scoparium) in both a greenhouse study and in an experimental prairie restoration (second year). Physiological characteristics including rates of net photosynthesis (Anet), stomatal conductance (gs), water use efficiency (WUE), and fluorescence (Fv/Fm) were measured in addition to primary production (i.e., ANPP). Cultivar population sources had equivalent or higher Anet, gs, WUE, Fv/F m, and ANPP than non-cultivars in both studies. A positive correlation between physiology (i.e., Anet) and primary productivity (i.e., ANPP) was found, indicating a link between physiological performance and ecosystem processes. This study was the first to experimentally test for intraspecific variation in physiology and productivity between cultivar and non-cultivar dominant prairie grasses in a common environment. It demonstrates equivalent or enhanced physiological performance and productivity in cultivars of dominant prairie grasses widely used in tallgrass prairie restorations. Therefore, population seed source should be considered as a potential filter on ecosystem re-assembly during restoration.