Intraspecific Variation in Ecophysiology of Three Dominant Prairie Grasses Used in Restoration: Cultivar Versus Non-Cultivar Population Sources

Dominant species play crucial roles in determining plant community structure and ecosystem function. Cultivars of the dominant prairie grasses are widely used in prairie restoration and are selected for characters such as high biomass production, increased reproductive output, and stress tolerance. Genetic differences exist between cultivar and non-cultivar population sources of dominant tallgrass prairie species, which may have implications for plant performance in prairie restoration. We measured net photosynthesis (A(net)), stomatal conductance (g(s)), and water use efficiency (WUE) in cultivar and non-cultivar dominant tallgrass prairie species Andropogon gerardii Vitman, Sorghastrum nutans (L.) Nash, and Schizachyrium scoparium (Michx.) Nash in both a greenhouse experiment and an experimental tallgrass prairie restoration. We found indicators of enhanced physiological performance (higher A(net,) g(s,) and/or WUE) in cultivar population sources of all three dominant grass species relative to non-cultivars. For A. gerardii, cultivars exhibited higher A(net) and WUE than non-cultivars. For S. nutans, cultivars exhibited higher g(s,) whereas non-cultivars showed higher WUE. Lastly, cultivars of S. scoparium showed higher WUE than non-cultivar population sources. Our results show that population selection of dominant species in restoration can have consequences for plant performance, which may have implications for competitive interactions that affect community structure (i.e. diversity) and ecosystem function (i.e. aboveground net primary production) during the reassembly of prairie systems.