Competitive effects of cultivar and wild switchgrass on other native grasses
There is mounting concern that selection and breeding of native grasses for greater biomass production could promote weediness. Yet little is known about the invasion potential or ecological impacts of such selectively bred native grasses. Here we focus on cultivars of native switchgrass (Panicum virgatum L.) that have undergone selection, breeding, and intraspecific hybridization to improve agronomic traits for biomass production. We evaluated the competitive effects of switchgrass cultivars (EG-2101 and ‘Trailblazer’) and wild switchgrass populations on two native prairie grasses [sideoats grama, Bouteloua curtipendula (Michx.) Torr., and Canada wild rye, Elymus canadensis L.] across a gradient of switchgrass density in a greenhouse. Cultivars produced 48–128% more biomass and reduced sideoats grama biomass by 25–59% more than wild switchgrass. Effects of switchgrass cultivars on Canada wild rye were minimal compared to sideoats grama. Later flowering and larger seed size of cultivars may be contributing to their greater biomass and competitive effects on sideoats grama. These data suggest that breeding switchgrass for enhanced biomass yield may increase competitive effects on some native grasses. Further studies are merited to test the potential for switchgrass biomass cultivars to spread and impact species diversity of restored and remnant native plant communities.
KeywordsBiofuel Heterospecific Interspecific Invasion Invasiveness
The authors thank University of Minnesota staff Kevin Betts, Roger Meissner, Rachel Pain, and Pamela Warnke for assistance and support in conducting the experiment; Matt Bickell for GIS support; Ellen Fuge (Minnesota Department of Natural Resources) and Meredith Cornett (The Nature Conservancy) for providing data from the Minnesota County Biological Survey as well as issuing the seed collection permit (2011-37R); and Brad Bolduan, Mark Cleveland, Larissa Mottl, and Russell Smith (Minnesota Department of Natural Resources) and Matt Graeve (The Nature Conservancy) for providing information on the management history of Scientific and Natural Areas. This project was funded by the University of Minnesota Undergraduate Research Opportunities Program (UROP) and the Minnesota Environment and Natural Resources Trust Fund.
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