Development of biofuel feedstock presents opportunities for sustainable energy and energy independence, and also challenges for sustainable land-use and biodiversity maintenance. Perennial grasses, although promising sources of biofuel, present traits that mirror those of invasive species. Among the species being considered, Miscanthus spp. are promising biofuel feedstock candidates; however horticultural varieties in this genus have established feral and sometimes weedy populations, which heightens concern about the environmental impact of Miscanthus cultivation. We present results from an experiment that measured the relative performance of Miscanthusbiotypes at three levels of competition and at two locations within its targeted range of cultivation.
A two-year, factorially designed, garden experiment measured the effects of biotype, competitor species, and site location on the growth and reproductive performance of five biotypes of Miscanthus spp. These included three feral populations, one horticultural biotype, and seeded M. x giganteus(Powercane). The experiment was replicated in Columbus, Ohio and Ames, Iowa. Response variables were dry biomass, number of shoots, basal area, and number of seeds produced.
Experimental location generated distinct responses of focal biotypes. Miscanthus suffered severe mortality in Iowa during the second year of the experiment, precluding further analyses of treatments. In Ohio, biotypes and competitition influenced dry biomass and number of shoots at p<0.01, and basal area and seed production at p<0.001. Competition influenced dry biomass, number of shoots and basal area at p<0.001, and number of seeds at p=0.05. There was no significnat interaction between biotype and competition.
Of the biotypes analyzed, seeded M. x giganteus outperformed congeners in all measures except seed production. Although competition reduced performance of all focal biotypes, these results, together with the feral origin of three of our biotypes, suggest that competition may not limit population persistence of escaped Miscanthus. Given the superior growth responses of seeded M. x giganteus compared to feral and horticultural biotypes, our findings suggest that volunteer populations of this cultivar may become invasive within portions of the targeted region of cultivation.