Submitted to: Botanical Society of America Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 4/12/2011
Publication Date: 7/9/2011
Citation: Matlaga, D.P., Davis, A.S., Quinn, L. 2011. Evaluating the invasive potential of Miscanthus biofeedstocks: Estimating population parameters for current and hypothetical candidate species. In: Botanical Society of America Proceedings. July 9-13, 2011, St. Louis, Missouri. Paper No. 79. Interpretive Summary:
Technical Abstract: Bioenergy crops have been promoted as environmentally friendly alternatives to petroleum, with widespread efforts underway to identify candidate species. However, many species under consideration share key traits (e.g. rapid growth, vegetative spread) with invasive species, creating concern that feedstock crops may escape cultivation and establish aggressive feral populations. In the North Central region of the USA, the C4 grass Miscanthus x giganteus (Mxg), a sterile Asian hybrid, is one of the top candidates for biomass production. In its current form Mxg is sterile but efforts are underway to restore fertility to this species. Our goal was threefold: 1) characterize the relationship between demographic performance and Mxg age; 2) use matrix projection models to understand the population trajectory for Mxg in its current form; 3) conduct simulations to understand how changes to recruitment parameters (seed fertility and rhizome fragmentation and establishment) will influence population trajectories. We collected demographic data from 13 experimental plantings of Mxg throughout Illinois which spanned a range of ages (1-7 years). Survival of Mxg is strongly age-dependent, with low survival in the first year after planting (~29%) and very high survival occurring after four years post-planting (> 92 %). A matrix projection model parameterized with fitted estimates of survival and seed production from our field data estimated a population growth rate (lambda) for Mxg of less than 1 (lambda = 0.929), indicating gradual population decline over the long-term. Simulations indicate that a growing population (lambda > 1) will occur if greater than one in 100,000 seeds can successfully establish or if adult plants produce greater than one rhizome fragment per every two individuals. Future efforts will incorporate the dispersal abilities of seeds and vegetative expansion of adult plants to parameterize models Mxg population spread.