Homogenization of the Earth's biota is affecting nearly every region on Earth, and many introduced species are having negative economic impacts. Grasslands contain perhaps the most homogenized communities in the world, yet we have a relatively poor understanding of how exotic species are impacting species diversity. This project will address this knowledge gap by comparing species diversity between communities containing all exotic or all native species under controlled field conditions to test hypotheses for how species diversity is maintained and how it might respond to changes in rainfall patterns. Two specific hypotheses are being tested: 1) exotic species are causing a decline in species diversity, and 2) exotic assemblages are characterized by highly productive species that increase in dominance, whereas native assemblages are characterized by species having more even and complete resource use across space and time.
Grasslands may become increasingly important to the U.S. economy as producers of biomass for forage and biofuels, and results from this work will be useful to managers who are attempting to establish or maintain diverse plant mixtures. Results will be disseminated broadly to enhance scientific and technological understanding through publications, presentations at meetings, and educational and extension projects. The work will also help to train the next generation of scientists.
