EAGER: The role of demographic stochasticity in community assembly

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One of the great puzzles in ecology is explaining how similar species can coexist in a community; presumably, one species should be a better competitor and cause extinction of all similar species. Plant coexistence is especially difficult to explain, because plants share a relatively small number of limiting resources, which should greatly restrict the number of species that can coexist. So, how it is possible for some plant communities to have hundreds of coexisting species? At least two factors, in addition to the number of limiting resources, might promote coexistence: conditions such as soil nutrient availability might vary within a community (environmental heterogeneity) and individual plants might have different rates of germination and death due to random chance (demographic stochasticity). Dr. Burns and her collaborators will conduct a novel experiment at Case Western Reserve University to ask: what is the relative importance of environmental heterogeneity and demographic stochasticity in creating conditions that allow for many species of plants to coexist? The proposed experiment will manipulate heterogeneity of the soil environment and introduce species into populations belonging to the same species and a closely related species. This experiment will be able to clearly distinguish for the first time the relative importance of environmental heterogeneity and demographic stochasticity in determining which species can be found together in a particular community.Dr. Burns and her collaborators work closely with a local government organization, Cleveland Metroparks, to answer important local management questions and ensure open communication between scientists and land managers. Cleveland Metroparks is an ~8000 ha series of parks that ring the greater Cleveland area. The Cleveland Metroparks Natural Resources Division is committed to maintaining the health and diversity of the parks. Maintaining plant community diversity is essential for Metropark's ability to provide essential ecosystem services, such as providing clean water to the Cleveland area. This project will enhance our understanding of coexistence, and will help managers prevent and control biological invasions and maintain plant community diversity. For example, if more heterogeneous sites are more likely to be invaded by pest species, managers can target those areas for monitoring to prevent new and potentially detrimental biological invasions.