DISSERTATION RESEARCH: Existence and controls of alternative stable states in pond producer communities

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What determines natural variation in the distribution of species? One theory suggests that part of the variation results from alternative stable states. When alternative stable states are present, different sets of species can occur in habitats that seem similar. However, one species set is often more desirable than others in terms of ecosystem services provided. While many examples of alternative stable states have been proposed, few experiments have rigorously demonstrated them, complicating management approaches. Evidence suggests three community states exist in wetlands, dominated by (1) floating plants, (2) submerged plants, and (3) phytoplankton. In this project, an experiment will be performed to test the stability of the plant states and whether the community response is different at different nutrient levels. In watertight cages in research ponds, floating plants and nutrients will be added to preexisting submerged plant communities in several treatments, and ecosystem responses will be monitored. It is crucial to identify ecosystems with alternative stable states, because catastrophic shifts between states can occur that traditional management practices do not address. In wetlands, native and invasive floating plant outbreaks can decrease plant and animal biodiversity. This research will help identify mechanisms behind these outbreaks, leading to better control strategies and a better understanding of their effects. This project incorporates educational opportunities for undergraduate and high school students, and its results will be communicated to scientists and the public through publications and K-12 outreach activities.