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

是什么决定了物种分布的自然变化？一种理论认为，部分变化是由不同的稳定状态造成的。当不同的稳定状态存在时，不同的物种可能出现在看似相似的栖息地。然而，就提供的生态系统服务而言，一组物种往往比其他物种更可取。虽然已经提出了许多替代稳定状态的例子，但很少有实验能严格证明它们，使管理方法复杂化。有证据表明，湿地存在三种群落状态，以(1)漂浮植物、(2)淹没植物和(3)浮游植物为主。本项目将通过实验来测试不同营养水平下植物状态的稳定性和群落反应是否不同。在研究池塘的水密笼中，通过几种处理将漂浮的植物和营养物质添加到先前存在的水下植物群落中，并监测生态系统的反应。识别具有其他稳定状态的生态系统是至关重要的，因为状态之间可能发生灾难性的变化，而传统的管理实践无法解决这些变化。在湿地，本地和入侵的漂浮植物的爆发会减少动植物的生物多样性。这项研究将有助于确定这些暴发背后的机制，从而制定更好的控制战略并更好地了解其影响。该项目为本科生和高中生提供了教育机会，其结果将通过出版物和K-12外展活动传达给科学家和公众。

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.