EAGER: Secondary foundation species as drivers of ecosystem resilience

基础物种，如珊瑚、海带和针叶树，是构成结构的优势生物体，通常是管理的重点，因为它们对生态系统中的所有其他动植物和生态系统服务的调节施加了强大的控制。次生基础物种依赖于基础物种，并通过进一步影响生物多样性和小气候，可以帮助维持生物生产力、化学平衡和其他生态系统功能，其水平高于基础物种单独维持的水平。理论预测，支持高度生物多样性和功能的生态系统，比如那些由基础物种和次要基础物种构建的生态系统，应该对干旱、高温和疾病爆发等环境压力特别有弹性，否则可能会导致生态系统崩溃。该项目使用佐治亚州海岸的盐沼作为模型生态系统来检验这些理论。这些沼泽是由基础物种线草构成的，次要基础物种是一簇簇有肋纹的贻贝。将在实际的沼泽中进行一项实验，以帮助确定线草中贻贝的重叠是否有助于提高对干旱和蜗牛觅食的抵抗力或恢复能力。过去20年里，这两种压力共同作用，导致超过25万英亩的线草死亡。佛罗里达大学的一名博士生将和两名本科生一起参与这个项目。调查人员将通过参加K-5女孩的课后暑期计划、7-8年级女孩的春假计划和公立学校的科学教师计划进行外联。研究结果还将被用于设计管理和保护生态系统的新方法，以优化多种基础物种的效益。在18个月的时间里，研究人员将使用雨潮排除结构和蜗牛笼子在包含0、40或80只贻贝的地块中控制干旱和蜗牛放牧，以检验他们的假设，即8种不同的生态系统功能和盐沼对这些应激源的多功能指数随着贻贝数量的增加而增加。此外，他们将在从佛罗里达州到北卡罗来纳州的不同地点测量五种相同的生态系统功能，以调查贻贝是否提高了该地区盐沼对环境压力自然波动的适应能力。在分析无脊椎动物群落、土壤条件、放牧强度和生态系统功能随时间的变化时，该项目将揭示这种次生基础物种可能调节复原力的生态和生物地球化学机制，并确定盐沼景观中较大的聚集体是否比较小的聚集体提供更多的保护，以抵御这些压力。因此，这项实验和调查将产生关键的信息，以评估基础物种和次要基础物种之间的等级相互作用是否应该纳入我们对调节生物多样性、生态系统功能和弹性的力量的概念理解中。

Foundation species, such as corals, kelp, and conifer trees, are dominant, structure-forming organisms that are often the focus of management because they exert powerful control over all other plants and animals in the ecosystem and the regulation of ecosystem services. Secondary foundation species are dependent on foundation species and by further affecting biodiversity and the microclimate can help maintain biological productivity, chemical balances, and other ecosystem functions at higher levels than those maintained by foundation species alone. Theory predicts that ecosystems that support high biodiversity and functioning, like those structured by foundation and secondary foundation species, should be especially resilient to environmental stresses, like droughts, heat spells and disease outbreaks, that might otherwise drive ecosystems to collapse. This project uses salt marshes on the Georgia coast as a model ecosystem to test these theories. These marshes are structured by a foundation species, cordgrass, with clusters of ribbed mussels as secondary foundation species. An experiment in actual marshes will be conducted to help determine whether an overlap of mussels within cordgrass increases resistance to or recovery from drought and grazing by snails, two stresses that have acted together to kill more than 250,000 acres of cordgrass here over the last twenty years. One PhD student from the University of Florida will participate in this project along with two undergraduate students. Outreach will be through participation of the investigator in an after-school summer program for K-5 girls, a spring-break program for 7-8th grade girls, and a public school science teachers program. The results will also be used for designing new approaches to managing and conserving ecosystems that optimize the benefits of multiple foundation species.Over 18 months, the researchers will use rain and tide exclusion structures and snail inclusion cages to manipulate drought and snail grazing in plots that contain aggregations of 0, 40 or 80 mussels to test their hypothesis that the level of resistance and rate of recovery of eight, distinct ecosystem functions and two indices of salt marsh multifunctionality to these stressors increase with increasing numbers of mussels. In addition, they will measure five of the same ecosystem functions in aggregations that vary in size at sites distributed from Florida to North Carolina to investigate if mussels enhance salt marsh resilience to natural fluctuations in environmental stress across this region. In analyzing changes in invertebrate communities, soil conditions, grazing intensity, and ecosystem functions over time, this project will expose the ecological and biogeochemical mechanisms by which this secondary foundation species may mediate resilience and to identify whether larger aggregations provide more protection against these stressors than smaller aggregations within salt marsh landscapes. As a result, this experiment and survey will produce information critical to evaluating if hierarchical interactions among foundation and secondary foundation species should be incorporated in our conceptual understanding of forces that regulate biodiversity, ecosystem functioning, and resilience.