EAGER: Secondary foundation species as drivers of ecosystem resilience

基础物种，如珊瑚、海带和针叶树，是主导的、形成结构的生物，往往是管理的重点，因为它们对生态系统中所有其他植物和动物施加强大的控制，并调节生态系统服务。次生基础物种依赖于基础物种，通过进一步影响生物多样性和小气候，可以帮助维持比单独基础物种更高水平的生物生产力、化学平衡和其他生态系统功能。理论预测，支持高度生物多样性和功能的生态系统，如由基础和次级基础物种构成的生态系统，应该特别能适应环境压力，如干旱、高温和疾病爆发，否则这些压力可能会导致生态系统崩溃。这个项目使用乔治亚州海岸的盐沼作为生态系统模型来测试这些理论。这些沼泽是由一个基础物种构成的，网草，有肋贻贝集群作为次要基础物种。将在实际的沼泽中进行一项实验，以帮助确定在网草中重叠的贻贝是否能增强对干旱和蜗牛放牧的抵抗力或从干旱和蜗牛放牧中恢复过来，这两种压力在过去的20年里共同作用，杀死了超过25万英亩的网草。来自佛罗里达大学的一名博士生和两名本科生将参与这个项目。研究人员将参与幼儿园至五年级女生的课外暑期项目、七至八年级女生的春假项目和公立学校科学教师项目。研究结果还将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利益。在18个月的时间里，研究人员将使用防雨防潮结构和蜗牛笼来控制干旱和蜗牛放牧，在含有0、40或80个贻贝聚集的样地，以验证他们的假设，即随着贻贝数量的增加，8种不同的生态系统功能和2种盐沼多功能指数对这些压力源的抵抗水平和恢复速度也会增加。此外，他们将在从佛罗里达州到北卡罗来纳州分布的地点测量五种大小不同的相同生态系统功能，以调查贻贝是否增强了该地区对环境压力自然波动的恢复能力。通过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，该项目将揭示次生基础物种调节恢复力的生态和生物地球化学机制，并确定在盐沼景观中，较大的群落是否比较小的群落提供更多的保护，以抵御这些压力源。因此，这项实验和调查将提供关键信息，以评估基础和次级基础物种之间的等级相互作用是否应纳入我们对调节生物多样性、生态系统功能和恢复力的概念性理解。

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.