Collaborative Research: Do ecological feedbacks across trophic levels affect alternate stable states and restoration of tropical forests?

合作研究：跨营养级的生态反馈是否会影响热带森林的交替稳定状态和恢复？

• 批准号: 1557177
• 负责人: Thomas Dudley
• 金额: $ 78.06万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-15 至 2022-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1557177&HistoricalAwards=false
• 关键词: Collaborative; Research; Do; ecological; feedbacks

A substantial portion of the Earth's wildlands have been degraded by past land use, species extinctions and invasion by non-native species. Degraded ecosystems often do not provide the same important services to humans as intact systems - including such services as erosion prevention, flood control, and support for wildlife. This research addresses tropical forest ecosystems that have been degraded by past forest clearing and the loss of native fruit-dispersing birds and asks why these forests are not returning to native species dominance despite the cessation of the original disturbances that caused their degradation. It evaluates the interacting roles of widespread invasive pasture grasses, high levels of soil nitrogen, and loss of important native species (birds, a previously dominant native tree, and soil microorganisms) in stalling forest recovery. The work also addresses why the common restoration method of mass replanting of a single native tree species does not lead to recovery of native tropical forest. This research will provide badly needed information on growth requirements for endemic Hawaiian forest species and will help direct restoration actions to insure better success in recreating diverse native forests, which may result in cost savings for future restoration projects. This project will also train local students who will become the future stewards of these ecosystems.Insight into the theory of alternative stable states, which has come to dominate discussions of ecosystem degradation and restoration, will be gained with this research. A key assumption of this theory is that current conditions create feedbacks or priority effects that stall change, thus hindering recovery of ecosystems that exist in a degraded state. Most research on this topic focuses on the role of particular individual feedbacks in slowing ecosystem change. Using degraded montane tropical forests in Hawaii as a study system, this research addresses the role of multiple feedbacks, including cross-trophic level ones, in interfering with, or conversely allowing, community development away from a seemingly non-transient degraded state. An interdisciplinary team will address the importance and interactions of avian seed dispersal, overstory tree composition, understory grass competition with dispersing seedlings, and plant-soil and mycorrhizal feedbacks in maintaining persistent degraded conditions. The research tests specific interactions between birds, plants, nitrogen availability and mycorrhizae using manipulative field experiments, greenhouse feedback studies and ecological modeling. Together the team will work to determine what combinations of management actions are needed to accelerate ecosystem change in the direction desired by land managers.

由于过去的土地利用、物种灭绝和非本地物种的入侵，地球上很大一部分荒地已经退化。退化的生态系统通常无法为人类提供与完整系统相同的重要服务，包括预防侵蚀、防洪和支持野生动物等服务。这项研究涉及因过去的森林砍伐和本地水果传播鸟类的消失而退化的热带森林生态系统，并询问为什么尽管导致森林退化的原始干扰已经停止，但这些森林却没有恢复本地物种的优势。 它评估了广泛入侵的牧草、高水平的土壤氮以及重要本土物种（鸟类、以前占主导地位的本土树木和土壤微生物）的丧失在森林恢复停滞中的相互作用。这项工作还解释了为什么大规模重新种植单一本地树种的常见恢复方法无法导致本地热带森林的恢复。这项研究将提供有关夏威夷特有森林物种生长要求的急需信息，并将有助于指导恢复行动，以确保在重建多样化的原生森林方面取得更大成功，这可能会为未来的恢复项目节省成本。该项目还将培训当地学生，他们将成为这些生态系统的未来管理者。通过这项研究，我们将深入了解替代稳定状态理论，该理论已成为生态系统退化和恢复讨论的主导。该理论的一个关键假设是，当前条件会产生阻碍变化的反馈或优先效应，从而阻碍处于退化状态的生态系统的恢复。关于这个主题的大多数研究都集中在特定个体反馈在减缓生态系统变化中的作用。这项研究使用夏威夷退化的山地热带森林作为研究系统，探讨了多重反馈（包括跨营养级反馈）在干扰或相反允许社区发展远离看似非暂时的退化状态方面的作用。一个跨学科团队将研究鸟类种子传播、上层树木组成、林下草与传播幼苗的竞争以及植物-土壤和菌根反馈在维持持续退化条件中的重要性和相互作用。该研究利用操作性田间实验、温室反馈研究和生态模型来测试鸟类、植物、氮可用性和菌根之间的特定相互作用。该团队将共同努力确定需要采取哪些管理行动组合，以加速生态系统朝着土地管理者期望的方向变化。