LTREB: Stability and resilience in the face of multiple interacting press and pulse disturbances of a changing world (Kenya Long-term Exclosure Experiment: KLEE)

人类赖以生存的生态系统不断受到各种力量的影响，包括家畜和野生食草动物、火灾、干旱和气候变化。例如，虽然越来越清楚的是，本地动物的丧失会对生态系统产生深远的影响，但关于大型哺乳动物的丧失或不同组合的增加对生态系统的影响的实验研究仍然很少。当我们开始了解生态系统在面对诸如食草动物放牧、干旱和火灾等个体力量时是如何（或不）具有弹性的，这个长期实验项目将寻求理解多种力量之间的相互作用，这些力量可能是复杂的，而且往往是意想不到的。这项在热带稀树草原的研究还将记录牲畜与本地动植物之间的相互作用，这将为世界上大多数野生动物与牲畜生产共享土地的混合用途景观的管理提供信息。在面对环境变化的情况下，扩大我们对生态系统恢复力的理解需要长期数据来检查多个相互作用的驱动因素。肯尼亚长期封闭实验（KLEE）使用半透性屏障创造了6种不同的组合：1)牛，2)斑马和羚羊，3)大象和长颈鹿，同时控制燃烧，并跨越多个干旱周期。利用和扩展超过25年的数据，肯尼亚长期封闭实验将提出以下问题：1)几十年来，在多种实验和自然压力下，这一稀树草原生态系统的稳定性和恢复力是如何变化的？2)生态系统对压力源是否有一个可识别的结构（如层次结构）？虽然一些研究已经检查了这些问题的各个方面，但研究团队处于一个独特的位置，可以在长期和生态相关的时期内解决这些问题，并有多个实验驱动因素。尽管已有研究表明，多种压力源协同作用导致生态系统达到无法恢复的阈值，但该系统的长期数据已经开始表明，交互机制可以缓冲生态系统。了解多种环境压力源之间的相互作用是理解生态系统恢复能力的必要条件。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The ecosystems upon which humans depend are continually affected by a wide variety of forces, including domestic and wild herbivores, fire, drought, and climate change. For example, although it is becoming increasingly clear that loss of native animals can have far-reaching effects on ecosystems, experimental studies on the effects of loss or addition of different combinations of large mammals on ecosystems remain rare. While we are beginning to understand how ecosystems are (or are not) resilient in the face of individual forces such as grazing by herbivores, drought, and fire, this long-term experimental project will seek to understand the interactions amongst multiple forces that are likely to be complex and often unexpected. This research in a savanna rangeland will also document the interactions between livestock and native plants and animals that will inform the management of mixed-use landscapes in a world where most wildlife shares land with livestock production. Extending our understanding of ecosystem resilience in the face of environmental variability requires long-term data examining multiple interacting drivers. The Kenya Long-term Exclosure Experiment (KLEE) uses semi-permeable barriers to create six different combinations of 1) cattle, 2) zebras and antelopes, and 3) elephants and giraffes, along with controlled burns, and across multiple drought cycles. Leveraging and extending more than 25 years of data, the Kenya Long-term Exclosure Experiment will ask: 1) how does the stability and resilience of this savanna ecosystem change under multiple experimental and natural stressors over multiple decades?, and 2) is there a discernable structure (e.g., hierarchy) of stressors to which the ecosystem responds? While some studies have examined aspects of these questions, the research team is in a unique position to address them across long and ecologically relevant periods of time, and with multiple experimental drivers. Although it has been suggested that multiple stressors synergistically lead to ecosystem thresholds from which recovery is not possible, the long-term data from this system has begun to suggest interactive mechanisms that buffer the ecosystem. Understanding interactive effects between multiple environmental stressors is integral to understanding ecosystem resilience.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.