Doctoral Dissertation Research: Assessing the impacts of Pleistocene megaherbivores on vegetation stability and resilience in the Arctic

博士论文研究：评估更新世巨型食草动物对北极植被稳定性和恢复力的影响

• 批准号: 2230019
• 负责人: Jacquelyn Gill
• 金额: $ 5.61万
• 依托单位: University of Maine
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-01-01 至 2024-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2230019&HistoricalAwards=false
• 关键词: Doctoral; Dissertation; Research; Assessing; impacts

Large herbivores play an important role in shaping modern-day Arctic ecosystems by promoting plant growth, diversity, and nutrient cycling. They may also buffer the effects of climate change on tundra ecosystems by reducing permafrost thaw and the expansion of shrubs. Until ~12,000 years ago, the Arctic was home to a diverse array of herbivores (woolly mammoths, bison, wild horses, caribou, and muskoxen) coexisting in an environment called “mammoth steppe.” It is thought that this environment was maintained by large herbivores, similar to modern African savannas. As a result, some have suggested that “rewilding” large herbivores could be a viable management strategy for the Arctic. However, we know little about how much these ecosystem properties rely on herbivore diversity because few high-latitude systems support multiple species in high numbers today. The fossil record provides a natural archive of how large herbivores and climate change influenced Arctic plant communities through time. This project builds on dissertation-level research examining a paleoecological record from Squirrel Lake, Alaska to understand the effect of prehistoric herbivore diversity on the long-term stability of Arctic ecosystems and identify the species that made up the ice age herbivore community. This project investigates the role of large herbivore diversity on Arctic ecosystem properties by creating a multi-proxy sediment record of the plant and animal diversity that surrounded Squirrel Lake (Kotzebue Sound, Alaska) in a period spanning from today to ~55,000 years before present. Sedimentary ancient DNA and density of radiocarbon dated animal remains will be used to investigate patterns of megaherbivore and plant diversity surrounding the lake through time. Proxies for vegetation, megaherbivore presence, and paleoclimates will inform the reconstruction of a chronology of megafaunal presence and environmental change. This dataset will be used to measure the effect of herbivore diversity on different components of ecosystem stability (resistance, resilience, recovery, and latitude), providing a quantitative framework to understand the impacts of these animals. This research will inform the current debate about herbivore reintroductions as a management tool for Arctic ecosystems and contribute data on the processes that shaped the mammoth steppe. The results of this study will be shared with local communities in the Kotzebue Sound area in a public, interactive exhibit, and used to build a virtual reality experience aimed at middle schoolers in Alaska and Maine.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.

大型食草动物通过促进植物生长、多样性和养分循环，在塑造现代北极生态系统方面发挥着重要作用。它们还可以通过减少永久冻土的融化和灌木的扩张来缓冲气候变化对苔原生态系统的影响。直到大约12,000年前，北极还是各种食草动物（长毛猛犸象、野牛、野马、驯鹿和麝牛）的家园，它们共存于一个被称为“猛犸草原”的环境中。据认为，这种环境是由大型食草动物维持的，类似于现代非洲的稀树草原。因此，一些人建议，“野化”大型食草动物可能是北极的一个可行的管理战略。然而，我们对这些生态系统特性在多大程度上依赖于食草动物多样性知之甚少，因为今天很少有高纬度系统支持大量的多物种。化石记录提供了一个自然档案，说明大型食草动物和气候变化如何影响北极植物群落。该项目建立在研究阿拉斯加松鼠湖的古生态记录的论文水平研究的基础上，以了解史前食草动物多样性对北极生态系统长期稳定性的影响，并确定组成冰河时代食草动物群落的物种。该项目调查了大型草食动物多样性对北极生态系统特性的作用，方法是创建一个多代理沉积物记录，记录松鼠湖（阿拉斯加州Kotzebue Sound）周围的植物和动物多样性，时间跨度从今天到距今约55，000年。沉积的古代DNA和放射性碳年代测定的动物遗骸的密度将被用来调查随着时间的推移，湖泊周围的大型食草动物和植物多样性的模式。植被，巨型食草动物的存在和古气候的代理将告知重建的巨型动物的存在和环境变化的年表。该数据集将用于测量食草动物多样性对生态系统稳定性不同组成部分（抗性，弹性，恢复和纬度）的影响，为了解这些动物的影响提供定量框架。这项研究将为目前关于将食草动物重新引入作为北极生态系统管理工具的辩论提供信息，并为形成猛犸草原的过程提供数据。这项研究的结果将在Kotzebue Sound地区的公共互动展览中与当地社区分享，并用于建立针对阿拉斯加和缅因州中学生的虚拟现实体验。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。