Collaborative Research: Controls of ecosystem development during rapid environmental change: Yellowstone in the late-glacial and early-Holocene periods

晚更新世冰期高峰和早全新世热盛期（约21000 ~ 7000年前）之间是一个剧烈的环境变化和生物调整时期。冰川消融地区新生态系统的形成是由冰川消退的速度、冰川后气候变化的性质、新景观的特征以及生物殖民者的生活史特征所决定的。黄石地区形成了美国西部最大的独立冰原，17世纪后的冰川消退引发了一系列记录不佳的生物事件，最终导致了今天的陆地和水生生态系统。对黄石地区晚冰期和全新世早期的考察提出了以下问题：在新创造的景观中，陆地和水生生态系统发展的主要控制因素是什么？具体来说，在剧烈的气候变化期间，过去的生物群如何受到内在的生物限制、景观演变和次区域气候差异的影响？该研究通过检查来自以下地点的湖泊沉积物记录，验证了有关气候和非气候驱动因素在生态系统发展中的重要性的假设：(1)沿着冰消退的路径，(2)跨越各种基质，(3)位于夏季湿降水和夏季干降水地区。黄石公园是研究陆地和水生生态系统发展和结构的理想区域，因为：(1)从先前的数据综合和古气候模式模拟中可以很好地了解美国西部的气候历史；(2)黄石地区详实的冰川史为当地环境变化提供了独立信息；(3)不同的基质和降水制度塑造了现代生态系统的分布，在过去也可能如此；(4)以前的古生态学发现激发了更细致的研究问题，这些问题可以通过获得新的高分辨率记录来解决。研究的智力价值：了解气候变化对生物的影响是地球系统研究的一个主要挑战，并且在最近的国际和美国气候变化评估中被确定为高度优先事项。拟议的研究建立在对黄石公园过去的现有知识的基础上，以更好地了解陆地和水生生态系统对环境变化的适应能力，包括预测未来规模的突发气候事件。该项目采用分层采样方法，这在大多数古生物数据稀少的地方是不可能的，所获得的信息将有助于回答有关非生物和生物变量在调节气候变化对物种、群落和生态系统的影响中的重要性的基本生物学问题。由此产生的综合将是弥合当前对短时间尺度生态过程的理解与长时间尺度古生态数据中保存的巨大变化证据之间差距的关键一步。这项研究的更广泛影响在于，它有助于更好地向公众、土地和资源管理者以及学生介绍国家公园环境历史的重要性，包括对过去气候变化和生态系统敏感性的了解。特别是这个项目，以多种方式扩展了外展活动，其中包括由国家公园管理局定期更新有关黄石历史的网络传播信息；为公园工作人员提供有关古气候前沿研究的教育和培训活动；将黄石公园的发现纳入公园指导的K-12课程和大学课程；在科普杂志上发表；以及黄石公园新博物馆展览的内容。该项目还延续了pi的承诺，即培训和教育下一代多样化的科学家，并为建立多学科古气候数据集的持续努力做出贡献，供研究人员、土地管理者、教育工作者和公众使用。

The period between the late-Pleistocene glacial maximum and the early-Holocene thermal maximum (ca. 21,000 to 7,000 years ago) was a time of dramatic environmental change and biotic adjustments. The creation of new ecosystems in deglaciated regions was governed by the rate of ice recession, the nature of postglacial climate change, the characteristics of new landscapes, and the life-history traits of the biologic colonizers.The Yellowstone region supported the largest independent ice field in the western U.S., and ice recession after 17 cal ka set in motion a sequence of poorly-documented biologic events that ultimately led to the present-day terrestrial and aquatic ecosystems. This examination of the late-glacial and early-Holocene periods in the Yellowstone region poses the following questions: What are the primary controls of terrestrial and aquatic ecosystem development on newly created landscapes? Specifically, how are past biota influenced by intrinsic biological constraints, landscape evolution, and subregional climate differences during a period of dramatic climate change? The study tests hypotheses concerning the importance of climatic and nonclimatic drivers in ecosystem development through an examination of lake-sediment records from sites that (1) lie along the path of ice recession, (2) span a variety of substrates, and (3) are situated within summer-wet and summer-dry precipitation regimes.Yellowstone is an ideal region to examine the development and structuring of terrestrial and aquatic ecosystems, because (1) the climate history of the western US is reasonably well understood from prior data syntheses and paleoclimate model simulations; (2) a well-documented glacial history of the Yellowstone region offers independent information on local environmental change; (3) different substrates and precipitation regimes shape modern ecosystem distributions and likely have in the past as well; and (4) previous paleoecologic findings motivate more-nuanced research questions that can be addressed with the acquisition of new high-resolution records.Intellectual Merit of the Research: Understanding the biotic consequences of climatic change is a major challenge in Earth systems research and identified as a high priority in recent international and US climate change assessments. The proposed study builds on existing knowledge of Yellowstone's past in an effort to better understand the resilience of terrestrial and aquatic ecosystems to environmental change, including abrupt climate events of the magnitude projected in the future. This project adopts a stratified sampling approach that is not possible in most locations where paleobiotic data are sparse, and the information gained will help answer basic biologic questions about the importance of abiotic and biotic variables in modulating the effects of climate change on species, communities, and ecosystems. The resulting synthesis will be a critical step in bridging the gap between current understanding of ecological processes on short time scales and evidence of dramatic change preserved in paleoecologic data on long time scales.Broader Impacts of the Research lie in its contribution to ongoing efforts that better inform the public, land and resource managers, and students about the importance of environmental history in the national parks, including an understanding of past climate change and ecosystem sensitivity. This project in particular, extends outreach activities in a number of ways, among them regularly updated web-disseminated information by the National Park Service on Yellowstone's history; education and training activities for Park staff on cutting-edge paleoclimate research; incorporation of Yellowstone findings in Park-directed K-12 curricula and university coursework; publication in popular scientific magazines; and content for a new museum exhibit on Yellowstone. The project also continues the PIs' commitment to train and educate the next generation of diverse scientists and to contribute to ongoing efforts to build multidisciplinary paleoclimate datasets for use by researchers, land managers, educators, and the public.