The Role of Resource Legacy on Contemporary Linkages Between Biodiversity and Ecosystem Processes in a Cold Desert Ecosystem: The McMurdo Dry Valley LTER Program

麦克默多干谷（MCM） LTER项目侧重于南极洲寒冷沙漠地区的水生和陆地生态系统。它位于麦克默多湾的西海岸，形成了非洲大陆上最大的相对无冰区，但仍然受制于极端的环境条件：常年被冰覆盖的湖泊、短暂的溪流、大面积的裸露土壤、有限的降水和盐积累。所有的生态系统都在某种程度上受到气候和物质运输的影响，但这一点在MCM尤为明显，那里的生命接近其环境极限，气候的细微变化对液态水的产生产生重大影响。这反过来又产生了一系列影响生物繁殖、生产力、生物多样性和生物地球化学的过程。研究表明，干谷生态系统对太阳辐射和温度的微小变化非常敏感，因此，南极冰盖对气候变化的反应是几千年，而这里的冰川、溪流和冰雪覆盖的湖泊几乎是立即做出反应。MCM的总体目标是了解1)物理和生物限制对干谷生态系统结构和功能的影响，2)物质运输对这些生态系统的修正作用。MCM研究的最新阶段调查了过去气候变化的遗产仍然强烈地覆盖了当前的生态条件。这个新阶段将探讨资源遗产和现存过程在决定当代生物多样性和生态系统过程中的作用。假设将通过持续监测和实验项目的结合以及在一个旨在整合和综合景观尺度数据的有力建模组件中的新研究来进行测试。新的活动将使生物多样性问题能够以更明确的方式得到解决，特别是物理分散和生境适宜性之间的相互作用，并将继续努力集中于综合研究地点的水生和陆地组成部分的生物过程。化学计量学和分子多样性成分将被纳入生物地球化学研究，通过对景观尺度元素转化和遗传变异的记录，提供一种整合所有生态系统成分的共同货币。更广泛的影响包括研究生和本科生的培养、公共教育和国际合作。外展活动包括校园LTER方案、教师体验南极洲、向达官贵人和其他实地访问者作科学报告，以及通过科学文献和非专业媒体继续传播成果。

The McMurdo Dry Valleys (MCM) LTER project focuses on aquatic and terrestrial ecosystems in a cold desert region of Antarctica. Located on the western coast of McMurdo Sound it forms the largest relatively ice-free area on the continent yet is still subject to extreme environmental conditions: perennially ice-covered lakes, ephemeral streams, extensive areas of exposed soil, limited precipitation, and salt accumulation. All ecosystems are in some way shaped by climate and material transport yet nowhere is this more apparent than at MCM, where life approaches its environmental limits and subtle changes in climate have a major influence on the generation of liquid water. This in turn produces a cascade of processes influencing biological reproduction, productivity, biodiversity, and biogeochemistry. Research has shown that the Dry Valleys ecosystems are very sensitive to small variations in solar radiation and temperature so, while Antarctic ice sheets respond to climate change on the order of thousands of years, the glaciers, streams, and ice-covered lakes here respond almost immediately. The overall objectives of MCM are to understand 1) the influence of physical and biological constraints on the structure and function of Dry Valleys ecosystems and 2) the modifying effects of material transport on these ecosystems. The most recent stage of MCM research investigated the legacy of past climate change still strongly overprinting present ecological conditions. This new stage will explore the role of resource legacy and extant processes on determining contemporary biodiversity and ecosystem processes. Hypotheses will be tested through a combination of on-going monitoring and experimental programs plus new research within a vigorous modeling component designed to integrate and synthesize the data on a landscape scale. The new activities will enable biodiversity issues to be addressed in a more definitive manner, especially the interplay between physical dispersion and habitat suitability, and efforts will continue to focus on the integration of the biological processes in both aquatic and terrestrial components of the study site. Stoichiometric and molecular diversity components will be incorporated into the biogeochemistry research to provide a common currency integrating all ecosystem components through the documentation of landscape scale elemental transformations and genetic variation. The broader impacts include the training of graduate and undergraduate students, public education, and international cooperation. Outreach activities include the Schoolyard LTER program, Teachers Experiencing Antarctica, scientific presentations to dignitaries and other visitors to the field site, and the continued dissemination of results in scientific literature and through the lay media.