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LTER项目的重点是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，形成了大陆上最大的相对无冰区，但仍然受到极端环境条件的影响：常年冰封的湖泊，短暂的溪流，大面积裸露的土壤，有限的降水和盐的积累。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，但没有任何地方比MCM更明显，在那里，生命接近其环境极限，气候的微妙变化对液态水的产生有重大影响。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，虽然南极冰盖对气候变化的反应大约是数千年，但这里的冰川，溪流和冰封的湖泊几乎立即做出反应。MCM的总体目标是了解1）物理和生物约束对干旱河谷生态系统结构和功能的影响，以及2）物质运输对这些生态系统的改变作用。 MCM研究的最新阶段调查了过去气候变化的遗留问题，这些问题仍然强烈地影响着目前的生态条件。这一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方面的作用。假设将通过一个正在进行的监测和实验计划，加上新的研究，旨在整合和综合景观尺度上的数据在一个充满活力的建模组件的组合进行测试。新的活动将使生物多样性问题能够得到更明确的解决，特别是物理分散和生境适宜性之间的相互作用，并将继续努力把重点放在研究地点水生和陆地部分的生物过程的整合上。化学计量和分子多样性组成部分将纳入生态系统地球化学研究，通过记录地貌尺度的元素变化和遗传变异，提供一种综合所有生态系统组成部分的共同货币。更广泛的影响包括研究生和本科生的培训，公共教育和国际合作。外联活动包括校园LTER方案、教师体验南极洲、向贵宾和其他实地访问者作科学介绍，以及继续在科学文献中和通过非专业媒体传播成果。

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.