McMurdo Dry Valleys: A Cold Desert Ecosystem

麦克默多干谷的极端环境将是位于南极洲麦克默多站以西约100公里的长期生态研究(LTER)项目的重点。干旱的山谷是世界上最极端的沙漠之一。常年被冰覆盖的湖泊、短暂的溪流和山谷内的大片土壤都受到低温、非常有限的降水和盐分积累的影响。山谷中的生物系统相对简单，没有维管植物或脊椎动物，昆虫也很少。营养相互作用和生物地球化学营养循环在很大程度上限于微生物种群和微型无脊椎动物。物种多样性和丰富度很低，这在这样的极端环境中是可以预测的。尽管这样简单，但在湖泊、溪流和土壤中，物种之间以及生物和物理化学环境之间存在复杂的相互作用。此外，生态系统各组成部分之间的相互作用提高了干旱河谷景观的整体生产力。所有的生态系统都不同程度地受到气候和物质运输的影响，但这一点在干燥的山谷中表现得最为明显。极端环境的明显影响，加上生态系统结构的普遍简单性，使干旱山谷成为研究这些基本关系的理想地点。两个中心假设将是本研究的重点：1)干旱河谷生态系统的结构和功能主要受物质限制，2)干旱河谷生态系统的结构和功能受物质输送的影响。干谷LTER将通过系统的环境数据收集、长期实验和模型开发计划，解决这些假设和LTER研究重点的五个核心领域。努力的重点将是整合组成麦克默多干谷景观的湖泊、溪流和陆地生态系统内部的生物过程以及它们之间的物质运输。

The extreme environment of the McMurdo Dry Valleys will be the focus of a Long Term Ecological Research (LTER) project located approximately 100 km west of McMurdo Station, Antarctica. The dry valleys are among the most extreme deserts in the world. The perennially ice-covered lakes, ephemeral streams, and extensive areas of soil within the valleys are subject to low temperatures, very limited precipitation, and salt accumulation. The biological systems in the valleys are relatively simple, with no vascular plants or vertebrates and very few insects. Trophic interactions and biogeochemical nutrient cycles are largely limited to microbial populations and micro-invertebrates. Species diversity and abundance are low as would be predicted for such extreme environments. Despite this simplicity, complex interactions among species and between the biological and physico-chemical environment exist in the lakes, streams and soils. Furthermore, interactions between various components of the ecosystem enhance the overall productivity of the dry valley landscapes. All ecosystems are shaped to varying degrees by climate and material transport, but nowhere is this more apparent than in the dry valleys. The obvious effects of an extreme environment coupled with the general simplicity of ecosystem structure makes the dry valleys an ideal location to study these basic relationships. Two central hypotheses will be the focus of this research: 1) The structure and function of dry valley ecosystems are primarily controlled by physical constraints, and 2) The structure and function of dry valley ecosystems are modified by material transport. The dry valley LTER will address these hypotheses and the five core areas of LTER research emphasis through a program of systematic environmental data collection, long-term experiments, and model development. Efforts will focus on the integration of the biological processes within and material transport between the lakes, streams and terrestrial ecosystems comprising the McMurdo Dry Valley landscape.