9813061 LYONS 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.
