The McMurdo Dry Valleys are located on the western coast of McMurdo Sound (77°00'S 162°52'E) and form the largest relatively ice-free area (approximately 4800 square kilometers) on the Antarctic continent. These ice-free areas of Antarctica display a sharp contrast to most other ecosystems in the world, which exist under far more moderate environmental conditions. The perennially ice-covered lakes, ephemeral streams and extensive areas of exposed soil within the McMurdo Dry Valleys are subject to low temperatures, limited precipitation and salt accumulation. Thus, the dry valleys represent a region where life approaches its environmental limits, and is an "end-member" in the spectrum of environments included in the LTER Network. The dry valleys, unlike most other ecosystems, are dominated by microorganisms, mosses, lichens, and relatively few groups of invertebrates; higher forms of life are virtually non-existent. The overall objectives of the McMurdo LTER are to understand the influence of physical and biological constraints on the structure and function of dry valley ecosystems and to understand the modifying effects of material transport on these ecosystems. The McMurdo Dry Valley ecosystems are driven by the same basic processes, such as microbial utilization and re-mineralization of nutrients found in all ecosystems, but they lack many confounding variables, such as higher plants and animals, found in other ecosystems. McMurdo LTER research contributes to general ecological understanding through studies of processes that are readily resolved in these ecosystems. To successfully accomplish these studies, scientists must be present in the field--the McMurdo Dry Valleys. Samples and measurements cannot be obtained remotely and experiments must be conducted in situ if they are to have any relevance to the environment.
Why is it necessary to conduct long-term ecological research on the McMurdo Dry Valleys of Antarctica? To summarize from the McMurdo LTER Site Review Committee's January 1997 report, "the McMurdo LTER project is working on an incredible system for ecological study. It is not just a unique area, but more importantly, it exists at one end of the arid and cold spectra of terrestrial ecosystems." All ecosystems are dependent upon liquid water and shaped to varying degrees by climate and material transport, but nowhere is this more apparent than in the McMurdo Dry Valleys. In very few places on this planet are there environments where minor changes in climate so dramatically affect the capabilities of organisms to grow and reproduce. Indeed, the data being collected by the LTER indicate that the dry valleys are very sensitive to small variations in solar radiation and temperature and that this site may well be an important natural regional-scale laboratory for studying responses to human alterations of climate. While the Antarctic ice sheets respond to climate change on the order of thousands of years, the glaciers, streams and ice-covered lakes in the McMurdo Dry Valleys respond to change almost immediately. Thus, it is in the McMurdo Dry Valleys that the first effects of climate change in Antarctica should be observed.
(Photo courtesy Gayle Dana)
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