McMurdo Dry Valleys LTER Overview

Background The McMurdo Dry Valleys LTER project is an interdisciplinary study of the aquatic and terrestrial ecosystems in a cold desert region of Antarctica. In 1992 this area was selected as a study site within the National Science Foundation's Long-term Ecological Research (LTER) Program. Details about the research can be reviewed through the original 1992 research proposal to the National Science Foundation, or the most recent 2016 proposal, resulting in funding for another 6 years.

The McMurdo LTER project is one of 28 sites comprising the LTER Network and is conducting long-term ecological research in a broad array of ecosystems. Each site within the LTER Network shares a common commitment to create a legacy of well-designed and well-documented long-term field experiments and observations for use by future generations to improve understanding of basic properties of ecosystems as well as factors causing widespread changes in the world's ecosystem. Sites are also required to synthesize research efforts, such as response to natural and anthropogenic disturbances, and to extrapolate from local scales to continental and global scales. 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 original objectives of the McMurdo LTER were 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. Now in the third funding cycle, we are poised to answer more complex questions about biodiversity, the impact of climatic legacies, and ecosystem structure and function. 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.

Activities The McMurdo Dry Valleys LTER project has successfully completed a field season every year (October-February) since 1993. During the 1993-94 season 18 scientists were deployed to McMurdo Station and Taylor Valley to conduct research associated with the LTER project. These scientists initiated core measurement programs to obtain baseline ecologically-relevant data from the atmosphere, glaciers, streams, soils, and lakes. Since then, about 25-30 scientests each season have participated.

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