Soil Biodiversity and Response to Climate Change: A Regional Comparison of Cape Hallett and Taylor Valley, Antarctica

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Soil ecosystems along the Antarctic Victoria Land coast from the McMurdo (MCM) Dry Valleys in the south (78-76 S) to Cape Hallett (72S) in the north occur across broad scale gradients of biodiversity, climate, and soil resource legacies (e.g. organic matter, nutrients, salts) from previous climates. The range of conditions encountered across this region can be used to test specific hypotheses derived from a soil biodiversity and habitat model developed from the findings of the MCM Dry Valleys Long-term Ecological Research Program (LTER). This "habitat suitability" model describes the distribution, abundance and diversity of soil biota based upon a combination of legacy and contemporary soil and climate properties. This current project will extend the habitat suitability model developed in the McMurdo Dry Valleys to the greater Victoria Land region at Cape Hallett. Insights into the relationship between biodiversity (microbes, invertebrates) and ecosystem functioning (soil respiration and nutrient cycling) may be especially important in the Victoria Land region since it encompasses a range of ecosystems, including those with organic matter near minimum detection limits and no invertebrates, to those with very high organic matter deposits and complex food webs (2-3 trophic groups comprised of 4 invertebrate taxa). A two-year study of field and laboratory research will address how soil food webs and ecosystem processes are affected by changes in climate, legacy and contemporary soil processes. This research will begin the regionalization of results and insights from the McMurdo LTER study and determine whether the changes in biodiversity along the range of soil habitats and landscape gradients in Taylor Valley, occur similarly across gradients in a richer, more complex habitats (e.g. Cape Hallett). This study involves international collaborations and will further multi-national research in the Antarctic. There is a clear and immediate need to understand how soil biodiversity and ecosystem functioning are related in all ecosystems and to determine the factors influencing the distribution of soil biodiversity across the Antarctic landscape. The motivation for the research proposed here underscores the value of soils and their biota in providing ecosystem services important to society (e.g., soil fertility). This is a difficult challenge as the taxonomic complexity of soil food webs elsewhere limits our ability to draw inferences about the functional significance of biodiversity and the responses of soil communities to varying soil conditions and climate. This research will make a significant contribution to testing biodiversity theory in all soils, because extension of and testing this conceptual model of soil biodiversity based on the simplest soil communities on earth will contribute to knowledge of complex temperate ecosystems. These linked studies of microbial and invertebrate diversity in relation to soil organic matter, moisture, and temperature change at Taylor Valley and Cape Hallett will provide one of the most complete quantitative assessments of soil diversity to date.