Research Starter Grant: Potential Loss of Old Soil Carbon in Response to Permafrost Melting

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Large pools of soil C have accumulated in high latitude ecosystems since glaciation as soil organic matter was climatically protected from decomposition by low temperatures and frozen soil. Air temperatures have been observed to increase at high latitudes over the last 25 years, and this "old" stored soil C may be susceptible to decomposition as soils thaw. Sustained and significant transfers of C to the atmosphere that could cause a positive feedback to climate change must come from stored soil C, which forms the bulk of the soil pool in these ecosystems. Therefore, understanding the sources of carbon respiration is critical to predicting the response of C cycling to climate change. The proposed research uses radiocarbon and stable isotope measurements of soil organic matter (SOM) and soil respiration to characterize the sources of soil C released following soil thaw. Organic and mineral soil cores collected from acidic and non-acidic tussock tundra sites at the Toolik Lake Long Term Ecological Research station will be studied to determine the potential of arctic soils to release old C as permafrost melts. This information is critical for predicting C loss from high latitude ecosystems to the atmosphere as a result of global change.