8. Temperature Dependence of Carbon Dioxide, Nitrous Oxide and Methane Exchange in High Arctic Mineral Soils: Implications for Feedbacks to a Warming

Abstract

Plant communities in the high Arctic are distributed according to moisture gradients. If moisture regimes change in response to future climate change, the distribution of plant communities is also likely to change. An understanding of how interactions between vegetation community type and changes in temperature and moisture levels will impact the flux of nitrous oxide, methane and carbon dioxide in arctic soils is critical for predicting potential positive feedback to climate warming. My research quantifies the flux of these greenhouse gases from mineral soils collected from three different plant community types at Cape Bounty, Nunavut: wet sedge, mesic heath, and polar desert. Intact soil cores (0‐10 cm) were collected during July of 2008, then sealed and refrigerated for transportation back to Kingston. The cores were incubated at 4°C, 8°C, and 12°C, including a three week pre‐incubation to ensure the cores were completely equilibrated to their respective temperature. My results suggest a significant temperature dependency for production of each of the greenhouse gases, with enhanced output in the characteristically wetter sites. The response to temperature (Q10) does not; however, appear to be consistent across the different plant communities. Further field studies were conducted to determine the impact of these vegetative community types on observed soil temperature. My results demonstrate a tendency toward warmer temperatures and enhanced diurnal fluctuations at drier sites. These initial results suggest that in a warmer climate, high Arctic soils have the potential to contribute to a positive feedback to climate change through the efflux of these gases.29