Biological and landscape controls on the net greenhouse gas balance of High Arctic ecosystems

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Since the 1950's, annual air temperatures over Arctic landmasses have risen between 2C and 3C, while winter temperatures have increased as much as 4C. These warmer temperatures could induce cascading changes to terrestrial Arctic ecosystems, such as: altered hydrological cycles from increasing precipitation, shifting distribution of plant communities, altered surface properties such as decreased surface albedo, and increased permafrost thawing. Permafrost soils contain approximately half of the global soil carbon reservoir, so an increased rate of carbon loss due to permafrost thawing could accelerate future climate change. At the same time, permafrost thawing could liberate plant nutrients, increasing plant productivity and carbon storage, creating a negative feedback on future warming. To predict the future response of arctic ecosystems to changes in climate, we need to understand key greenhouse gas (GHG) cycling processes in high Arctic ecosystems at a range of spatial and temporal scales.*******At the Cape Bounty Arctic Watershed Observatory (CBAWO) on Melville Island, I will explore how the interactions between vegetation distribution and climate change alters the net GHG balance of high Arctic ecosystems. Specifically, I will examine 1) the contribution of mosses to net GHG fluxes, and the interaction between mosses and soil moisture 2) the contribution of polar semi-desert communities to the net methane balance of the high Arctic, and 3) how temperature, moisture, active layer depth, solar radiation, and satellite-based estimates of vegetation properties interact to control the net GHG balance across Arctic landscapes. I will explore these questions using a combination of field and laboratory measurements, including state-of-the-art automated chambers to measure carbon dioxide fluxes at high temporal frequencies and soil molecular techniques to characterize the bacteria responsible for methane production and consumption. My results, along with those of my colleagues working at this site, will be integrated into a state-of-the art watershed scale biogeochemistry model that will provide insights into how the region might change in the future in response to changes in climate. My research will help train the next generation of Arctic scientists by providing interdisciplinary training to 4 MSc, 1 PhD, and 5 undergraduate students - the training also provides key skills for many environmental positions. Results from my research will provide insights into how terrestrial ecosystems will respond to climate change, and help develop improved models that predict the contribution of Arctic ecosystems to future climate.******