Controls on atmospheric exchanges of carbon dioxide and methane for a variety of arctic tundra types

This study examined fluxes and subsurface concentrations of carbon dioxide (CO2) and methane (CH4) for six different vegetation community plots during the 2008 growing season at Daring Lake, N.W.T. The objectives of this study were: 1) to assess the temporal and spatial variability of CO2 and CH4 flux within different arctic tundra ecosystems and 2) to quantify and understand the mechanisms that control CO2 and CH4 flux. Hydrology was an important driver of CO2 and CH4 exchange among vegetation communities. High spatial variability in CH4 exchange in wet sites was found due to the position of the water relative to microtopography. Major differences were found between subsurface gas dynamics in mineral and peat soils. Sedge and fen tussock and hollow sites displayed much higher heterogeneity among profiles than the heath and shrub sites. Controls on subsurface production, oxidation and transport contributed to the surface-atmosphere flux of CO 2 and CH4.