"Subsurface methane dynamics of fens: Biogeochemical controls on production, peat free-phase gas content and efflux"

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Peatlands are important ecosystems in Canada, covering approximately 12% of the country's landmass. These ecosystems play an important role in the global carbon cycle, accounting for up to one third of global soil carbon stock and up to 10% of atmospheric emissions of the greenhouse gas methane (CH4). Despite this important role, spatial and temporal patterns of CH4 fluxes from peatlands are still fairly poorly described, likely because of the contribution of ebullition (release of bubbles) to total CH4 flux. If ebullition is important, this also suggests that bubbles (free-phase gas; FPG) are present within peat soil. Research over the past decade has indicated the presence and importance of FPG in Sphagnum-dominated peatlands; however, very little is known about FPG in more mineral rich peatlands and the relative importance of ebullition to total CH4 flux from these ecosystems. These mineral rich peatlands, fens, have a different vegetation community, and hence soil structure, suggesting that the rate of CH4 production, transport and trapping of FPG may be very different than Sphagnum-dominated peatlands. The proposed research program aims to address this gap in knowledge by 1) determining the stock of CH4 dissolved, and as FPG in several fen peatlands, 2) describing the spatial and temporal variation in the size of this stock, 3) evaluating the importance of ebullition to the total CH4 flux from these fens, and 4) evaluating potential controls on CH4 stock and ebullition.