Temperature Sensitivity of Methane Production in the Permafrost Active Layer at Stordalen, Sweden: a Comparison with Non-permafrost Northern Wetlands

Relationships were determined between methane (CH4) production and in situ conditions within the permafrost active layer during a single melt season at Stordalen, Sweden, with a specific emphasis on temperature sensitivity of methanogenesis. In situ temperature, moisture, pH, dissolved organic carbon, and CH4 concentration data were measured at three contrasting active layer sites (sedge mire, Sphagnum mire, and ombrotrophic bog), and laboratory incubations of active layer material were subsequently employed to determine the sensitivity of CH4 production to temperature. Q(10) values, describing the CH4 production response of peat to a temperature change of 10 degrees C, ranged from 1.9 to 3.5 and 2.4 to 5.8 for the sedge and Sphagnum mire sites, respectively. A wider review of the literature on Q(10) responses of methanogenesis in northern peatlands shows similar features to the temperature response of CH4 production in the active layer at Stordalen. In general, Q(10) to values are not significantly different in Arctic permafrost wetlands than non-Arctic northern wetlands; however, Sphagnum sites display Q(10) responses (mean Q(10) = 8) that are notably greater than that of wetter minerotrophic-sedge environments (mean Q(10) = 4.3). This finding has implications for the parameterization of Q(10) factors in numerical carbon cycling models, and suggests that the use of spatially variable Q(10) values could be a useful approach for more accurate modeling of CH4 fluxes front northern wetlands under different climatic change scenarios.