摘要：This study compares seasonal and spatial variations in methane fluxes as sources of uncertainty in regional CH4 flux upscaling from the wetlands of West Siberia. The study examined variability in summertime CH4 emissions from boreal peatlands, with a focus on two subtaiga fen sites in the southern part of West Siberia (Novosibirskaya oblast). We measured CH4 flux, water table depth, air and peat temperature, pH and electric conductivity of peat water during three field campaigns in summer 2011 (9–12 July, 26–28 July and 20–21 August). Fluxes were measured with static chambers at sites chosen to represent two of the most widespread types of wetlands for this climatic zone: soligenous poor fens and topogenous fens. In both sites the water table level acts as the primary control on fluxes. For the poor fen site with good drainage, water table controls CH4 fluxes on the seasonal scale but not on a local spatial scale; for the fen site with weak drainage and microtopographic relief, the water table controls fluxes on the local spatial scale, but does not drive seasonal variations in the flux magnitude. This difference in hydrology shows the necessity of including detailed wetland type classification schemes into large-scale modeling efforts. From these three measurement periods, we estimated the relative seasonal variation in CH4 emissions as 8% for the fen site and 26% for the poor fen site. These results were compared to estimates of other sources of uncertainty (such as interannual variation and spatial heterogeneity) to show that quantifying seasonal variability is less critical than these other variations for an improved estimate of regional CH4 fluxes. This research demonstrates and ranks the challenges in upscaling measured wetland CH4 fluxes across West Siberia and can guide future field campaigns.
