Temporal variation in methane emission from tundra wetlands in a permafrost area, northeastern Siberia

Abstract

Summer variations in net methane flux and environmental variables were investigated in a Siberian permafrost area during the summers of 1993 and 1995. In each region, the measurements were made at two fixed sites: waterlogged wetlands and relatively dry grasslands. Methane flux from the waterlogged site at Tiksi (71.5°N, 130.0°E) averaged 46.3 mg CH 4 m −2 d −1. Flux from the waterlogged site at Chersky (68.5°N, 161.4°E) was approximately one order of magnitude greater than that at Tiksi and averaged 281.1 mg CH 4 m −2 d −1. Fluxes from the relatively dry sites were near zero and frequently negative in both regions. The emissions from the waterlogged sites showed diurnal and intraseasonal variation, while no significant variation in flux was observed at the dry sites. Our results suggest that temporal variation in methane flux from waterlogged sites in permafrost areas was controlled by the thermal regime of a seasonal thaw layer. The diurnal variation in the flux was correlated with ground temperature at a depth of 10–30 cm. For summer-season variation, the correlation between flux and centimeter–degrees, which is the product of ground temperature and thaw depth, was quite strong. The parameter, centimeter–degrees, is expected to be a good predictive indicator of methane emission from wetlands in permafrost areas.