Methane emissions from tundra environments in the Yukon‐Kuskokwim delta, Alaska

Over a 6‐week period from July 3 to August 10, 1988, we made measurements of the flux of methane by enclosure techniques from major tundra environments in the Yukon‐Kuskokwim Delta of Alaska (60°45′N). Emissions from wet meadow tundra averaged 144 ± 31 mg CH 4 /m 2 /d and ranged from 15.6 to 426 mg CH 4 /m 2 /d, varying with soil moisture and temperature. Flux from the drier upland tundra was approximately 2 orders of magnitude lower and averaged 2.3 ± 1.1 mg CH 4 /m 2 /d. Consumption of ambient levels of methane was sporadically measured at these drier sites, and emissions ranged between −2.1 and 18.1 mg CH 4 /m 2 /d. Tundra lakes emit methane from the open water surface as well as from fringing aquatic vegetation. The presence of vegetation significantly enhanced flux over open water rates. Average fluxes from a variety of sites with vegetation ranged between 62.7 and 153.5 mg CH 4 /m 2 /d. Calculated diffusive fluxes from open water varied with lake size, the large lakes emitting 3.8 mg CH 4 /m 2 /d and small lakes emitting an average of 77 mg CH 4 /m 2 /d. An updated estimate of global emissions from tundra indicates an annual flux of approximately 11 ± 3 Tg CH 4 .