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-degrees-45'N). Emissions from wet meadow tundra averaged 144 +/- 31 mg CH4/m2/d and ranged from 15.6 to 426 mg CH4/m2/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 CH4/m2/d. Consumption of ambient levels of methane was sporadically measured at these drier sites, and emissions ranged between -2.1 and 18.1 mg CH4/m2/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 CH4/m2/d. Calculated diffusive fluxes from open water varied with lake size, the large lakes emitting 3.8 mg CH4/m2/d and small lakes emitting an average of 77 mg CH4/m2/d. An updated estimate of global emissions from tundra indicates an annual flux of approximately 11 +/- 3 Tg CH4.