A methane ftux transect along the trans-Alaska pipeline haul road

Methane flux measurements were made during the summer of 1987 at 10 km intervals along a north—south transect from Prudhoe Bay (70°13’N) to the Arctic Circle (66°30’N) in Alaska. A regional comparison showed that the mean CH₄ flux from arctic tundra (52 mg m^-2 d^-1) was significantly greater than the mean from high latitude taiga (11 mg m^-2 d^-1). Sites occupied on the transect were classified into 6 categories based on differences in plant communities and CH₄ emission was further compared. Mean CH⁴ fluxes (mg m^-2 d^-1) for each category were: wet tundra, 90; low brush-muskeg bog, 45; moist tundra, 31; freshwater ponds, 21; spruce forest, 4.6; and alpine tundra, 0.6. Differences among means were statistically significant. During the period of observation, CH⁴ emission was only weakly correlated with soil temperature, water table depth, thaw depth and organic layer depth. Extending these fluxes to appropriate areas and emission periods yields independent estimates of annual CH₄ emission from global tundra and taiga environments of 38 Tg and 15 Tg. This is about 46% of the wetland emission term or 10% of the global atmospheric input.