THE EFFECT OF SOIL-MOISTURE AND THAW DEPTH ON CH4 FLUX FROM WET COASTAL TUNDRA ECOSYSTEMS ON THE NORTH SLOPE OF ALASKA

Results from a 2-year study of wet coastal tundra ecosystems located near Prudhoe Bay, Alaska indicate that CH4 flux to the atmosphere is strongly controlled by soil moisture content and the depth of the seasonally thawed soil active layer. Daily CH4 flux from a flooded and well drained site on the Prudhoe Bay oil fields was on average 0.7 and 0.1 gC m-2 day-1, respectively over both sampling seasons. Daily CH4 flux in an area located approximately 50 km south of Prudhoe Bay was considerably higher. This area (APL 133-3) contained a flooded, moist, and dry site which emitted on average 1. 5, 1. 1, and 0.2 gC m-2 day-1 to the atmosphere, respectively over both sampling seasons. These flux rates represent significant inputs of CH4 to the atmosphere. Evidence of the importance of soil moisture and thaw depth in controlling CH4 flux, coupled with the predominantly waterlogged, anaerobic conditions of wet tundra soils, suggest the potential for strong interactions of this soil-atmosphere system with global climate change.