A METHANE FLUX TIME SERIES FOR TUNDRA ENVIRONMENTS

Seasonal measurements of net methane flux were made at permanent sites representing important components of arctic tundra. The sites include Eriophorum tussocks, intertussock depressions, moss-covered areas, and Carex stands. Methane fluxes showed high diel, seasonal, intra site, and between site variability. Eriophorum tussocks and Carex dominated methane release to the atmosphere, with mean annual (+/- l sigma) net methane fluxes of 8.05 +/- 2.50 g CH4 m(-2) and 4.88 +/- 0.73 g CH4 m(-2), respectively. Methane fluxes from the moss sites and intertussock depressions were much lower (0.47 +/- 0.16 and 0.62 +/- 0.28 g CH4 m(-2) yr(-1). Over 90% of the mean annual methane flux from the Eriophorum, intertussock depressions, and Carex sites occurred between thaw and freeze-up. Some 40% of the mean annual methane flux from the moss sites occurred during winter. Composite methane fluxes for tussock tundra and Cares-dominated wet meadow tundra environments were produced by weighting measured component fluxes according to areal coverage. Tussock and wet meadow tundra account for an estimated global methane emission of 19-33 Tg yr(-1).