A methane flux time series for tundra environments

Abstract

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 (± 1σ) 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 Carex‐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.

An ecosystem simulation model for methane production and emission from wetlands

“…In further contrast to field observations, our model is not designed to predict major differences among plant community types with respect to average soil T and thaw depth dynamics. For example, tussocks are generally taller than surrounding vegetation types, such that these areas might be expected to thaw at an earlier date by effectively absorbing lowangle solar radiation [Whalen and Reeburgh, 1988]. This extra heat transfer process is not included in our model design, and consequently, the tussock site is predicted to warm at about the same rate as the other two plant communities.…”

Nitrous oxide emission from an agricultural field fertilized with liquid lagoonal swine effluent

“…Nitrous oxide flux measurements were made using the static chamber technique [Whalen and Reeburgh, 1988]. Briefly, open-bottomed, cylindrical polyvinyl chloride covers (20 cm diameter x 9 cm height) fitted with a butyl O-ring were inserted onto the permanent soil collars to isolate 0.031 m 2 of soil surface and 5.3 L of overlying air.…”

A CH4emission estimate for the Kuparuk River basin, Alaska

“…Many of the available CH4 flux measurements, which are reviewed by Bartlett and Harriss [1993], have resulted from short-term campaigns that frequently span only a portion of the growing season. Winter flux measurements are rare [Whalen and Reeburgh, 1988;Dise, 1992]. There is a strong North American bias in CI-I4 flux data sets, and additional transect measurements and long-term observations similar to those by Chrtstensen et al [ 1995] and Panikov et al [ 1993] are needed.…”