Methane emissions from wetlands in the Midboreal region of northern Ontario, Canada
- McGill Univ., Quebec (Canada)
- York Univ., Ontario (Canada)
Methane (CH[sub 4]) fluxes were measured by a static chamber technique from May to October 1991 at 19 wetland sites near Cochrane, northern Ontario, representative of the Clay Belt Midboreal region of central Canada. Seasonal average fluxes of CH[sub 4] from the peatlands ranged from 0.4 to 67.5 mg[center dot]m[sup [minus]2][center dot]d[sup [minus]1] (0.06-10.1 g[center dot]m[sup [minus]2][center dot]yr[sup [minus]1]). Beaver ponds showed the highest fluxes of CH[sub 4], from both the open water section (seasonal average 290 mg[center dot]m[sup [minus]2][center dot]d[sup [minus]1], 44 g[center dot]m[sup [minus]2][center dot]yr[sup [minus]1]) and the adjacent marsh areas where the water table rose close to or above the soil surface (91-350 mg[center dot]m[sup [minus]2][center dot]d[sup [minus]1], 13-53 g[center dot]m[sup [minus]2][center dot]yr[sup [minus]1]). Seasonal mean water table position, particularly at the microtopographic scale of hummock and hollow, explained most of the variability in CH[sub 4] emission among wetlands (r[sup 2] = 0.74). Trophic status, such as pore-water Ca, Mg, and pH had little correlation with CH[sub 4] emissions. Broad-scale peatland classifications that do not account for hydrological differences at the microtopographic level are inadequate for predicting CH[sub 4] flux in boreal wetlands, particularly in forested ecosystems where conifer swamps are diverse and comprise the major peatland class. Based on areal estimates of the different wetland types in the Clay Belt, the authors estimate an annual CH[sub 4] flux of 3.4 g[center dot]m[sup [minus]2][center dot]yr[sup [minus]1], generally lower than that used in extrapolations to continental- or global-scale methane budgets. 68 refs., 5 figs., 6 tabs.
- OSTI ID:
- 5298697
- Journal Information:
- Ecology; (United States), Vol. 74:8; ISSN 0012-9658
- Country of Publication:
- United States
- Language:
- English
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