Factors influencing methane flux from a boreal forest wetland in Saskatchewan, Canada

Methane flux in a boreal wetland in central Saskatchewan, Canada was measured by a static chamber technique. The northern ribbed fen site was part of the Boreal Ecosystem and Atmospheric Study. The results indicated temperature, water level relative to the peat surface, vegetative type and P concentrations in interstitial water all had an influence on CH4 emission rates. Methane fluxes from peat at the site ranged from 176 to 2250 mmol CH4 m−2 yr−1, exceeding those commonly reported for other freshwater wetlands around the world. The CH4 flux rates increased from 1.08 at the edge of the fen to 13.80 mmol CH4 m−2 d−1 near the center. Methane flux was directly correlated with water levels and temperature at all measurement locations except two in the central part of the fen where fluxes became lower. The lower correlation of water levels and temperature with CH4 flux in sites located at the fen center may be attributed to other more restricting variables created by the water flow through the center of the fen. Methane flux rates in sites with limited water flow were also positively correlated with P concentrations in interstitial water at 50 cm, the depth where CH4 is likely to be produced.