CO2 exchange in a subarctic sedge fen in the Hudson Bay Lowland during two consecutive growing seasons

Abstract

Net ecosystem carbon dioxide exchange (NEE) was measured using the eddy covariance (EC) technique at a wetland tundra-sedge fen near Churchill, Manitoba, Canada during two consecutive growing seasons (2007 and 2008). Mean daily NEE at the fen (DOY 157-254) was -3.5 (± 0.26 S.E.) g CO2 m-2 d-1 in 2007 and -4.6 (± 0.36) g CO2 m-2 d-1 in 2008. The fen was a net carbon dioxide (CO2) sink during both the 2007 and 2008 growing seasons of -343 (± 79) and -450 (± 87) g CO2 m-2, respectively. Mean air temperature during the summer (June 1-August 31) was about 1°C greater than the historical average (1971-2000) in 2007 and about 2°C greater in 2008. Growing season precipitation was 107.5 mm below normal in 2007 and 359.5 mm above normal in 2008. These data suggest that if future climate change brings warmer temperatures and near-to-above average precipitation maintaining the water table near the surface, similar subarctic ecosystems will experience increased gross ecosystem productivity enhancing CO2 sequestration during the growing season.