PLANT -DEPENDENT CH4 EMISSION IN A SUBARCTIC CANADIAN FEN

The importance of vegetation in affecting CH4 emissions was investigated in a Carex-dominated fen located near Schefferville, Quebec, and in the Experimental Lakes Area, Ontario. Comparison of emission rates with and without the presence of aboveground vegetation indicated that over 90% of the emission was plant-associated transport. Further evidence of this association was found in a linear correlation of CH4 emission with aboveground plant biomass (R=0.93). To test the importance of aboveground plant photosynthetic production on methane production, aboveground vegetation was clipped from sites continually over the growing season. Both emissions and dissolved pore water CH4 were reduced relative to adjacent vegetated areas. A significant correlation (R=0.93) of CH4 emissions with net CO2 exchange in this fen gives evidence of the close association between new plant production and methanogenesis.