METHANE AND CARBON-DIOXIDE EXCHANGE POTENTIALS OF PEAT SOILS IN AEROBIC AND ANAEROBIC LABORATORY INCUBATIONS

Samples (140) of peat collected from bogs, fens and swamps in boreal, subarctic and temperate regions of Canada were incubated at 15 or 20 d egrees C for 5 d in the laboratory to determine potential rates of CO2 and CH4 exchange under aerobic and anaerobic conditions. Rates of CO2 production ranged between 0.07 and 5.0 mg g(-1) d(-1), with means of 1.0 and 0.5 mg CO2 g(-1) d(-1) for aerobic and anaerobic production ra tes, respectively. Aerobic and anaerobic CO2 production rates were str ongly correlated (r = 0.581, P < 0.001, log(10) transformation) with t he former an average of 2.5 times larger than the latter. CO2 producti on rates were greatest in the upper part of peat profile and appeared to be re lated to the botanical origin of the peat. Aerobic CH4 consum ption and anaerobic CH4 production rates ranged from 0.01 to 100 mu g CH4 g(-1) d(-1), with means of 13.1 and 3.1 mu g CH4 g(-1) d(-1), resp ectively. Rates of CH4 exchange were positively correlated (r = 0.368, P < 0.001, log(10) transformation). Within profiles, maximum CH4 cons umption occurred in samples collected from beneath or at the water tab le, whereas CH4 production occurred mainly in samples collected from b eneath the water table. There was no significant correlation between a erobic CH4 consumption and CO2 production, but anaerobic CH4 productio n was positively correlated with CO2 production (r = 0.36, P < 0.001). (C) 1997 Elsevier Science Ltd.