NITROUS-OXIDE AND METHANE FLUXES FROM PERTURBED AND UNPERTURBED BOREAL FOREST SITES IN NORTHERN ONTARIO

Boreal forests cover approximately 11% of the terrestrial surface of t he world or 14.7 million km(2) in the circumpolar region of the northe rn hemisphere. Of this total, approximately one third of these forests are found in Canada. This accounts for on the order of 50% of the tot al land area in Canada. A static chamber technique was used to determi ne the fluxes of nitrous oxide and methane from four Boreal forest sit es near Cochrane, Ontario (49 degrees 03'N,80 degrees 40'W), during th e summer of 1992. The four sites included a lowland forest, a drained lowland forest, a clear-cut and drained lowland forest, as well as an upland forest. The N2O fluxes ranged from an uptake of 7.7 mu g(N2O)/m (2)/hr from a drainage ditch to an emission of 3.1 mu g(N2O)/m(2)/hr f rom an unvegetated clear-cut region. The CH4 fluxes ranged from an upt ake of 23 mu g(CH4)/m(2)/hr from an upland forest site, to an emission of 2900 mu g(CH4)/m(2)/hr from a drainage ditch. Drainage ditches whi ch contained a large amount of algae exhibited large CH4 production an d large N2O uptake.