[Effects of forest cutting on greenhouse gas emissions from Larix gmelini-Sphagnum swamps in Lesser Xing' an Mountains of Heilongjiang, China].

By using static chamber and gas chromatography methods,this paper studied the effects of clear cutting and selective cutting on the CO_2,CH_4,and N_2O emissions from Larix gmelini-Sphagnum swamp in Lesser Xing'an Mountains.Dramatic changes in the seasonal dynamics of CH_4 and N_2O emissions were detected in different treatment sites.Control site absorbed CH_4 in summer and emitted CH_4 in autumn,and absorbed N_2O in both summer and autumn;selective cutting site emitted CH_4 and N_2O mainly in summer;and clear cutting site emitted CH_4 in summer and autumn,and absorbed N_2O in summer but emitted it in autumn.Cutting pattern had less effects on the seasonal dynamics of CO_2 emission.Both on the clear cutting site and on the selective cutting site,the CO_2 emission was in order of summerspringautumn.Forest cutting altered the source and sink functions of the sites.Control site functioned as a source of CO_2 and a weak sink of CH_4 or N_2O,while forest cutting sites had a decrease of CO_2 emission by 25%,and became a weak source of N_2O and a weak or strong source of CH_4.Compared with that of control site,the Global Warming Potential(GWP)of selective cutting site and clear cutting site was reduced by 24.5% and increased by 3.2%,respectively.