采伐对小兴安岭落叶松-泥炭藓沼泽温室气体排放的影响

利用静态箱-气相色谱法,研究了择伐和皆伐对小兴安岭落叶松-泥炭藓沼泽CH4、CO2、N2O排放的影响.结果表明:采伐改变了落叶松-泥炭藓沼泽CH4和N2O的季节排放规律,其中对照样地的CH4为夏季吸收、秋季排放,N2O夏秋季吸收;择伐样地的CH4和N2O在夏季集中排放;皆伐样地的CH4在夏秋季排放,N2O则在夏季吸收、秋季排放.但采伐对CO2季节排放规律的影响,均为夏季春季秋季.采伐改变了CH4、CO2和N2O的源汇功能,对照样地为CO2的排放源、CH4和N2O的弱吸收汇;采伐地的CO2排放量下降了1/4,并转化为N2O弱排放源,为CH4的弱排放源或强排放源.择伐样地温室效应贡献潜力较对照样地下降了24.5%,皆伐地则提高了3.2%.

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 CO₂, CH₄, and N₂O emissions from Larix gmelini-Sphagnum swamp in Lesser Xing’an Mountains. Dramatic changes in the seasonal dynamics of CH₄ and N₂O emissions were detected in different treatment sites. Control site absorbed CH₄ in summer and emitted CH₄ in autumn, and absorbed N₂O in both summer and autumn; selective cutting site emitted CH₄ and N₂O mainly in summer; and clear cutting site emitted CH₄ in summer and autumn, and absorbed N₂O in summer but emitted it in autumn. Cutting pattern had less effects on the seasonal dynamics of CO₂ emission. Both on the clear cutting site and on the selective cutting site, the CO₂ emission was in order of summer>spring>autumn. Forest cutting altered the source and sink functions of the sites. Control site functioned as a source of CO₂ and a weak sink of CH₄ or N₂O, while forest cutting sites had a decrease of CO₂ emission by 25%, and became a weak source of N₂O and a weak or strong source of CH₄. 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.