水热条件对不同坡位兴安落叶松林土壤CH4通量的影响

兴安落叶松林是我国北方最大的针叶林，在我国具有重要的碳汇地位，对我国以及全球的气候变化具有重要影响。由于独特的高寒高湿和多年冻土的特殊生态环境，兴安落叶松林土壤中 CH4的吸收与释放的规律与众不同。因此，开展对土壤 CH4动态及其与环境关系的研究，对揭示兴安落叶松林碳汇能力的形成、碳释放动态以及兴安落叶松林对气候变化的作用具有重要的理论和实践意义。作者于2011年5月到9月间在内蒙古根河国家生态站，在不同坡位的4种典型兴安落叶松林群落中布设样地，采用静态箱-红外气体分析仪收集气体并分析CH4通量的变化，同时测定不同深度的土壤温度，测定土壤含水率。借助SAS方差分析、相关性分析等统计方法，对兴安落叶松林土壤CH4通量的季节变化进行研究，同时分析土壤温度及含水率对 CH4通量的影响。结果表明，CH4的季节动态变化规律：坡顶 CH4通量为春季释放，夏季吸收，秋季释放，吸收大于释放，通量的平均值为-68.12μg·m^-2·h^-1；坡上部CH4通量为春夏秋3季均吸收，通量的平均值为-342.49μg·m^-2·h^-1；坡下部CH4通量为春季释放，夏季吸收，秋季释放，释放大于吸收，通量的平均值为67.8μg·m^-2·h^-1；坡脚CH4通量为春夏秋3季均释放，通量的平均值为263μg·m^-2·h^-1。总的来说，在生长季兴安落叶松林土壤甲烷通量吸收大于释放，说明地处寒温带的大兴安岭是CH4的汇。观测期间CH4通量与温度及土壤含水率均有一定的相关性，二者从不同角度影响CH4通量的变化，而随着坡位的变化土壤水热条件也随之改变，这同样是影响CH4通量的一个重要因素。

Impact of water and temperature on soil CH4 fluxes of Larix gmelinii of different slope positions

Larix gmelinii forest area is the largest of coniferous forests in north China, is an important carbon sink of China, and has important influence on Chinese sequstration and the global climate change. Because of its highly humid, cold and frozen environment, the dynamics of absorption and release of soil CH4 in Larix gmelinii forest is different from others. Therefore, the research on soil CH4 dynamics and its relationship with environment has an important theoretical and practical significance to reveal the local forest carbon dynamics and its effect on climate change. Study sites were selected in different slope positions of four kinds of typical Larix gmelinii forest communities in Inner Mongolia Genhe national ecological research station and done in May to September of 2011. The CH4 were collected by static box and analyzed by an automatic cavity ring-down spectrophotometer, and measured the soil temperature of different depth and soil moisture content as well, Using variance, correlation analysis and other statistical methods, we studied the monthly changes of soil CH4 fluxes, and analyzed the effect of soil temperature and moisture content on CH4 fluxes. Results showed as follow：（1） Soil CH4 in hilltop emitted in spring, uptook in summer, and released again in autumn in hilltop. Uptaking was greater than emission, the average flux of top slope is-68.12μg·m^-2·h^-1. （2） Soil CH4 in upper part of slope uptook in spring, summer and autumn, the average flux of upper part of slope is-342.49μg·m^-2·h^-1 （3） Soil CH4 in lower part of slope emitted in spring, uptook in summer, emitted again in autumn, emission is greater than absorption, the average flux of lower part of slope is 67.8μg·m^-2·h^-1. （4） Soil CH4 in bottom of hill emitted in spring, summer and autumn, the average flux of the bottom of slope is 263 μg·m-2·h-1. On the whole, the result of soil CH4 fluxes of Larix gmelinii was absorption is greater than emission, this shows that Greater Higgnan Mountains which located in cold temperate zone is the sink of CH4. CH4 fluxes has certain correlation with temperature and soil moisture content at all times during the observation, these two factors affect the change of CH4 fluxes from different aspects, and with the change of slope positions, soil environmental conditions changed as well, this is also an important factor affecting CH4 fluxes.