火干扰下的大兴安岭冻土活动层变化研究

Changes of Permafrost Active Layer in Greater Khingan Mountains Under Fire Disturbance

利用相似流域比较法,选取1987年特大森林火灾严重过火区与未火烧区的两个小流域作为研究区,通过野外实验获取两个流域的冻土活动层厚度以及相关的环境因子数据,利用多因子方差分析对火干扰下的冻土活动层及其环境因子进行研究。结果显示:有无乔木以及乔木的生长状况,苔藓层、泥炭层厚度以及土壤的机械组成等均与冻土活动层厚度呈显著相关。火烧区的乔木已完全消失,苔藓层分布不均匀而泥炭层的厚度则显著小于未火烧区,从而导致火烧区的冻土活动层厚度显著大于未火烧区。冻土层的变化将进一步引起冻土区湿地格局变化、林缘后退等生态环境问题。

In order to discuss the changes of permafrost active layer and environment factors under forest fire, two small basins which locate in burned area and unburned area respectively during the catastrophic forest fire in 1987 were selected as the study areas. The data of permafrost active layer and corresponding environmental variables, such as tree distribution, moss and peat thickness, were obtained by field survey. The results reveal that forest in burned basin has already disappeared and the peat soil in burned basin is sig- nificantly thinner than that in or unburned basin, which leads to thicker permafrost active layers in burned basin than in unburned basin using univariate analysis of variance. And then, a series of environmental problems may appear, such as wetland expanding and forest shrinking.