关键词: 大兴安岭, 多年冻土变化, 气候变暖, 人为扰动

Abstract: The Mt. Dahinggan Ling is the high-latitude large permafrost distribution area in China. The permafrost in the region shows an apparent tendency of degeneration. In Amur area, the permafrost also presents an obvious degeneration trend during 1978-1991. (1)The seasonally thawing depth has deepened more than 30cm. The ground temperature at the depth of 20cm has gone up 0. 8℃. (2)The mean annual ground temperature has increased 2. 1-0. 7℃. The thickness of permafrost has reduced 17-52m.(3)The area of talik is expanding. In the I and Ⅱ level terraces and the sunny slope terrains, the high temperature makes the thin permafrost get into ablation gradually and finally leads to talik. The permafrost boundary in Amur North Gully declined about 80m towards the bottom of Gully.The reasons for the change of permafrost are summed up as follows:(l)Climate warming.The mean annual air temperature of the last 30 years has increased about l.6℃. It is a major contributor to regional degeneration of permafrost in the Mt. Dahinggan Ling region. Climate warming can also lead to a rise in the amount of snowfall in winter and a ground surface temperature increase. The increase of the thickness of snowcover would also contribute to the degeneration of permafrost. (2)Influence of the increasingly intense human activity. The increasingly intense human activity has led to severe damages to the vegetation and increase of permafrost ground temperature. It is a major contributor to the local dengeneration of permafrost. 

Key words: Da hinggan Ling, change of permafrost, climate warming, human turbulence