青藏公路南段岛状冻土区内冻土环境变化

Environmental Change in Patchy Permafrost Zone in the South Section of the Qinghai-Tibet Highway

将９０年代的勘探、钻孔测温和地面综合调查等实测资料与７０年代对比，发现青藏公路南段岛状多年冻土区内的冻土退化和生态环境变化相当明显。表现为岛状多年冻土南界北移１２ｋｍ，多年冻土岛总面积减少７％。沼泽化湿地面积缩小约三分之一，沼泽化草甸向草原化草甸逐步转化，湖塘和洼地中的水生植物群落向湿、中生植物群落演替。草场退化严重，少数地段土地沙化，形成活动性砂丘，目前区内的生态环境正向劣势方面发展。

Comparing the ground temperature and other investigation data in the 1990's with those in the 1970's, it is found that the permafrost degradation and the eco-environmental change is significant in the patchy permafrost zone in the south section of the Qinghai-Tibet Highway The southern limit of permafrost moved northwards about 12 km The area of patchy permafrost decreased 7% The area of swamp land decreased about one third The swamp meadow gradually changes into grassy meadow, and the aquatic plants in lakes and low wet lands were replaced by moderate hygrophilous plants Along with serious degradation of grassland, some lands were desertificated and movable sand dune formed The eco-environment becomes worse gradually