西藏荒漠化动态变化研究

西藏是青藏高原主体,也是环境敏感和荒漠化比较严重的区域之一。掌握西藏荒漠化的动态变化对于该区荒漠化治理规划的制定和实现国土资源的可持续利用具有重要意义。利用西藏的两期荒漠化监测数据进行了对比分析研究。结果表明,与1999年相比,目前西藏荒漠化总体上呈恶化趋势,但局部得到逆转。1999年～2004年的5年间,西藏荒漠化面积增加6.47万hm^2;荒漠化程度有加重趋势,表现为轻度荒漠化、重度荒漠化和极重度荒漠化面积分别减少8.26%、1.78%和0.41%,中度荒漠化面积增加10.45%;荒漠化空间分布发生了一定的变化,干旱区荒漠化面积减少11.17万hm^2,而半干旱区和亚湿润干旱区的荒漠化呈一定的扩展趋势（未统计冻融荒漠化土地）,其中阿里、日喀则地区荒漠化面积扩大,其他区的荒漠化面积则有不同程度的减少。气候暖化和降水变化是西藏荒漠化变化的主要原因,但人为因素对西藏荒漠化的发展起了一定的促进和缓解的作用。

Study on the Dynamic Changes of Desertification in Tibet

Tibet is the main body of Qingzang Plateau. It is also an environmentally sensitive area and one of the regions in which there is serious desertifieation in China. To grasp the dynamic change of desertifieation in Tibet is very important to make controlling plan and achieve sustainable use of land resource. Using the monitoring data of different times, the dynamic changes of desertifieation in Tiabet was analyzed and studied. The result showed that compared with the data in 1999, there is a general tendency of aggravation of desertifieation in 2004, but the desertifieation condition takes a favorable turn in local area. During five years from 1999 to 2004, the desertified area is expanded for 64 725.1 hm^2. The desertifieation degree becomes more serious which shows that slight degree and severe degree and very severe degree desertified land area reduce 8.26%, 1.78% and 0.41% respectively, but moderate degree desertifieation land area adds 10.45 %. The spatial distribution of desertified land takes certain change. The desertified land area diminishes for 111 677.7 hm^2 in dry area while it is enlarged in semi-dry area and sinai-humid area. The desertified land is expanded in Ali district and Rikaze district, while there exits different degree of diminution in the other area in Tibet. The main reason of the dynamic changes of desertifieation in Tibet is the climate changing, and faetitious factors make contribution to it together.