西藏沙化动态及其原区

西藏自治区是我国沙化最严重的地区之一。2004年调查结果表明，西藏沙化面积为216842．7km^2其中重度以上的沙化面积占总沙化面积的91．53％；沙化类型以戈壁占绝对优势：草地、未利用地是主要的沙化土地利用类型。全区沙化总体上呈恶化趋势，沙化土地面积增加，沙化程度加剧，但拉萨、山南等地沙化土地有所减少。西藏土地沙化变化是受自然因素与人为因素共同作用的结果。

Analysis on Dynamic Changes and its Causes of Sandy Desertfication in Tibet

Tibet is one of the regions in which there is the most serious sandy desertification in China. The nearest researching result shows that there is 216842.7km^2 sandy desertified land in Tibet.The sandy desertification degree is very serious and severe sandy desertified land area occupies 91.53 % of the whole desertfied land area.Gobi is the main sandy desertification type.Unused land and grassland are the main landuse types which have been suffered sandy desertification.There is an aggravation trendency of sand desertification in Tibet, compared with the past.As a whole,desertifed land area expands and the desertified degree becomes more serious,while in Lasa and Shannan areas,there is a reduction trendency of sandy dertification land.The changes of sandy desertification in Tibet is resulted from the comprehensive effects of natural and human factors.