中文摘要：

利用黄河源地区1985年和2000年1：100000土地利用／覆被数据，结合1：250000DEM、道路和居民点数据与野外调查资料，分析草地退化与坡向、海拔及距道路和居民点距离之间的关系．探讨黄河源区15年间土地覆被变化特征与规律。结果表明，退化草地占源区总面积的8．24％，冬春季牧场退化率显著高于夏季牧场：草地退化是黄河源区研究时段内土地利用／覆被变化最主要的特征。草地退化表现为：①阳坡退化率高于阴坡；②受人口密度影响，草地退化率与海拔高度成反比，相关系数为．0．925；③距离居民点越近。退化率越高。尤其当与居民点距离≤12km时，草地退化率与其相关系数高达-0．996；④在距道路4km以内．草地退化率与道路距离成反比．相关系数高达-0．978。1985年以来，源区的草地退化有自然因素的影响．但人类活动的影响仍起主导作用。科学地减少当地居民对草地的过分依赖是解决脆弱的江河源区环境退化的根本。

英文摘要：

The source region of the Yellow River located in the middle east of Tibetan Plateau. The total area is about 52 000 km^2, mainly covered by grassland （79%）, unused land （16%） and water （4%）. The increasing utilization of the land in this area have been keeping increasing the risk of environmental degradation. The land use/cover data （1985 and 2000） provided by the Data Center for Resources and Environmental Sciences of Chinese Academy of Sciences, have been used to analyze the land cover change of the Yellow River. DEM （1： 250 000） data, roads, residents data （1：100 000） and the collecting field data were used to analyze grassland degradation distribution character. The Arcgis 9 software was use to convert data types and do the overlay, reclass, zonal statistic analysis. Results show that grassland degradation is the most important land cover change in the research region, which occupied 8.24% of the whole region. And human activities are the main reasons of the grassland degradation in the source region of Yellow River： a） the degradation rate is higher in the sunny slope and lower in the northern slope; b） The grassland degradation rate goes down while the elevation rise up with the correlation coefficient of-0.93; c） The nearer to the residents the higher degradation rate, especially in the range of 11km, of which the correlation coefficient of the distance and degradation rate is -0.99; d） In the range of 4km, the degradation rate goes down with the distance to the roads with the correlation coefficient of -0.98. Though there are some physical reasons, human activities are the most important driven forces of the grassland degradation in the source region of the Yellow River since 1985. The ultimate way to resolve the degradation problems is to decrease the population who depends on the livestock production and to lessen the society demand of the GDP incoming from the grassland. To keep the sustainable development, the management and dynamic process of the grassland ecosys