柴达木河都兰区植被覆盖率变化特征

柴达木河都兰区位于青海柴达木盆地东南部，干旱少雨，生态环境脆弱。基于MODIS NDVI数据，应用遥感方法，对都兰区2000—2011年的植被覆盖率进行了计算，并分析了其影响因素。结果表明：研究区内裸土和低覆盖率植被的面积逐年减小，而较低覆盖率、中等覆盖率、较高覆盖率及高覆盖率植被的面积均逐年增加；研究区植被覆盖率与降水及相对湿度呈正相关关系，区域植被生长与地下水埋深的关系较为密切；宗加-诺木洪植被区的地下水埋深范围为0.7～3.5 m，在水埋深为1.7 m的地方，植被长势最好；当研究区的地下水水质矿化度小于3 g·L^-1时，植被发育较好。

Variation of Vegetation Coverage in the Dulan Area of Qaidam River Basin

The climate of Dulan area, located in southeast part of Qaidam basin in Qinghai province, is arid and the eco-environment is very fragile. Based on MODIS NDVI, the vegetation coverage of Dulan area during the period of 2000-2011 was estimated and the impact factors were also discussed using remote sensing method. The result indicated that areas of bare soil and low vegetation coverage were decreased with time. On the contrary, the areas of low-moderate, moderate, moderate-high and high vegetation coverage were increased with time. The correlation between vegetation coverage and precipitation, relative humidity is positive. The groundwater depth has important impact on vegetation. The corresponding interval of groundwater depth to vegetation in Zongjia-Nuo Muhong area is 0.7 m to 3.5 m. The vegetation growth is better when the groundwater depth is 1.7 m. The vegetation growth is also well when total dissolved solids (TDS) is smaller than 3 g·L^-1 in the studied area.