Vegetation coverage and its relationships with temperature and precipitation in Ningxia in 1981-2004
宁夏近20年来植被覆盖度及其与气温降水的关系

Based on the 1981-2004 NDVI(Normalized Difference Vegetation Index)data and the survey of ground vegetation,the vegetation types in Ningxia were divided into four regions,and the relationships between vegetation index and vegetation coverage were identified.The inter-annual,seasonal,and area changes of the vegetation coverage in the four regions,as well as the relationships of these changes with temperature and precipitation were analyzed.The results showed that since 1981,the vegetation coverage in Helan Mountain and its eastern foot had a decreasing trend,while that in central arid region was in adverse.Overall,the vegetation coverage in the recent 4 years turned better in Helan Mountain but worse at its eastern foot,better in autumn and worse in summer in central arid region,and better in southern mountain region.The precipitation in spring and summer was the key factor affecting the vegetation coverage in Ningxia,while temperature had less effect.