气候和放牧对锡林郭勒地区植被覆盖变化的影响

基于锡林郭勒盟15个气象站点1981-2007年的逐月气温、降水量数据及各旗县的牲畜头数，在ArcGIS软件的支持下，分析气候干燥度和牲畜密度的空间分布，结合1981-2007年的逐旬归一化植被指数（NDVI）数据，对研究区植被覆盖变化的驱动因素进行分析.结果表明： 研究期间，锡林郭勒盟气候干燥度与植被覆盖状况之间存在良好的线性回归关系；NDVI与牲畜密度之间存在良好的二项式回归关系，随着NDVI值的升高，牲畜密度先增加后降低；植被覆盖状况与干燥度和牲畜密度呈复线性相关关系，其中，NDVI与干燥度呈正相关，与牲畜密度呈负相关，且干燥度对NDVI的影响远大于牲畜密度对NDVI的影响.

An assessment of agricultural non-point source pollution in Ningxia irrigation region,Northwest China

Based on the monthly temperature and precipitation data of 15 meteorological stations and the statistical data of livestock density in Xilinguole League in 1981-2007, and by using ArcGIS, this paper analyzed the spatial distribution of the climate aridity and livestock density in the League, and in combining with the ten day data of the normalized difference vegetation index (NDVI) in 1981-2007, the driving factors of the vegetation cover change in the League were discussed. In the study period, there was a satisfactory linear regression relationship between the climate aridity and the vegetation coverage. The NDVI and the livestock density had a favorable binomial regression relationship. With the increase of NDVI, the livestock density increased first and decreased then. The vegetation coverage had a complex linear relationship with livestock density and climate aridity. The NDVI had a positive correlation with climate aridity, but a negative correlation with livestock density. Compared with livestock density, climate aridity had far greater effects on the NDVI.