以云南省为例,探讨利用地理信息系统技术来确定需要退耕还林还草的耕地数量及其空间分布。其中包括 4个步骤。首先,建立土地利用、土壤侵蚀、坡度、植被指数、水体、降雨和温度等数据库。其次,从土地利用数据库中提取旱地的数据,并与坡度数据、土壤侵蚀数据、植被指数数据进行叠加分析。对水体建立缓冲区,并与耕地数据进行叠加分析。再次,确定退耕还林还草的原则,并在 GIS的支持下,确定需要退耕还林还草的空间分布及其面积。最后,利用降雨和温度数据进一步确定分别退耕还林和还草的空间分布及其面积。研究结果可以为云南省的生态环境建设提供科学的依据。

The strategy to develop China’s western region has been proposed by the central Governmant and ecological environmental construction constitute a very important part of the strategy. In order to improve the ecological environment of China’s western region, a great deal of the dry upland must be reforested and regrassed. Where the dry upland must be changed into the forestland or grassland is quite essential GIS is identified as a useful tool to find the place where the dry upland must be changed into forestland or grassland in Yunnan province, Southwest China. Four steps are included. Firstly, relevant databases are established including land use database, elevation database, slope database, soil erosion database, water body database, precipitation database and temperature database. Secondly, the dry land from landuse database was overlain with slope database, soil erosion database, normalization vegetation index(NDVI) database. The distribution of the dry land of different slopes was analyzed. The distribution of the dry land of different slopes under different soil erosion conditions with different NDVIs is also analyzed. Thirdly, the expert knowledge about the upland cultivated was collected, and the model for finding the suitable place for being returned back to forestland or grassland is formulated on the basis of the knowledge. Finally, the suitable place is overlain with the precipitation layer and temperature layer to decide where trees need be planted and where grass need be planted. It shows that the results are very useful for the ecological environment construction in Yunnan Province.