吴起县退耕还林工程实施前后土地利用/覆盖变化

以陕西省吴起县1998、2007年2景遥感影像为基础,以NDVI值、土地利用图和地面调查数据为依据,在GIS空间数据平台的支持下,采用空间分析和统计方法,对其近10年来的土地利用/覆盖变化情况进行了分析:1998—2007年,耕地面积占土地总面积的比例从19.68%减少到6.79%,林地面积从12.50%增加到38.43%,高覆盖度草地从14.44%增加到20.62%,中覆盖度草地从30.03%减少到20.07%,居民及建设用地比例呈稳定增加趋势。研究结果表明,吴起县退耕还林(草)等生态环境工程的实施,使当地的土地利用结构逐渐趋向合理,有效地提高了植被覆盖率,生态环境得到明显改善。

Variations of Land Use and Land Cover Before and After Project of Conversion of Cropland to Forest in Wuqi County

The paper analyzes the variations of land use and land cover in the last ten years by taking two remote sensing images of 1998 and 2007 of Wuqi County in Shaanxi Province,NDVI values,land-use maps and ground survey data as the basis,with the support of GIS spatial data and using the methods of spatial analysis and statistics.The results are as follows: during the period of 1998—2007,the proportion of cultivated land to the total land area is reduced from 19.68% to 6.79%,the proportion of forest area increased from 12.50% to 38.43%,the proportion of highly covered grass land increased from 14.44% to 20.62%,the proportion of medium-level covered grass land redused from 30.03% to 20.07% and the proportion of housing and construction land is in the trend of steady increases.The outcomes show that the implementation of eco-engineering including the project of conversion of cropland to forest(grassland) has gradually made the land use structure in the trend of reasonable and increased the coverage of vegetation effectively and improved the entironment remarkably.