陕北黄土丘陵区近30年来土地利用动态变化分析

Analysis of Dynamic Landuse Changes of Past 30 Years in the Hilly Area of Loess Plateau

为了对延安中尺度生态建设试验示范区(简称延安试区)近30a的土地利用类型动态变化做出初步的分析,利用1975,1986,1997和2003年延安试区的遥感影像进行计算机自动分类得到延安试区的土地利用图。然后利用GIS空间分析方法和数理统计方法对得到的土地利用图进行分析,得出近30a延安试区各土地利用类型的变化幅度、变化速度、变化方向、空间格局变化特征。结果显示,在近30a间,耕地面积的总趋势是减少,草地面积不断减少,而林地和居民地面积都有很大幅度的增加;居民地和林地的年变化速率一直高于其它土地利用类型;各土地利用类型主要向林地变化;林地的变化区域主要在南部林区,耕地和草地的变化在整个研究区域均有发生,居民地和水体的变化主要分布在沟道和河道两岸。

The purpose of the article was to make a preliminary analysis of dynamic landuse change in Yan＇an experimental area in the past 30 years. The landuse information was extracted from the remotely sensed imagery in the years of 1975, 1986, 1997, and 2003. Based on these thematic maps, the range, speed, direction, and spatial features of landuse change were analyzed by the combined means of GIS spatial analysis and statistics analysis. Results showed that in the past 30 years, the area of cropland was lowered sharply and the area of grassland was reduced. However, the area of forest land and the residential area were increased greatly. The annual speed of increased forest land and residential areas were higher than that of others. The direction of landuse type change was mainly toward forest land. The change of forest land mainly occurred in the south forest area; the cropland and grassland, in the whole study region; the residential area and water area, mainly in the valley and river bank.