典型退耕还林区景观格局变化特征

以1990、2001、2006年3个时期的Landsat TM遥感影像和1999年的森林资源分布图为数据源,运用景观格局分析方法,结合遥感与地理信息系统技术,对典型退耕区沐川县土地利用与覆盖变化进行分析,结果表明:退耕区耕地面积随时间的变化成逐年下降趋势,林地面积中变化最大的是竹林,且变化时期主要在1999—2001年。1999—2001年间,在西南部高丘河谷平坝区,斑块的多样性增大,破碎度增加;在海拔较高的区域,破碎度变小。人为干扰是土地利用变化驱动力的重要因素,由于退耕还林工程实施及地方政策的引导,低海拔地区土地利用变化明显。

Characteristics of Landscape Pattern Changes in Typical Region of Cropland Conversion to Forest Land

Landsat-5 TM images of 1990,2001,2006 and the forest resource distribution map of 1999 for Muchuan County were used as information sources.The supervised classification techique combined with the expert knowledge was used for classification with the accuracy reaching 81.42%,86.52% and 86.10% respectively.Besides,landscape analysis methods together with RS and GIS techniques were introduced for analysis of the LUCC(Land Use and Cover Change) of Muchuan County.The results demonstrated that farmland areas decreased gradually with the change of time.By 2006,farmland areas reached only 42.15% of the total study region.Bamboo forest had great change in forestry land from1999 to 2001.Newly planted bamboo forest from 1999 to 2001 had negative effect on landscape connectivity,and the fragmentized rate of landscape reached its maximum which strengthened the infiltration correlated with biological behavior or biological course.In those areas with high altitude,the project of farmland conversion to forestry land had less influence on farmland and the fragmentation of landscape got small.At the same time,human activities are main impacts on fragmentation of landscape in those areas at low altitude.