19752009年锡林郭勒盟东部地区草地退化态势及其空间格局分析

The Tendency and its Spatial Pattern of Grassland Changes in the East Xilin Gol from 1975 to 2009

研究采用锡林郭勒盟东部3旗、市(东乌珠穆沁旗、西乌珠穆沁旗以及锡林浩特市)1975年MSS数据、1990、2000、2005年的Landsat TM数据,以及2009年的HJ-1等遥感影像,在分析研究区陆地植被覆盖与变化特点的基础上,建立了研究区草地变化遥感解译的分类系统,构建了锡林郭勒盟东部地区5期草地现状、4期草地退化数据库;基于该数据,进一步分析了锡林郭勒盟东部草地变化态势的时空分布格局。研究表明:1975年以来锡林郭勒盟东部区草原一直处于退化状态,但2000年之前为持续、加速的退化过程,2000年之后草地退化态势得到遏制和缓解;草地破碎化与盖度降低是本区的主要退化类型,2000年之前上述退化过程是由西向东,即由锡林浩特向东乌珠穆沁、西乌珠穆沁两旗扩展,2000年之后上述退化过程则是由东向西收缩。

Using remote sensing images including MSS images in the middle and late 1970s,TM images in 1990,2000,2005 and HJ-1 images in 2009,the grassland changes database in eastern Xilin Gol League（East Ujimqin Banner,West Ujimqin Banner and Xilinhot City） including grassland current situation data for five periods was firstly developed,and then a grassland change classification system was established based on these images and regional geographic principle.Then,supported by GIS,the temporal and spatial distribution pattern of grassland changes in eastern Xilin Gol was analyzed deeply.The main results include： the grassland in eastern Xilin Gol existed a long-term degradation process during the period from 1975 to 2009.The year of 2000 is a breaking point： before the year of 2000,grassland change in eastern Xilin Gol was in an accelerated degradation process,and the percentage of degradation area climbed.During 1975-2000,the strength and range of the grassland degradation reached the most serious and intensive peak;after the year of 2000,although the degraded ared was larger than those improved,the deference between them was narrowed and the whole changed area was reduced;the speed and space range was reduced obviously,and the previous accelerated degradation process was contained.Judging from the spatial distribution,as the main degradation type,grassland fragmentation and coverage reduction expanded from Xilinhot to East Ujimqin and West Ujimqin before 2000,and then shrinked to Xilinhot from East Ujimqin and West Ujimqin after 2000.The other type of grassland change,i.e.improved grasses,showed a similar spatial distribution pattern with those of grassland fragmentation and coverage reduction.