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

Abstract

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.