Dynamics of land-use for natural grassland based on 3S——A case of the national natural reserve in Xilinguole grassland

Land-use and land vegetation coverage changes are the most obvious aspects of global change and the important factors that influence the quality of grassland ecosystem.We used land-use dynamic degree model and land-use transition matrix to study the changing rate and changing direction of land type based on the TM RS image data of 1987,2000 and 2005 in study area.The results were as follows,(1) the natural reserve displayed land degradation significantly,the general trend of land-use changes were reducing of the grassland and waters,and increasing of the area of cultivated land,sandy land,marshy land,residential land,bare rock and gravel land,among them cultivated land,sandy land and residential land areas increased obviously.(2) After 2000 some of the degraded land had been contained and the land quality was improving increasingly.(3) From 1987 to 2000,all the new added cultivated land came from forage land and wetland.Since 2000,cultivated land grew faster;the range of land reclamation had extended from quality forage land and wetland to low coverage grassland and some unused land.(4) High coverage grassland showed significantly degradation and reclamation was serious,their proportions occupied the reduced area by 85.84% and 11.51% respectively.(5) During the 18 years,the study area newly added sandy land by 20769.82 hm2,it was mainly from grassland.So the grassland was seriously sanded.