吉林省西部草地退化严重,研究该区草地时空演变对其畜牧业及生态环境可持续发展具有重要意义。利用1980、1995、2000年三期遥感影像,在RS与GIS支持下,解译提取该区草地信息,分析其时空变化。结果表明:①20年来,草地面积减少40.70%,尤其高覆盖度草地,净减少率达51.96%;②1980至1995年,从动态度可以看出高覆盖度草地对草地整体变化影响较大;1995至2000年,总动态度和高、中覆盖度草地动态度接近,这两种草地类型对草地整体变化影响较大;③草地主要转化为耕地和盐碱地,转移面积分别达475799.43hm²和303182.06hm²;④20年来,各类型草地重心向东北方向偏移,不同阶段各类型草地重心偏移表现出无规律性、多向性。自然因素对该区草地退化起到一定的驱动作用,人类活动干扰则是主要驱动力。

Grassland had heavily degraded in west Jilin province during 1980-2000,and it is of great importance to the sustainable development of stockbreeding and eco-environment through study ing on spatio-temporal dynamic change of grassland in this region.By using three-period(1980,1995,2000)remote sensing images and with the support of RS and GIS,spatial information of grassland landscape in west Jilin province in the past 20 years is interpreted and extracted,dynamic spatio-temporal change of grassland landscape patterns of Jilin province is analyzed.The results show:(1)In the past 20 years,40.70% of the grassland decreased,and grassland degradation is serious,especially for high coverage grassland with a net decreasing rate of 51.96%.(2)From 1980 to 1995,the total dynamic degree of grassland is accordant with the dynamic degree of high coverage grassland,so high coverage grassland has a strong effect on change of the whole grassland.During 1995-2000,both dynamic degree of various grasslands and total dynamic degree are negative,the speed of low coverage grassland degradation is the fastest,the total dynamic degree approximates the dynamic degree of high coverage grassland and moderate coverage grassland,and the two types of grasslands heavily affect change of the whole grassland.(3)Grassland is mainly converted into cropland and saline-alkalized land,the converted area reaches 475 799.43hm² and 303 182.06hm² respectively.(4)In the last 20 years,the center of gravity of all kinds of grasslands moved towards northeast direction,and in different phases,the change of center of gravity of each kind of grassland is irregular and multi-directional.As far as grassland degradation in the study area is concerned,natural factor takes certain driving action,but human actions are the dominating driving power.