中文摘要：

本文以锡林浩特市和阿巴嘎旗境内30年来的植被变化为例,利用3S技术结合景观生态学的方法分析了该区70年代、80年代和90年代植被群落变化的特点。结果表明：在70年代末到80年代末研究区中群落类型和面积变化较大,新增加了两个类型,退化类型的面积增加较多。80年代末到本世纪初植被类型基本未变,但面积发生了较大的变化,特别是轻度退化类型的面积减少较明显,重度退化类型面积在不断的增加。选取4个景观指数的分析结果表明：景观多样性、景观破碎化和景观均匀度指数增加显著,植被格局变化强烈。分析其退化的原因可知：在草原植被一直以退化的方向发展的同时,决定草原群落结构的降雨量却呈现出明显的年代际变化,可见并不是影响草原退化的主导因素,而通过分析研究区近30年来牲畜的头数变化,却是直线上升的趋势,因此可以看出放牧对草原植被的变化起着决定性的因素。

英文摘要：

　In this paper,the vegetation communities change characteristics over the past 30 years were studied by division into three period（the 1970s,1980s and 1990s）in Xilinhot City and Abaga Country.The RS,GIS technology and landscape ecology analysis methods were used in the research.The following preliminary conclusions were got： From the late 1970s to the late 1980s,there had been great changes in vegetation.Two new types of communities in the study area had been added,the area of heavy degraded grades had been increased dramatically.From the late 1980s to the beginning of this century,the vegetation types changed little but the area changed greatly.The area of mild degraded type reduced obviously,but the area of heavy degraded type increased continually.The analysis of four landscape indexes showed that the landscape diversity,broken and evenness were increasing dramatically and vegetation patterns also greatly changed in recent 30 years.The analysis of the causes of its degradation revealed that while the steppe vegetation degraded,rainfall was not the dominant factor,grazing played a decisive factor in the changes of steppe vegetation.