中文摘要：

在PSR模型框架下，利用熵法确定权重，采用1986年Landsat TM和2000年ETM＋影像确定模型中的自然组分数据，结合社会经济统计数据，对生态安全过程进行景观格局判定，较好地得出了15年来甘肃中部地区生态安全的变化状况。研究表明：2000年甘肃中部地区生态安全状况整体较差，15年来，人类活动加速了自然组分的退化，逐步弱化了景观中的稳定成分，促进形成了异质性程度低、格局粗粒化、稳定性差的景观格局，其中，快速城市化、水资源减少和耕地、林地等重要土地资源的快速转化是整个地区生态安全状态弱化的主要原因。

英文摘要：

Using two sets of TM/ETM images acquired on July 31,1986 and May 23,2000 respestively, and the PSR model and information entropy to select the weight of the index, this paper gets the ecology security situation in the middle part of Gansu Province from 1986 to 2000. With the important factors, the landscape ecological index and land - use change, the paper obtains the change of the ecological security assessment in the middle part of the Gansu Province. In 2000, the ecology system is not safe in the middle part of Gansu Province; from 1986 to 2000, the ecological security had become a little worse although the main cities in the province such as Lanzhou, Baiyin and Dingxi had become better. In the recent 15 years, the nature factors had a little influence on the change of ecological security, but the human activities had taken a serious negative influence on the natural ecology, weakened the landscape factors＇ stability, accelerated the deterioration of landscape in study region.