Abstract: A conceptual model of ecological risk assessment is built, which includes the following procedures: to determine the objectives of risk management, to analyze risk probability, to choose appropriate assessment methods, to characterize assessment results, and to make risk management. Ordos, the study area, is located in the farming-grazing transitional zone of northern China. On the basis of Landsat TM images, historical records, survey data and socio-economic statistical data, the authors make the regional ecological risk assessment of Ordos in 2000 and 2008 using the RS, GIS and SPSS. The stressors such as drought, flooding, pollution, strong wind, sandstorm, desertification and soil erosion, are selected as the risk sources. Also, the index system of regional ecological risk assessment is set up. The results are presented as follows. The spatial differentiation of ecological risk level is evident in Ordos. The regions with high risk distribute in the Kubuqi Desert, Waowusu Desert, and Zhungeer and so on, which is directly related to their adverse environmental background and economic activities like large-scale mining. In 2000, the regions with moderate or high risk level mainly lie in the Zhungeer, Dalate, the Kubuqi Desert in Hangjin, and the middle, north, and southwest of Wushen. In 2008, the risk of most areas is lower. However, there are some exceptions, for example, the areas such as the middle and southwest of Dalate Banner, the northwest of Dalate Banner which lies in the Kubuqi Desert and along Yellow River, take higher risk. Dynamically, the risk degree presents a downward trend from 2000 to 2008, which is due to the implementation of various measures concerning eco-environmental construction and restoration. To be specific, the risk of grass and desert ecosystems decreases significantly, so does the farmland and forest. However, the risk of water and urban and rural ecosystems increases.

Key words: regional ecological risk, conceptual model, assessment, Ordos

摘要： 建立了区域生态风险评价的概念模型, 包括区域生态风险管理目标确定、风险源分析、风险度量方法、风险计算及风险管理几个步骤, 构建了区域生态风险评价的指标体系。选择地处中国北方农牧交错带的鄂尔多斯市作为案例区, 针对其主要的风险源干旱、洪涝、病虫鼠害、污染、大风、沙尘暴、沙漠化和水土流失, 基于遥感资料、历史记录、调查数据和统计数据, 使用RS, GIS和SPSS技术, 对研究区2000年及2008年的区域生态风险进行研究。结果表明, 鄂尔多斯生态风险空间差异较为明显, 高风险区主要分布在库不齐沙漠、毛乌素沙地和准格尔旗等地, 与区域生态环境本底和大规模采矿等经济活动直接相关。2000年偏高及高风险度分布区主要是准格尔旗、达拉特旗、杭锦旗的库布齐沙漠地区、乌审旗的中部和北部以及西南角；2008年大部分区域的风险度较小, 高风险度仅在达拉特旗西北部处于黄河和库布齐沙漠的区域以及中部、西南角有零星分布。2008年整体的风险度较2000年有大幅降低, 与2000年后采取的一系列生态环境建设与恢复措施直接相关。其中, 广泛分布的草地和荒漠生态系统的风险度明显降低、农田和林地生态风险也在减小, 但水域和城镇遭受的生态风险却在增大。

关键词: 区域生态风险, 概念模型, 评价, 鄂尔多斯