中文摘要：

科学评判生态退耕区农业土地利用可持续性的变化特征，对相关政策的完善具有重要的意义。本文以甘肃正宁县为案例区，从土地投入水平合理度、土地产出效益、环境支持力、政策补贴4组准则出发，选取了影响农业土地利用可持续性的15个指标，构建了基于1995—2010年时间序列数据的测算体系，并通过相对接近度法（TOPSIS），来多层次衡量农业土地利用的可持续性时序变化特征。最后采用层次聚类法，基于全部指标对研究年份进行聚类，进而区分研究区农业土地利用可持续性变化的时间节点。结果表明：①构建的土地投入水平合理度指数C（I）、土地产出效益指数C（D）、环境支持力指数C（E）和农业土地利用可持续性指数C（r）时序曲线都表现出明显的波动上升的趋势，c（丁）最大值为2002年的0．77，最小值为1995年的0．20；②通过层次聚类分析将正宁县退耕前后16年的农业土地利用可持续性特点划分为：1995—2002年的波动调整阶段、2003—2007年的稳定增长阶段和2008—2010年的巩固预警阶段。

英文摘要：

In ecological restoration regions in western China, local farmers increase agricultural materials to increase the yield per unit cropland, resulting in serious potential agricultural non-point source pollution. If this situation is not controlled, the function and effectiveness of ecological restoration in the same areas will decline and the sustainability of agricultural land use in western China will be subject to ecological fragility and environmental pollution. Here, we used Zhengning county in Gansu province as a case study and selected 15 indicators spanning input and output levels, environmental background and policy to characterize land use sustainability. To indicate the yearly change in sustainability elements, the modified technique for order preference by similarity to ideal solution （TOPSIS） method was put forward to build four sequential indices： input reasonable degree index C（I）; output benefit index C（O）; environmental capacity index C（E）; and total ecological coordination index C（T）. The hierarchical cluster method was used to classify years （1995-2010） based on the 15 indicators and define stages of land use sustainability change. We found that sequential lines of C（I）, C（O）, C（E） and C（T） showed obvious fluctuant characteristics. The instability was the result of many indicators, but the overall trend was increasing. The maximum value for C（T） was 0.77 in 2002, and the minimum value was 0.20 in 1995. Hierarchical clustering analysis showed that characteristics of land use sustainability before and after the implementation of ecological restoration in Zhengning from 1995 to 2010 was divided into three stages： adjustment stage （1995-2002）, stable growth phase （2003-2007） and consolidation warning phase （2008-2010）.