我国耕地生态安全评价及障碍因子诊断

耕地生态安全评价及障碍因子诊断是改善耕地生态系统状况、促进耕地可持续利用的重要基础。在界定耕地生态安全内涵的基础上，构建了基于PSR模型的评价指标体系，采用熵值法和障碍度模型，对我国耕地生态安全进行了评价。研究表明：（1）1996~2010年我国耕地生态安全水平总体不断提高，综合指数从0484 4增加到0626 9，安全等级经历了“临界安全-较安全”的演变历程；（2）压力指数总体上呈现下降趋势，状态指数和响应指数总体上呈现上升趋势；（3）长远来看，系统压力是影响耕地生态安全的首要因素，1996~2010年系统压力和系统状态的障碍度分别以年均533%和052%的速度增加，而系统响应的障碍度以年均802%的速度下降；（4）影响耕地生态安全的主要障碍因子包括单位耕地面积农药负荷、单位耕地面积化肥负荷、人均耕地面积、土地垦殖率、水土流失程度等。为了促进耕地生态安全水平不断提高，需要进一步转变经济发展方式，加强土地利用监督管理，降低经济增长对土地资源的过度消耗；大力发展绿色农业，合理施用农药、化肥；积极开展农村土地整治，加强高标准基本农田建设；加大环境治理力度，有效控制水土流失程度

EVALUATION ON CULTIVATED LAND ECOLOGICAL SECURITY BASED ON THE PSR MODEL AND DIAGNOSIS OF ITS OBSTACLE INDICATORS IN CHINA

As the most valuable land resources，cultivated land is very important to agricultural production，which has some functions，such as production，the landscape culture，ecosystem services and so on. Evaluation on cultivated land ecological security is greatly helpful for improving the state of cultivated land ecosystem and sustainable cultivated land use. On the basis of defining the meaning of cultivated land ecological security，the evaluation index system for cultivated land ecological security was constructed based on the PSR model，then an empirical analysis was conducted in China by entropy method and obstacle degree model. The results showed as follows.（1） The level of cultivated land ecological security in China had been gradually improved from 1996 to 2010，with the index increasing from 0.484 4 to 0.626 9. The degree of cultivated land ecological security in China generally experienced two stages，i.e.，criticality safety and Safer. （2） The pressure index generally showed a downward trend，while status index and response index showed a rise trend. （3） In the long run，the system pressure was found to be the major factor affecting cultivated land ecological security in China. The obstacle degree of system pressure and system status increased by an annual average of 5.33% and 0.52%，respectively，but the obstacle degree of system response decreased by an annual average of 8.02% in China. （4） The pesticide load per unit of cultivated land，fertilizer load per unit of cultivated land，per capita cultivated land，land reclamation rate，and extent of soil erosion were verified to be the key obstacle for further improvement of cultivated land ecological security in China. The cultivated land ecological security was continuously improved by further transformation of economic development mode，promoting the strategic adjustment of economic structure，optimizing the layout of industrial upgrading，strengthening supervision and management for land utilization，improving the degree of land resources market allocation，effectively increasing the land use intensity，reducing economic growth on excessive consumption for land resources，vigorously developing green agriculture，accelerating the agricultural science and technology innovation，rational application of pesticides and fertilizers，effectively reducing pollution for cultivated land resources，carrying out rural land consolidation，strengthening high standard basic farmland construction，increasing the amount of cultivated land，improving the quality of cultivated land，increasing the investment for environmental protection，increasing the intensity of environmental governance，effectively controlling soil erosion，and so on.