基于PSR模型的耕地生态安全物元分析评价

耕地生态安全评价是改善农田生态系统安全状况、促进耕地可持续利用的重要基础。针对多数综合评价研究中存在信息屏蔽和主观性的问题,在界定耕地生态安全内涵的基础上,构建了基于压力-状态-响应(PSR)模型的评价指标体系,采用物元分析方法和改进的熵值法对我国耕地生态安全进行评价。研究结果表明:(1)1996-2010年我国耕地生态安全水平不断提高,安全等级经历了"临界安全-较安全"的演变历程,但2010年"较安全"等级关联度很弱;(2)单位耕地化肥负荷、人均耕地面积、单位耕地农药负荷、土地垦殖率、水土流失程度等是耕地生态安全等级提升的关键制约因素。为了促进耕地生态安全等级不断提升,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。基于PSR模型的评价指标体系能更准确地反映农田生态系统各要素之间的关系,物元分析方法可以揭示单个评价指标的分异信息和综合评价结果的中间信息、挖掘耕地生态安全存在的具体问题,适合用于耕地生态安全的评价。

Evaluation on cultivated land ecological security based on the PSR model and matter element analysis

Evaluation on cultivated land ecological security is a significant foundation for improving the security of farmland ecosystems and the sustainable use of cultivated land. To solve the problem of asymmetric information and subjectivity in most integrated evaluations, the authors define the cultivated land ecological security, construct an evaluation index system based on the Pressure-State-Response (PSR) model, and then conduct an evaluation of the ecological security of cultivated land in China by the matter element analysis and the improved entropy method. The results show: (1) The ecological security of cultivated land in China was gradually improved from critically safe to safer from 1996 to 2010, but the correlation of "safer" was extremely weak in 2010; (2) Crucial constraints on the improvement of cultivated land ecological security include fertilizer load per unit of cultivated land, per capita cultivated land, pesticide load per unit of cultivated land, land reclamation rate, and soil erosion. For the cultivated land ecological security to be continuously improved, the economic development pattern should be transformed, land use supervision and management strengthened, and excessive consumption of land resources for economic growth reduced; green agriculture should be vigorously developed, pesticides and fertilizers applied only as needed; rural land consolidation and high-standard basic farmland construction should be strengthened, environmental protection intensified, and soil erosion effectively controlled. The evaluation index system based on the PSR model can accurately reflect the relationship between various elements of the farmland ecosystems, while the matter element analysis can reveal differentiation information of every single indicator and intermediate information of comprehensive evaluation, discovering specific problems in cultivated land ecological security. Therefore, the evaluation index system and the matter element analysis are suitable to assess the cultivated land ecological security.