基于熵理论的城市生态系统服务流定量评估——以北京市为例

量化评价生态系统的服务功能是合理开发生态资源、实现可持续发展的重要前提.生态系统服务流能够为生态系统服务功能的量化评估提供解决方案.本文以四大生态系统服务类型为框架,构建了城市生态系统服务流评估体系;将生态系统服务流重新分类,引入熵理论,对指标及系统无序度、发展演变方向进行定量评价;并以北京市为研究对象,选择24个因子开展案例研究.结果表明:2004—2015年间,北京城市生态系统服务总熵值为0.794,总熵流为-0.024,系统无序度较大,濒临非健康状态;系统熵值3次取得极值,3个变化周期内系统熵值的年平均变化幅度逐渐增大,说明人为活动对城市生态系统干预强度增大;2007年熵流达到最小值,生态环境质量最高;北京市常住人口总数与城市生态系统熵流拟合函数的决定系数为0.921,说明人口数量与城市生态环境状态有很强的相关性.

Quantitative assessment of urban ecosystem services flow based on entropy theory: A case study of Beijing,China.

Quantitative evaluation of ecosystem service is a primary premise for rational resources exploitation and sustainable development. Examining ecosystem services flow provides a scientific method to quantity ecosystem services. We built an assessment indicator system based on land cover/land use under the framework of four types of ecosystem services. The types of ecosystem services flow were reclassified. Using entropy theory, disorder degree and developing trend of indicators and urban ecosystem were quantitatively assessed. Beijing was chosen as the study area, and twenty-four indicators were selected for evaluation. The results showed that the entropy value of Beijing urban ecosystem during 2004 to 2015 was 0.794 and the entropy flow was -0.024, suggesting a large disordered degree and near verge of non-health. The system got maximum values for three times, while the mean annual variation of the system entropy value increased gradually in three periods, indicating that human activities had negative effects on urban ecosystem. Entropy flow reached minimum value in 2007, implying the environmental quality was the best in 2007. The determination coefficient for the fitting function of total permanent population in Beijing and urban ecosystem entropy flow was 0.921, indicating that urban ecosystem health was highly correlated with total permanent population.