1996—2005年北京城市生态质量动态

从生态要素、生态过程、生态功能和生态问题4个主题出发，构建了包含16个指标的北京城市生态质量评价指标体系，并分别采用熵权法、最差状态法和最佳状态法对指标进行赋权，通过加权平均法构建了北京城市生态要素指数（EEI）、生态过程指数（EPI）、生态功能指数（EFI）、生态问题指数（EDI）和综合生态质量指数（CEI），用以评价1996—2005年北京城市生态质量动态变化.结果表明：研究期间，北京城市EEI无明显改善，持续维持在远离理想点的水平；EPI和EFI改善显著，由1996年的远离理想点到2005年接近于理想点的水平；EDI的年度波动较大，普遍远离理想点；CEI得到持续改善，但离理想点依然有一定距离.当人均国内生产总值（GDP）小于3 000美元时，EPI、EFI和CEI随GDP的增长而快速增大，改善显著，当人均GDP超过3 000美元后，EPI、EFI和CEI随GDP增长而增大的速度减慢；EEI和EDI受人均GDP的影响较小，主要受限于自然条件及全球和区域环境的变化.

Ecological quality of Beijing urban area from 1996 to 2005.

From the aspects of four ecological themes, i.e., ecological element, ecological process, ecological function and ecological destruction, an indicator framework including 16 indicators was developed to make an integrated assessment on the ecological quality of Beijing urban area. The weights of the indicators were determined by the methods of entropy weight, optimal state weight, and worst state weight, and the ecological element index (EEI), ecological process index (EPI), ecological function index (EFI), ecological destruction index (EDI), and composite ecological index (CEI) were computed by a weighted sum method and served as effective tools for analyzing the evolvement of the ecological quality of Beijing urban area from 1996 to 2005. The results showed that during the period of 1996-2005, the EEI of Beijing urban area did not display visible improvement and maintained a low level, far from the ideal state. The EPI and EFI increased dramatically, and approached to the ideal state in 2005. The EDI fluctuated within a low level, far from ideal state, and did not show an evolutionary trend. The CEI improved year after year, but was still low and did not reach the ideal state. The EPI, EFI, and CEI increased rapidly with economic development when the GDP per capita was less than US $ 3,000, but the decrease was decelerated after the GDP exceeded US $ 3,000. The EEI and EDI were less affected by economic development, but mainly restrained by the natural conditions and global and regional eco-environmental evolvement.