Abstract: The implementation of ecological restoration of Beijing north-ring water system is of significance for the ecological degradation control and ecological services improvement of Beijing. In terms of the targets on ecological flow, water quality, and aquatic ecological conservation, five ecological restoration scenarios named as no-action scenario (S₀), pollution control scenario (S₁), integrative low-intensity ecological restoration scenario (S₂), integrative middleintensity ecological restoration scenario (S₃), and integrative highintensity ecological restoration scenario (S₄) were proposed. According to the results of model simulation, the optimal selection was conducted by using TOPSIS method. The scenarios S₂, S₃ and S₄ had 0.73, 0.81 and 0.93 of the approaching degrees to ideal point, respectively, with the ecological flow, water quality, and aquatic ecology complied with the required planning targets. They were finally selected as the recommended nearfuture, middleterm, and longterm implementation scenarios, respectively.

Key words: Photosynthesis, Eco-physiology, Urban forest