Application of CITYgreen5.0 model to tender appraisement of small-scale green-space designs

Developed by the American Forests, CITYgreen5.0 model has been widely applied to urban forestry research and has played an important role in analyzing quantitatively the ecological benefits produced by varied green-space ecosystems. One of the functions of this model is to evaluate quickly and objectively on parts of the ecological benefits possibly produced by different design schemes for the same small-scale green-space project before the establishment. A comparative analysis was conducted by modeling partial ecological benefits potentially produced by green-spaces of two different design schemes for the same roof garden of Chuangfushidai-Junjingyuan in Shenzhen, given the growth status of plants both immediately after the establishment and 20 years later. Meanwhile, the project costs for each design scheme were also taken into consideration. The results showed that scheme II, mainly designed with a natural style of plant disposition, had a better greenery structure than that of scheme I, which was basically designed with a regular style of plant disposition. The estimated value of the partial ecological benefits produced by scheme II was larger than that of scheme I and the benefit-cost ratio of scheme II was more rational. It was suggested that scheme II be put into practice.