Urban growth simulation guided by ecological constraints in Beijing city: Methods and implications for spatial planning.

An ecologically constrained and scenario oriented urban growth simulation provides an effective means to address and mitigate ecological impacts resulting from urban expansion. However, current urban growth simulations usually set ecological indicators as explanatory variables in the model, while ignoring the trade-off relationship between the requirement for additional urban space and the prevention of ecological loss. In this study, ecological loss was set as a constraint parallel to the urban growth simulation indicator system. The Minimum losses of key ecosystem functions were set as constraints in order to realize optimized urban growth pattern. Taking Beijing's urban growth from 2000 to 2010 as a case, we proposed an optimized coupling model with ecological loss as a constraint in urban growth simulation. The results showed a 22.96% reduction in the total amount of ecological loss under the ecological constraint. According to the urban growth simulation, the "constant growth scenario" had the least ecological loss. Moreover, a combination of multiple ecosystem functions is required for describing the ecological constraint. We suggest that ecological constraint in an urban growth simulation model could be an effective policy tool to plan urban expansion and provide more accurate support for the formulation of spatial planning.