Objective With urban development and land use expansion, the structure and layout of various land use types are in dynamic change, and the fragmentation of ecological space becomes an important problem faced in the process of urbanization. The development of complex urban systems is highly influenced by social factors and human interference, and simple extrapolation and prediction of empirical knowledge can hardly predict future changes in urban land use. In view of this, it is recommended to use future land use simulation technology to simulate the changes of urban green space ecological network driven by multiple factors, so as to produce more reliable simulation results, thus improving the foresight and scientificity of urban planning work. Taking the central urban area of Shanghai as an example, this research conducts multi-scenario simulations of future land use, and measures the connectivity of green space ecological network under different scenarios, so as to provide a basis for optimizing urban ecological space in the future.
Methods The current land use data spanning the period from 2000 to 2020 are used as the base data, and raster data obtained are derived from 30 m×30 m rasters. Driving factors are screened, including population density, GDP distribution, distance to railroads, highways, and main roads, average annual climate/precipitation, etc., and the suitability probability of each type of land use is calculated. Taking 2000 as the base year, the land use scenario for the target year 2020 is simulated based on the PLUS model, and the spatial consistency between this simulation scenario and the actual status of land use in 2020 is compared in combination with the kappa coefficient and the overall accuracy. On the basis of satisfying the simulation accuracy, the land use changes in 2040 under different constraints are simulated, and the urban green space ecological network under multiple scenarios of future urban development is extracted. In addition, morphological spatial pattern analysis (MSPA) and functional connectivity measurement index analysis are implemented to explore the differences in structural connectivity and functional connectivity of urban green space ecological network under different scenarios in the future.
Results 1) During the period from 2000 to 2020, within the central urban area of Shanghai, the area of green space decreases most significantly, indicating that the rapid urbanization process has disturbed the city’s green ecological network to a great extent. In 2040, the area of green space will decrease to different extents under the three land use simulation scenarios, with the decay rate of green space under the ecological conservation and development scenario being effectively controlled. 2) The ecological conservation and development scenario provides good protection for the ecological sources of green space, and the overall patch fragmentation is mitigated, with the area of its bridging and traffic circle categories being significantly higher than that of the natural development scenario and the economic priority development scenario, which indicates that under the ecological conservation and development scenario, the ecological network of the green space has a stronger corridor connectivity, and is able to effectively improve the diffusion of species and the flow of energy between the ecological sources. 3) Under the multiple simulation scenarios targeting 2040, the spatial distribution and importance of key patches under different development scenarios of green space ecological network are basically the same, and such patches typically have a better ecological substrate, so they should be especially protected in future urban development; the patches with higher delta probability of connectivity (dPC) indicate that they are more important for future connectivity of green space ecological network, but they may have poor connectivity at present, so they can be used as potential source patches of green space ecological network for integrated planning.
Conclusion Compared to other scenarios, the decay rate of green space under the ecological conservation and development scenario targeting 2040 has been effectively controlled. In terms of structural connectivity (physical linkage), the green space ecological network has great corridor connectivity and stable network structure under the ecological conservation and development scenario. In terms of functional connectivity, important patches are crucial to the structural stability and socio-ecological functioning of the ecological network. Considering that the coordinated development of the economy and ecology is a long-term process, there is a long way to go to maintain the long-term ecological health of urban centers through policy regulation and planning guidance. In future urban construction, policy regulation and planning can guide the optimization of urban ecological space and maintain the healthy development of urban green space ecological network.
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