Simulation of Urban Land Expansion Under Ecological Constraints in Harbin-Changchun Urban Agglomeration, China

Under the demand of urban expansion and the constraints of China's 'National Main Functional Area Planning' policy, urban agglomerations are facing with a huge contradiction between land utilization and ecological protection, especially for Harbin-Changchun urban agglomeration who owns a large number of land used for the protection of agricultural production and ecological function. To alleviate this contradiction and provide insight into future land use patterns under different ecological constraints' scenarios, we introduced the patch-based land use simulation (PLUS) model and simulated urban expansion of the Harbin-Changchun urban agglomeration. After verifying the accuracy of the simulation result in 2018, we predicted future urban expansion under the constraints of three different ecological scenarios in 2026. The morphological spatial pattern analysis (MSPA) method and minimum cumulative resistance (MCR) model were also introduced to identify different levels of ecological security pattern (ESP) as ecological constraints. The predicted result of the optimal protection (OP) scenario showed less proportion of water and forest than those of natural expansion (NE) and basic protection (BP) scenarios in 2026. The conclusions are that the PLUS model can improve the simulation accuracy at urban agglomeration scale compared with other cellular automata (CA) models, and the future urban expansion under OP scenario has the least threat to the ecosystem, while the expansion under the natural expansion (NE) scenario poses the greatest threat to the ecosystem. Combined with the MSPA and MCR methods, PLUS model can also be used in other spatial simulations of urban agglomerations under ecological constraints.