Multi-scenario simulation and ecological risk analysis of land use based on the PLUS model: A case study of Nanjing

With the expansion of economic activities in cities, the function of the urban system is complex and the ecological environment is destructed gradually. Urban planning is one of the important means to solve the above issues. In order to make the city develop sustainably through urban planning, scientific prediction and assessment of future ecological risks under different scenarios are the basis for all measures. This paper uses the PLUS model to simulate the land use data of Nanjing in 2025 under four scenarios that are Business As Usual (BAU), Rapid Economic Development (RED), Ecological Land Protection (ELP), and Ecological and Economic Balance (EEB). Then, the changes in various types of land and land transfer under each scenario are analyzed. Moreover, the assessment index considering urban expansion pressure, landscape ecological risk, grain reserve pressure, and ecological degradation pressure is used to analyze the ecological risk of land use under each scenario. The study found that the expansion intensity of built-up land is relatively strong under the RED scenario, followed by the EEB scenario, while the proportion of land with high ecological benefits such as woodland and grassland is higher under the ELP and EEB scenarios. The overall ecological risk level of the city under the ELP scenario is lowest, while the ecological risk under the RED scenario is highest. Therefore, in the region with a high population density and concentrated built-up land, attention should be paid to the protection of the ecological environment, and large-scale built-up land should be avoided by building ecological corridors. The ecological risk of the EEB scenario in the local area is lower than that of the ELP scenario. Therefore, due to the diversity of each municipal district of Nanjing city, individualized planning should be carried out according to the regional characteristics.