An Ecological Risk Assessment of the Dianchi Basin Based on Multi-Scenario Land Use Change Under the Constraint of an Ecological Defense Zone

Ecological risk evaluation is a prerequisite for the rational allocation of land resources, which is of great significance for safeguarding ecosystem integrity and achieving ecological risk prevention and control. However, existing research lacks analysis of the ecosystem state after land use simulation within the restricted conversion zone, making it impossible to determine whether ecological risks have been mitigated under these constraints. Therefore, we selected the Dianchi basin as the study area, extracted the ecological defense zone as the restricted conversion zone, and used the PLUS (Patch-generating Land Use Simulation) model to simulate land use for 2030 under multiple scenarios. We then evaluated ecological risks based on landscape pattern indices, and analyzed ecological risks under multiple scenarios with and without the restricted conversion zone. By comparing ecological risks across scenarios with and without constraints, we clarified the critical role of ecological risk evaluation in the rational allocation of land resources. The results show the following: (1) The ecological defense zone was obtained by overlaying no-development zones (such as forest parks and nature reserves), areas of extreme importance in the evaluation of water resource protection, soil and water conservation, and biodiversity, as well as areas of extreme importance in the evaluation of soil and water erosion and rocky desertification sensitivity. (2) Cultivated land and woodland cover significant portions of the Dianchi basin. Overall, ecological risk deterioration was more pronounced in the economic scenario (ES), while the ecological scenario (PS) exhibited lower ecological risk compared to the natural scenario (NS). (3) After importing the ecological defense zone into the PLUS model as the restricted conversion zone for land use simulation, ecological risks in all scenarios showed a trend of improvement. The improvement trend was strongest in the NS, followed by the PS, and weakest in the ES. The results of this study can help to identify the most suitable land use planning model and provide a more effective strategy for ecological risk prevention and control.