Policy-Informed Land Use Optimization for Synergistic Food and Ecological Gains in an Urbanizing Watershed

Unsustainable land-use transitions in peri-urban watersheds threaten both food security and ecological integrity. While Patch-generating Land Use Simulation (PLUS) and Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) models for ecosystem service (ES) assessment are commonly integrated, limited studies have simultaneously (i) accounted for multiple real-world spatial policies (e.g., ecological redlines) as hard constraints, (ii) targeted a comprehensive suite of ESs, and (iii) explicitly pursued synergies without relying on large-scale land conversion. To address these gaps, we developed a spatially explicit framework that integrates the PLUS and InVEST models to simulate four land-use scenarios and assess six ESs—grain yield, water yield, nitrogen export, phosphorus export, soil conservation, and carbon sequestration—in the Yuqiao Reservoir watershed, China, during 1990–2030. Against a backdrop of historical declines in cropland/grassland and key ESs due to construction expansion (1990–2020), the novel Comprehensive Development scenario—implementing slope-adaptive management and riparian buffers—synergistically increases grain yield (+0.55%) and carbon sequestration (+1.10%) while drastically reducing phosphorus export (−10.86%). It demonstrates that synergistic gains can arise from strategic spatial reconfiguration within a stable land-use area, advancing a paradigm from area-centric to configuration-centric optimization. This provides a quantifiable methodological basis and actionable policy reference for land spatial optimization in similar water-source watersheds.