Optimizing land-use for biodiversity conservation and wind prevention and sand fixation in northern China's agro-pastoral ecotone

The Northern China's agro-pastoral ecotone is a critical ecological barrier for central and eastern China but is also highly ecologically vulnerable. Competition between cultivated land and grassland, together with climatic variability, has accelerated land degradation, soil erosion, and biodiversity loss. Optimizing land-use configurations is essential for enhancing ecological functions, yet practical multi-objective optimization remains limited in this region. This study examined cultivated land–grassland dynamics between 2000 and 2020 and developed an integrated optimization framework combining the Nondominated Sorting Genetic Algorithm II (NSGA-II) and the Future Land Use Simulation (FLUS) model to evaluate three representative land-use scenarios with different trade-offs between biodiversity conservation and wind prevention and sand fixation (WPSF). The results showed that reciprocal conversions between cultivated land and grassland dominated land-use changes during 2000–2020 and closely corresponded to shifts in the 400 mm precipitation isohyet. All three optimized scenarios improved species richness-based biodiversity and WPSF benefits relative to the 2020 baseline, with biodiversity gains primarily linked to forest expansion and WPSF gains to grassland expansion. More importantly, spatial optimization exhibited substantially greater potential for enhancing WPSF than for biodiversity across the three scenarios, with >98.5% of the study area showing changes in WPSF compared with ∼44% showing changes in biodiversity. These findings imply that, to enhance WPSF, grassland conservation and restoration should be prioritized, whereas biodiversity conservation requires broader ecological restoration and governance strategies beyond spatial optimization. Beyond these regional implications, the proposed framework offers a transferable approach to support multi-objective land-use planning across agro-pastoral ecotones.