Global divergence and spatial strategies in national park-City proximity thresholds

Whether national parks (NPs) should be located in wilderness areas or near cities has long been central to debates over ecological conservation and social well-being. Previous studies have mainly examined the impacts of urban expansion on parks and species, while little attention has been paid to how proactive NP siting shapes NP–city distance (NCD) or to the quantitative thresholds needed to balance conservation and use. To address these gaps, we developed the first global geospatial database of 3129 NPs across 233 countries and territories from 1872 to 2024. Based on coupled human–natural systems theory, we proposed an “NP–City synergistic development threshold” model. By integrating geospatial analysis, random forest modeling, and complex regression, and combining historical NP development stages with geographic endowments, we identified the dynamic role of NP–City distance in ecological–social system coupling and the thresholds linking species conservation with public leisure well-being (PLW). The results show that: (1) Mean global NCD declined by 22.4%, from 169.77 km in the pioneering stage to 131.75 km in the globalization-rewriting stage, indicating a shift from ecological isolation toward human–nature coordination; (2) An NCD–NP species diversity (NSD)–PLW framework was established, with a global turning point of 467.29 km. Tropical regions require NCD ≥ 600 km to maintain primary ecosystem integrity, whereas temperate regions can achieve high NSD–PLW compatibility at NCD < 100 km; and (3) A “functional compatibility service-efficiency curve” was proposed, showing that adaptive management at intermediate NCDs can improve compatibility between conservation and use. This study reveals the threshold effects of NCD on global NSD conservation from a proactive siting perspective and provides a spatial decision-making framework for the biogeographically adaptive implementation of the Convention on Biological Diversity's “30 × 30” target.