Developing a biodiversity–health–services nexus to reveal how external pressures influence ecosystems: Evidence from Sanjiangyuan National Park

The cascading relationships among biodiversity (BD), ecosystem health (EH), and ecosystem services (ES) are critical for understanding how external pressures, such as climate change and human activities, influence ecosystem processes. However, such relationships remain rarely explored. To address this, we developed a new BHS (biodiversity–health–services) nexus framework for Sanjiangyuan National Park (SNP), chosen for its pristine and complete ecosystems. This research integrates Generalized Convergent Cross Mapping, network analysis, structural equation modeling, and Zonation to examine the cascading relationships and response mechanisms of the ecosystem to external pressures. The results show significant bidirectional causal relationships among biodiversity, ecosystem health, and ecosystem services in SNP, with BD→EH→ES as the dominant pathway. The BHS nexus maintained a stable positive network structure, with ecosystem health as the key hub. Notably, climate change and human activities influence the BHS nexus primarily through biodiversity, affecting the system through the −BD−ES and −BD−EH−ES pathways. Climate change exerted a dominant negative effect, while the impact of human activities shifted from negative to positive after the implementation of the national park system. Spatial priority analysis identified overlaps between high-pressure areas and high-value BHS regions, leading to the development of targeted sustainable management strategies. This study emphasizes that focusing on biodiversity sensitivity and the central role of ecosystem health can facilitate precise ecosystem management. The framework enhances our understanding of the internal relationships and external driving mechanisms within the BHS nexus, providing scientific insights for ecosystem management in national parks located in similar ecologically sensitive regions.