Spatiotemporal Dynamics and Future Trajectories of Coupling Coordination Between Net Ecosystem Productivity and Human Activity Intensity: A Case Study of the Zhangjiakou–Chengde Region, Northern China

Understanding the coordination between regional carbon sequestration and human activities is essential for achieving ecological sustainability and carbon neutrality. This study explored the spatiotemporal evolution, driving mechanisms, and sustainability of net ecosystem productivity (NEP) and human activity intensity (HAI) in the Zhangjiakou–Chengde (ZC) region of northern China from 2000 to 2023. NEP and HAI were integrated through a coupling coordination framework to assess their dynamic balance and relative development. Results show that the coordination between carbon sinks and human activities has improved continuously over the past two decades, shifting from human-dominated imbalance to a more synergistic pattern. Spatially, higher coordination levels were concentrated in forested mountain areas, while agricultural and transitional zones exhibited instability or lagging development. Land use regulation, vegetation recovery, and terrain conditions were identified as the primary factors shaping this pattern, with interaction effects amplifying spatial disparities. Trend analysis suggests that northeastern and eastern regions will likely sustain their positive trajectories, whereas the agro-pastoral transition belt remains vulnerable. These findings deepen understanding of carbon–human interactions in fragile ecosystems and provide scientific evidence for differentiated land management, ecological restoration, and carbon neutrality planning in northern China and similar regions worldwide.