Quantifying the Drivers of Vegetation Resilience Gradient Effects Across Hierarchical Administrative Borders: A Case Study of the Beijing–Tianjin–Hebei Region

Understanding vegetation resilience gradient effects across hierarchical administrative borders is critical for cross-jurisdictional land management yet remains underexplored. This study integrates an AR(1) model with XGBoost-SHAP analysis to assess resilience and its drivers across provincial, municipal, and county borders in the Beijing–Tianjin–Hebei (BTH) region using NDVI data (2000–2025). The results show that (1) vegetation resilience across hierarchical border belts experienced an initial decline followed by recovery. A notable shift in resilience optimality was observed from city borders in 2005 to provincial borders by 2020. Gradient effects were stronger in northern city borders. The stable-fluctuating type dominated, followed by peak and valley types. (2) Precipitation, tree age, and altitude suppress gradient formation. Conversely, cross-boundary economic disparity, nighttime light differences, and land use composition tend to be associated with amplified gradient effects in a hierarchical manner: cropland and built-up expansion intensify gradients at provincial borders but reduce them at city borders, suggesting a potential role of governance coordination. (3) Based on these findings, a tiered governance framework is suggested—northern high-gradient provincial and city borders are proposed as priority areas for intensive interventions, while county borders (where gradient effects are weakest) may benefit from moderate, low-intensity interventions focused on maintaining land use continuity. At the provincial level, stronger inter-provincial coordination—through cross-boundary ecological compensation and harmonized environmental standards—may help mitigate gradient effects. Collectively, this study provides insights for cross-jurisdictional land governance in the BTH region and other analogous urban agglomerations.