Disparities in wildfire regimes across China's borders: Policy-driven asymmetries in fire frequency, intensity and impact

Border zones between countries are among the world regions with large spatial variability in wildfires. However, our understanding of fire regimes in these areas, particularly quantitative assessments of cross-border fire risk, remains limited. This study examines fire regimes and their driving factors along China's extensive land borders, which encompass the world's longest border and the second-highest number of neighboring countries. Utilizing Moderate Resolution Imaging Spectroradiomete satellite products, we analyzed fire occurrence (fire count), intensity (fire radiative power), and impact (burned area) within 50-km buffer zones on both sides of the border, their relationships with vegetation, and the statistical differences across borders. The results indicate that approximately 10% of China's land border areas face threats from cross-border fires, primarily originating from Russia, Mongolia, and Laos. The wildfire metrics in neighboring countries—notably the fire count and cumulative FRP in Russia, Myanmar, and Laos and the total burned area in Mongolia and Russia—were significantly greater than those in China. However, the differences in vegetation between inside and outside the borders were not significant. The results suggest that the fire disparities were primarily driven by divergent fire management policies and resource allocation. We argue that effective mitigation of transboundary fire risk requires an integrated approach that combines regional governance, targeted prevention measures, and strengthened international cooperation. Quantifying policy-driven disparities in fire regimes provides a critical baseline for coordinated management in global border hotspots. • Policy divergence - China's strict suppression vs neighbors' permissive use; • Foreign-side FN, FRP, BA: 7.62×, 9.89×, 7.40× Chinese-side values; • About 10% of China’s border has experienced cross-border fires; • Main fire-source regions: Russia, Mongolia, Myanmar, and Laos; • Bilateral 50-km buffer framework enables spatially explicit comparison.