Causal analysis of heightened forest fire risk under climate warming-wetting in Northeast China since 2006

Climate change has exacerbated uncertainties in the evolution of bioclimatic environments and elevated the risks of ecological disasters across regions. A comprehensive understanding of forest fire risk, its correlation with climate change, and the driving factors underlying such risk evolution is critical for addressing potential forest fire risks in Northeast China under a warming climate. Using ERA5 climate reanalysis data and relevant bioclimatic/forest fire risk products from the European Centre for Medium-Range Weather Forecasts (ECMWF), this study analyzed the evolution of forest fire risk in Northeast China over 2006–2023. The results showed that over the past 18 years, the region experienced a temperature increase of 1.0 ℃ and a precipitation increase of 47 mm, indicating a "warming-wetting" climatic trend. Concurrently, the forest fire ignition and spread indices in Northeast China’s forests increased by 9.4% and 16.1%, respectively, relative to the 2006–2023 mean values. Notably, in the Changbai Mountain forest area, the increasing rates of these two indices reached 4.5 and 2.5 times the regional average, while the daily fire severity and danger indices rose by 5.6% and 10.2% (–41.1% and –1.3% for Northeast China’s forests as a whole). Despite the overall wetting trend in the region, a significant increase in forest fire risk was observed in Northeast China’s forests, with peak risks occurring in spring (accompanied by prominent increments from winter to spring). This phenomenon is attributed to reduced precipitation, rising temperatures, and enhanced wind speeds, which collectively induce a dry bioclimatic environment and an increase in compound hot-dry events. Although the forest fire risk index in Northeast China remains low, greater attention should be paid to winter-to-spring fire risk evolution in forest edge areas. Additionally, under a warming scenario, the Changbai Mountain area requires focused research on fire risk evolution and targeted prevention measures in future studies.