Identification of forest fire disturbances and spatiotemporal distribution patterns in the Greater Khingan Mountains based on long-term remote sensing imagery

Objective This study aims to investigate the spatiotemporal distribution patterns of wildfire disturbances and identify trends in forest fire dynamics, providing a scientific basis for preventing fires in high-risk areas and optimizing the allocation of fire prevention resources.

Method We applied the LandTrendr-RF two-step approach, time series analysis, and spatial statistical methods to detect wildfire-affected areas in the Greater Khingan Mountains. We analyzed interannual trends in wildfire disturbance area, explored its spatial distribution characteristics, and examined the distribution patterns of fire severity and recurrent fires in relation to topographic factors.

Result (1) From 1987 to 2022, the total wildfire disturbance area in the Greater Khingan Mountains exhibited a significant overall decline, without distinct stage characteristics. (2) Wildfire disturbances displayed a clustered pattern at spatial scales of 0–180 km. The high-density core region was located at the intersection of Oroqen Autonomous Banner, Genhe City, and Huma County in the central-eastern area, while low-density zones were found in the western and southern regions. The disturbance extent initially expanded outward, then gradually contracted, with the fire center shifting southward before partially returning northward. (3) Wildfire disturbances were concentrated on gentle and sloping terrains, with high-severity fires more likely to occur on sunlit (south-facing) slopes. Elevations between 400 and 800 m represented a fire-prone belt, and low-elevation areas showed significantly higher recurrence rates of secondary fires. Although steep slopes accounted for a small area, they exhibited a high proportion of severe fires.

Conclusion Wildfire patterns in the Greater Khingan Mountains are characterized by "southern concentration and northern dispersion, dominance on gentle and sunlit slopes, and concentrated risk at mid-elevations." We recommend prioritizing the deployment of fire prevention infrastructure in high-risk areas—particularly in Oroqen Autonomous Banner, Genhe City, and Huma County at the border of Inner Mongolia Autonomous Region and Heilongjiang Province—and enhancing fuel management strategies on sunlit slopes to improve the precision of wildfire prevention and control.