Abstract: Objective This study analyzed the spatiotemporal distribution dynamics of lightning-caused fires in the Altai Mountain forest region from 2000 to 2022. By exploring the activity patterns of lightning-caused fires, this research aims to facilitate local lightning-caused fire prediction and prevention. It is of great significance for the protection of state-owned forest assets and the maintenance of forest security.Method Based on the historical data of lightning-caused fires in Altai Mountains forest region in Xinjiang from 2000 to 2022, the temporal distribution characteristics and dynamics of lightning-caused fires were analyzed. By combining the digital elevation model (DEM) of the study area, the spatial information of corresponding lightning-caused fires was extracted by ArcGIS software, and its spatial characteristics and dynamics were analyzed.Result The inter-annual dynamics of lightning-caused fires in the Altai Mountains forest region of Xinjiang from 2000 to 2022 show an increase in active fire years and a decrease in inactive fire years after 2012 compared to before 2012. Active years are characterized by a higher number of lightning-caused fires and more active fire days, while inactive years have fewer fires and active days. The earliest occurrence of lightning-caused fires is in April, and the latest in September, with the majority (95%) concentrated in June to August. July experiences the highest number of fires and the largest burned area, while August has the highest firefighting costs and the greatest number of personnel mobilized. The Habahe area has the highest number of lightning-caused fires and the most personnel mobilized, Altay has the largest burned area, and Burqin has the highest firefighting costs. The distribution of fire numbers with respect to altitude is approximately normal, peaking between 1 800-2 000 m, with the 1 400-1 600 m range having the highest firefighting costs and the most personnel mobilized. Slope terrains have a higher number of lightning-caused fires, greater firefighting difficulty, and larger burned areas, with over 50% of fires occurring on slopes between 0°-20°. The steepest slopes, between 70°-80°, incur the highest firefighting costs. The eastern slopes have the highest number of fires and personnel mobilized, while the southeastern slopes have the largest burned area and the most firefighting costs.Conclusion After 2012, lightning-caused fires became significantly more active. This is evidenced by an increase in the number of active years and an extension of the average active period of lightning-caused fires compared to the period before 2012, although the number of inactive years of lightning-caused fires decreased after 2012, the average active period of lightning-caused fires in these inactive years was significantly shortened. Overall, the inter-annual fluctuations in the activity level of lightning-caused fires became stronger. Lightning-caused fires in specific longitudes, latitudes, altitudes, slopes, and aspects exhibit a clustered distribution. Post-2012, a notably higher occurrence of lightning-caused fires is observed within the range of 48.4°N to 48.7°N and 86.5°E to 87°E. Overall, there is a trend of migration from lower to higher altitudes and from steeper to milder slopes, with a preference for concentration on the eastern slopes.

Key words: Altai Mountains forest region, lightning-caused fires, spatiotemporal distribution, dynamic characteristics