Background Across boreal North America, fire is the primary forest disturbance. In recent years, concerns about overwintering fires in boreal forests have been growing. Overwintering fires smolder throughout winter and reappear in early spring in the subsequent fire season. Aims To investigate the spatial and temporal changes in reburned area from overwintering fires with 30 m spatial resolution satellite data. Methods We used long-term Landsat satellite observations to map reburned area from overwintering fires – areas that burned twice, first during the initial fire season, and a second time during the subsequent fire season – between 1986 and 2024 in the Taiga Plains in the Northwest Territories, Canada and Interior Boreal Alaska in Alaska, USA. Key results Our algorithm detected significantly more reburned area from overwintering fires compared to other satellite-based burned area products (P 0.05). The absolute increase in reburned area from overwintering fires related to the increase in total burned area (around 50% of explained variation), thus the fractional contribution of reburned area from overwintering fires remained around 1% of the annual burned area. Conclusions Our study detected more reburning from overwintering fires at Landsat resolution with no temporal change in the fractional contribution of overwintering fires to the total burned area between 1986 and 2024. Implications Our work provides new insights into when and where emerging overwintering fires occur in boreal North America.
Hessilt et al. (Mon,) studied this question.