Fire Regimes in North American Boreal Forests from 1980 to 2024

Purpose of Review As anthropogenic climate change is expected to increase fire activity in North America’s (NA) boreal forests, the need for a deeper and timely understanding of regional fire regimes at scale is urgent. This review presents 1980–2024 spatial distributions of fire regime metrics in boreal forests of Canada and Alaska. Our aim was to show the spatial variability of fire regime metrics across homogeneous fire regime units. We also explored relationships between fire-regime metrics and assessed temporal trends at larger spatial scales. Recent Findings There are disagreements with regards to the direction of temporal and spatial trends across regions in NA boreal forests. A debate also remains regarding the importance of climatic control relative to biomass continuity on fire size and burn rates in these forests. Summary High interannual and intra-regional spatial variability characterised fire regimes in NA boreal forests, challenging the detection of temporal trends. Nevertheless, we found that fire occurrence and other fire regime metrics intensified significantly in western boreal regions, and the peak of the fire season shifted earlier in western Canada, consistent with increasing climatic influence in these regions. In eastern Canada, no significant increases were detected, suggesting that vegetation and precipitation may still buffer the effects of warming, though this may evolve as drought frequency increases. The share of human-caused fires decreased in Canada over the study period, suggesting that prevention and suppression efforts may have had some effect. Further studies investigating direct effects of climate and fuel continuity on fire regimes are necessary for improved forecasting of fire activity under changing conditions.