Large-Scale Spatio-Temporal Patterns of Burned Areas and Fire-Driven Mortality in Boreal Forests (North America)

Due to climate effects and human influences, wildfire regimes in boreal forests are changing, with noticeable ecological consequences shortening the fire return interval and increasing forest tree mortality. However, our understanding of the spatio-temporal patterns of fire-induced mortality in boreal forests remains limited, as research has predominantly focused on Mediterranean and tropical forests. In this study, we used satellite observations to study the spatial and temporal variability in burned area and forest mortality due to wildfires in North America (Alaska and Canada) over an 18-year period (2003 to 2020). The study has shown average values of burned area and forest mortality close to 8000 km2/yr and 40%, respectively. Burning and tree loss are mainly concentrated between May and September with a corresponding temporal trend in the occurrence of forest fires and high mortality. Large-scale forest fires were primarily concentrated in Central Canada, which however did not show the highest forest mortality (in contrast, recorded in Northern Canada). A correlation analysis based on general linear models showed that fire size and duration, but not the burned area, had significant effects on post-fire forest mortality. Overall, the study shed light on the most sensitive forest areas and time period to the detrimental effects of forest wildfire in boreal forests of North America.