Trends in wildfire burn severity across Canada, 1985 to 2015

Abstract

Burn severity is an important component of the fire regime that has not yet been fully characterized for the forests of Canada. The objectives of this study were to (i) create a Canada-wide geospatial database of burn severity for wildland fires across forested regions of Canada from 1985 to 2015, and (ii) use this database to evaluate seasonal and annual trends in burn severity across Canada and regionally using two different regional units (ecozones and Homogeneous Fire Regime zones). We developed the 30 m resolution geospatial Canadian Landsat Burn Severity (CanLaBS) product from Landsat imagery, using values of pre-fire to post-fire differences in normalized burn ratios (dNBRs) for nearly 60 Mha of area burned across Canada’s forests from 1985 to 2015, complemented with estimates of pre-fire forest composition, crown closure, and biomass. Our results suggest that burn severity is generally lower in spring fires than in summer ones nationally and in almost every regional unit. We found no consistent relationship between burn severity and annual area burned across ecozones. Finally, we observed a small but significant decrease in burn severity from 1985 to 2015 across Canada, although this is regionally variable. The CanLaBS database is publicly available at https://doi.org/10.23687/b1f61b7e-4ba6-4244-bc79-c1174f2f92cd .