Future fire risk and the greenhouse gas mitigation potential of forest rehabilitation in British Columbia, Canada

Increased forest fires in the future will create opportunities to undertake salvage logging and replanting activities with the potential to reduce greenhouse gas (GHG) emissions relative to a 'do nothing' scenario that relies on natural regeneration. Salvage logging of fire-killed wood will generate additional useful products for society while replanting will provide opportunities to establish seedlings with genetic gain and increased climate resilience. In British Columbia, Canada, our study showed that cumulative net GHG benefit from these rehabilitation activities on about 14 % of the area burned ranges from -32 to-79 MtCO2e in 2070, but cumulative net GHG reduction benefits are not realized for 23 to 31 years due to the emissions debt that is incurred from harvest wood product emissions and residue management. Scenarios were modelled using the Generic Carbon Budget Model (GCBM) that tracked carbon in the forest and a harvested wood products model that tracked the fate of C and the substitution benefits achieved through wood use, both developed by the Canadian Forest Service. Results were evaluated across 100 simulations of future fire, developed using a log-normal model fit to historic fire events and an assumption of linearly increased area annually burned by 2070 to double the average of the period 1950 to 2018. Our results suggest that mitigation efforts might be better directed at reducing wildfire risks and emissions in the first place, rather than rehabilitating post-fire outcomes.

Automated summary

Increased forest fires in the future present opportunities for salvage logging and replanting, which can reduce greenhouse gas emissions compared to doing nothing and relying on natural regeneration. Salvage logging can produce useful products for society, while replanting can establish seedlings with genetic gain and increased climate resilience. However, the net greenhouse gas reduction benefits are not realized for several decades due to emissions from harvesting wood products. Mitigation efforts should focus on reducing wildfire risks and emissions in the first place, rather than rehabilitating post-fire outcomes.