Forecasting wildfire-induced declines in potential forest harvest levels across Québec

Wildfires are increasing in importance in many regions of the Canadian boreal forest and are an ongoing risk for forest management activities. We simulated the effects of fires on long-term harvest levels on the 59 forest management units of the province of Québec, Canada, for the 2020-2100 period. Different climate change pathways (stable, RCP 4.5 or 8.5) and salvage logging rates (20% or 70% of mature burned stands) were simulated. Changes in forest flammability due to climate change, species migration and forest management were also considered. Under stable climatic conditions, the decline in potential harvest levels due to fire, based on 50 simulations per scenario, ranged between 3 - 36% (mean = 12%) when high salvage logging rates were simulated, compared to 4 - 59% (mean = 21%) for low salvage rates. Climate change caused increases in burn rates between -3 and 39% for RCP 4.5, and between 33 and 69% for RCP 8.5 at the end of the 21st century. However, the effects of these modified burn rates on harvest levels did not differ substantially from those of baseline burn rates, probably because the projected burn rates were comparatively greater during the later part of the simulations (2070-2100), when their impacts on harvest rate calculations were limited. This study indicates that potential harvest levels calculated without considering wildfires are likely to be non-sustainable.