Wildfire impacts on northern boreal forests

Print | PDF

Project Background

Climate warming and drying are leading to more severe wildfire seasons, a pattern that the NWT is experiencing first-hand. These fires threaten communities and infrastructure but also impact vast tracts of forested lands. In 2014, for example, 2.85 million hectares of forested lands burned; the devastating fire season of 2023 has exceeded this value already. Following the 2014 fires, widespread concerns were expressed by communities and governments about what the impacts of such a large fire event might be for forest recovery, wildlife habitat, and other components of ecosystem functioning and traditional livelihoods. To address this concern, we have developed a Territory-wide network of permanent sampling plots that allow us to understand the immediate effects of wildfire on forest recovery, wildlife forage availability, and carbon stocks and the longer-term recovery of these things with time after fire.

Outcomes

• Forests recover following these large fire events, but the composition is altered. Black spruce has shown declines while aspen and jack pine become more common in the landscape. These declines occur in the face of severe burning or where the fire free interval is short.

• Wildlife forage is differentially impacted by wildfire but caribou lichen, a forage species of particular concern takes on average 75 years to recover following fire.

• Carbon losses from these large fires are enormous. The 2014 fires produced 94Tg of carbon which is equivalent to half of the carbon uptake by all ecosystems across Canada. Carbon losses included old or legacy carbon, particularly where the fire-free interval was short.

Impacts

This work demonstrates the impacts of large fire years on the forests of the Northwest Territories.

• We have demonstrated that changing fire activity (more severe burning, shorter fire free intervals) leads to changes in forest composition, affecting many ecosystem functions including wildlife habitat.

• Similarly, deep burning and short fire free intervals lead to large carbon losses. These large fire years coupled with loss of old or legacy carbon reduce the carbon sink strength of NWT forests.

• Compositional shifts from spruce to aspen mean changes in the vegetation that recovers with notable negative impacts on caribou lichen biomass recovery. Shorter fire free intervals will also be detrimental for caribou lichen recovery given the long (75 year) recovery times.

Partners

• Government of the Northwest Territories
• Université Laval
• University of Colorado Boulder
• Northern Arizona University
• University of Alaska Fairbanks
• University of Victoria Wellington

More Information

https://forestecology.ca