People passionate about nature

The Ecology of Wildfires

How Wildfires Impact the Boreal Forest in Manitoba

by: Lynsay Perkins

More than fifteen years ago a bear started a wildfire in Alberta. His accomplice? Human activity. It was a very rare and strange case where a bear climbed a hydro pole, and while tampering with the power lines caused enough sparks to create a forest fire. Of course most wildfires aren’t caused by curious bears, but this incident illustrates the point that we can’t always jump to conclusions about how humans impact the natural world.

“Humans can cause a large fire. There’s no doubt about that” says Dr. Brian Amiro (University of Manitoba), who has been studying land resource science (agrometeorology) since the early 1980s. “Usually a lot of really large fires are naturally caused.”

When a wildfire passes dangerously close to homes and cabins, or when it devastates lives and families, a wildfire is scary and destructive. But when you look at wildfire’s non-human, ecological impacts it’s important to remember fire has always been around, and has always been an integral part of the forest ecosystem.

Amiro goes on to say humans do cause the majority of forest fires, but he reiterates that fire is important for forest regeneration and is a very natural part of the Canadian boreal forest. “The average age of the boreal forest is only 100 years old,” he says. "Woodpeckers and insects, for example, like new forest. Pine Martens and squirrels, on the other hand, really need mature forest." The key to forest diversity is diversity of forest age – fire also helps achieve that.

“We need to have diverse age structures,” says Amiro. “We don’t know what the optimum mix is, just that a mix is needed. If we start getting into too many fires, if we started getting a fire in an area every 30 years, that would change the ecosystem.” Amiro says he’s not sure if we’re there just yet.

Currently between one million and eight million hectares of forest burns every year in the boreal, but that varies greatly from year to year and region to region. Amiro says looking at a single year, like 2016 alone, can’t give you accurate indications of wildfire trends. “The projections that we have made for the boreal forest in Canada into the future caused by warming temperatures, is that there will be an increase in the area burned.”  

Amiro’s current research is trying to figure out how warming temperatures affect the amount of carbon a forest produces and absorbs, which is known as its carbon load. “If we were not having any changes in our climate our carbon loads would be neutral,” he says. “Our climate is changing and we are trying to figure out whether that changes our overall carbon loads.”

During a fire a forest loses carbon into the atmosphere, and as the mature trees decompose they release carbon as well. “You get a net carbon loss for the first ten years or so after a fire. By about twenty years that flips around so the forest is taking up carbon,” Amiro says.

According to Amiro a forest between 20 – 80 years old is the best at storing carbon. Older than 80 years and it becomes neutral. But exactly how warming temperatures and an increase in the area of forest burned will affect our climate is difficult to pinpoint. “We’re trying to understand the dynamics of the forest and it’s really complex,” he says.


In the meantime you can help reduce the risk of human-caused wildfires by educating yourself and your family and friends about fire prevention. For more information about wildfire prevention visit the Government of Manitoba FireSmart website at