Canada’s vast boreal forests are changing due to climate change. But not all hope is lost | TBEN News

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TBEN Alberta and Saskatchewan team up for a new pilot series on weather and climate change on the Prairies. Meteorologist Christy Climenhaga will bring her expert voice into the conversation to help explain weather phenomena and climate change and how it affects everyday life.


It is the world’s largest forest with the least disturbance. A patch of trees spreading across the globe, accounting for a third of the Earth’s forested area.

We are talking about the boreal forest. The planet’s coldest forest – a huge repository of carbon accumulated over thousands of years and a thriving ecosystem for plants and animals.

In Canada, more than 300 million acres of boreal forest stretch from Yukon all the way through the northern half of the provinces, eastwards to Newfoundland. The boreal forest is home to half of the country’s bird species and 3.7 million people.

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As our climate changes, this vast expanse of cold forest is getting warmer. According to Environment and Climate Change Canada, mean temperatures in the prairies have been 1.9°C warmer since the mid-20th century.

Winters are generally shorter and milder. Summers get hotter with not enough moisture to offset the heat. While some of these changes may seem small, they have major implications for our local ecosystems, including the boreal forest.

So what will happen to this beacon of Canadian wilderness if our climate continues to change? Will it survive?

Scientists say we are already seeing a shift.

Climate change could cause Canada’s boreal forest to creep north. This is why

As summer weather warms, pests, risk of wildfires and fluctuating precipitation can cause parts of our southernmost boreal forest to die, as the northern part expands into the warming Arctic. Meteorologist Christy Climenhaga explains.

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Boreal is constantly changing

Change is nothing new to the boreal forest. It is under constant pressure from natural disturbances – things like fire and insects – that can help the forest renew itself and become more resilient.

But what happens when these disruptions become more frequent, when they start to become the new normal?

That is the lens we look through as we continue to see our climate change at a rapid pace.

“If we think of drought, fire, insects and disease, this large area is constantly dealing with all these threats. But with climate change, at least some of these threats will become more severe,” said Janice Cooke, a professor of biological sciences at the University of California. Alberta.

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Water stress and trees

When the mercury rises, evaporation takes place more easily and plants lose water at a rapid rate through transpiration. If it is not replaced, we start to have moisture deficiencies. And the longer those shortages last, the more stress they put on our plants.

“When trees are faced with a lack of water, it’s pretty serious. They close their pores on their leaves and they try to survive,” Cooke says.

By trying to conserve water, they don’t get the sugars or resources they need to grow.

Cooke says that if growth is stunted, the trees also lose a bit of their ability to remove carbon dioxide from the atmosphere, which begins to spiral into a vicious circle.

“We know that those high temperatures cause more drought. It’s a dangerous feedback loop.”

Water stress can affect growth along the southern edge of the boreal forest through climate change. (David Bajer/TBEN)

The boreal and the prairies

While you might imagine a skyline of endless grassland, the boreal forest covers more than half of our prairie provinces.

In Alberta and Saskatchewan, the northern half of both provinces is rooted in the boreal region, and in Manitoba it extends even further south, occupying three-quarters of the province.

But the health of that forest is already changing in the Prairies.

Ted Hogg, researcher emeritus in the Canadian Forest Service’s Climate Change Program, studies the deteriorating health of forests.

“The major impacts we’re seeing are in northern Alberta, where we’ve had severe droughts on a regular basis since 2002,” he says.

Hogg says the 2002 drought meant a major loss of trees in the Aspen Park and the southern boreal region between Edmonton and Saskatoon. But recent droughts are extending that tension northwards.

“What we’ve seen recently is that some other parts around Peace River, in northwestern Alberta, and even as far as the Northwest Territories, have seen similar things…so aspen mortality has gone beyond us.” ever expected.”

According to Diana Stralberg, a research scientist at the Northern Forestry Center with Natural Resources Canada, these stressors could lead to a shift in the forest towards more of a prairie grassland system.

“If you’ve had a fire followed by drought, where the seeds or seedlings don’t survive and then they are hit again by a fire, you could be at risk that could lead to a lack of forest regeneration.”

Stralberg says if we see dieback in the parks of Alberta and the southern boreal regions, we may see the forest shift north.

Smoke and flames from the wildfires erupt behind a car on the highway near Fort McMurray, Alberta, Canada, May 7, 2016. Climate change could potentially double the amount of northern boreal forest burned by 2100, according to Natural Resources Canada compared to past decades . (Mark Blinch/Reuters)

A march to the north

That shift of an ecosystem is no small feat, but it’s something more scientists are seeing.

Logan Berner, an assistant research professor at Northern Arizona University, has studied the state of the global boreal region.

“There is mounting evidence that as the climate continues to warm, the boreal region may shift northward,” he says.

This shift would mean an expansion of boreal trees and shrubs into Arctic and alpine tundra, Berner said, and possibly a contraction of forest along the southern margins.

In his research, Berner studies the browning and greening of trees – basically where growth increases and where it decreases.

Berner looked at a number of locations in the boreal forest between 1985 and 2019 to see how growth trends were changing. He says they saw more greenery at the northern edge of the forest.

Berner’s study showed more forest growth in the Arctic and more dieback in the prairie boreal forest. (Logan Berner, Scott Goetz/Northern Arizona University)

“We think this is mainly due to higher temperatures, which can allow trees and shrubs to grow taller and increase their footprint and extend along the forest.”

Berner says that in contrast to the northern greening, there were significant decreases in vegetation gradients in parts of the southern boreal forest in North America and Eurasia.

“These are kind of early indications that a … shift could be happening.”

But even if trees begin to populate further north, it can’t make up for lost habitat to the south, Stralberg says.

“You can lose forest much faster than it can grow and provide habitat for wildlife. So if you lose an older forest here in the south, you don’t really have the opportunity to make up for that very quickly.”

Stralberg says this means many species that rely on older mature forests, especially coniferous forests, could struggle.

“Because we have more open forests and more grassland, you can see different species coming in. But the fact is that these things happen so fast that it’s very easy to be at a loss, especially when you come together with all the other human activities.”

Stress from pests

Insects are another piece of the boreal climate puzzle as we continue to see warming.

As trees struggle with the lack of water, this could mean openings for insects, says Jennifer Klutsch, a research scientist at Natural Resources Canada and a forest entomologist.

“Drought stress can lead to those trees not being properly defended against not only native insects and pathogens, but also extensions of their range, such as the pine beetle,” she says. “That can lead to greater outbreaks, frequency and severity.”

The verdant forests in and around Jasper National Park are increasingly marred by red, rust-colored trees, a sign that the mountain pine beetle has devastated the areas. (Alex Zabjek/TBEN)

It also comes down to timing, Klutsch says. With their shorter life cycles, insects can react more quickly to changes in temperature and humidity than trees.

“They can build populations and trees can’t really adapt to this new disturbance regime that comes their way.”

And with warmer winters, insect populations could grow.

“If we don’t get the cold winters we expect in the boreal, it could lead to bark beetle populations being sustained because of that lack of winter mortality.”

It is too late?

Well, here’s the glimmer of hope.

While we are clearly seeing changes in our boreal region, changes can still be made.

“I think it’s inevitable to some extent that we’re on this trajectory of warming that we need to respond to and adapt to,” Stralberg says. “I think we can reduce the damage to some extent.”

She says it has the potential to look at the landscape, find the areas that are more resilient, and protect or preserve them.

“Areas with larger peat complexes and more interfaces between the upland forests and the peatlands, I think you have more potential there to really keep that water in the landscape,” she says.

According to Stralberg, small-scale changes in topography in specific locations where you can have some shade and protection from direct sunlight, and the ability to conserve water also have potential.

Cooke agrees that there is still time to take action to protect this vital ecosystem.

“Is it ever too late to do something better? I would say no. We can always try to do better and hope it works, but we can never turn back the clock.”


Our planet is changing. So is our journalism. This story is part of a TBEN News initiative titled “Our Changing Planet” to show and explain the effects of climate change. Stay up to date with the latest news on our Climate and Environment page.

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