CBC Alberta and Saskatchewan have teamed up for a new pilot series on prairie weather and climate change. Meteorologist Kristi Klimenhaga will bring her expert voice to the conversation to help explain weather phenomena and climate change and how they affect everyday life.
It is the world’s largest forest with the least disturbance. A strip of trees stretching across the globe, representing one-third of the Earth’s forested area.
We are talking about the boreal forest. The coldest forest on the planet – a huge storehouse of carbon accumulated over thousands of years and a thriving ecosystem for plants and animals.
In Canada, over 300 million hectares of boreal forest stretch from the Yukon across the northern half of the provinces, eastward to Newfoundland. The boreal forest is home to half the country’s bird species and 3.7 million people.
As our climate changes, this vast expanse of cold forest is getting warmer. Average temperatures on the Prairies are 1.9C higher than the mid-20th century, according to Environment and Climate Change Canada.
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Winters are generally becoming shorter and milder. Summer is getting hotter with insufficient moisture to compensate for the heat. While some of these changes may seem small, they have a big impact on our local ecosystems, including the boreal forest.
So what will happen to this beacon of the Canadian wilderness as our climate continues to change? Will he survive?
Scientists say we’re already seeing a change.
Climate change could send Canada’s boreal forest creeping north. that’s why
As summers warm, pests, the risk of wildfires and changing rainfall could see parts of our southernmost boreal forests die off – while northern parts expand into the warming Arctic. Meteorologist Christy Klimenhaga explains.
The 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 regenerate and become more resilient.
But what happens when these disruptions happen more often, when they start to become the new normal?
This is the prism through which we look as we continue to see our climate change at a rapid pace.
“If you think about drought, fire, insects and disease, this large tract is fighting all these threats all the time. But with climate change, at least some of these threats will become more severe,” said Janice Cook, a professor of biological sciences at the University of Alberta.
Water stress and trees
As the mercury rises, evaporation becomes easier and plants lose water at a high rate through transpiration. When it is not replaced, we begin to become deficient in moisture. And the longer these deficiencies last, the more stress they put on our plants.
“When trees face a lack of water, it’s quite serious. They close their pores on their leaves and try to hold on,” says Cook.
By trying to conserve water, they are not gaining the sugars or resources they need to grow.
Cook says that as growth is slowed, the trees also lose some of their ability to remove carbon dioxide from the atmosphere, which starts to become a vicious cycle.
“We know that these increased temperatures create more drought. This is a dangerous feedback loop.”
Water stress may affect growth along the southern edge of the boreal forest with climate change. (David Bayer/CBC)
The boreal and the prairies
Although you might imagine a silhouette of endless grasslands, 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, and in Manitoba it extends further south, covering three-quarters of the province.
But the health of that forest is already changing on the prairies.
Ted Hogg, an emeritus scientist in the Canadian Forest Service’s climate change program, studies declining forest health.
“The big impacts we’re seeing are in northern Alberta, where we’ve had frequent severe droughts since 2002,” he says.
Hogg says the 2002 drought led to a large loss of trees in the aspen and southern boreal park between Edmonton and Saskatoon. But recent droughts are extending that stress north.
“What we’ve seen recently is some other parts of places near the Peace River, northwestern Alberta and even up in the Northwest Territories, we’ve seen similar things happening … so aspen mortality has gone further than we ever expected.” “
According to Diana Stralberg, a researcher at Natural Resources Canada’s Center for Northern Forestry, these stressors can cause the forest to shift to a prairie grassland system.
“When you have a fire followed by a drought, where the seeds or seedlings don’t survive and then are hit by fire again, you can have a risk that can lead to a lack of forest regeneration.”
Stralberg says as we see die-offs in Alberta’s parks and the southern boreal regions, we may see forests shift north.
Smoke and flames from wildfires billow from behind a car on a highway near Fort McMurray, Alberta, Canada, May 7, 2016. According to Natural Resources Canada, climate change could potentially double the amount of northern boreal forest burned by 2100 compared to the last decades. (Mark Blinch/Reuters)
March to the north
This change of an ecosystem is no small feat, but it is something that more scientists are seeing.
Logan Berner, an assistant research professor at Northern Arizona University, studies the state of the global boreal region.
“There is new evidence that as the climate continues to warm, the boreal may shift north,” he says.
This change would mean an expansion of boreal trees and shrubs in the arctic and alpine tundra and a potential shrinking of the forest along the southern fringes, according to Berner.
In his research, Berner studied the browning and greening of trees—basically, where growth increases and where it decreases.
Berner looked at several locations in the boreal forest between 1985 and 2019 to see how growth trends had changed. He says they have seen increased greening at the northern end of the forest.
Berner’s study showed more forest growth in the Arctic and more dieback in the prairie boreal forests. (Logan Berner, Scott Getz/Northern Arizona University)
“We think this is mostly due to warmer temperatures, which makes it possible for trees and shrubs to grow larger and expand their footprint and spread out across the forest.”
Berner says that in contrast to northern greening, there are significant declines in vegetation gradients in parts of the southern boreal forest in North America and Eurasia.
“These are kind of early indications that there might be … change.”
But even as trees begin to populate further north, Stralberg says, it may not make up for the habitat lost to the south.
“You can lose a 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 an opportunity to make up for that very soon.”
Stralberg says that means many species that depend on older, mature forests, especially conifers, may struggle.
“Because we have more open woodland and more grassland, then you can see different species coming in. But the fact is, these things happen so quickly that it’s really easy to have a loss, especially when combined with all the other human activities.”
Pest stress
Insects make up another piece of the boreal climate puzzle as we continue to see warming.
As trees struggle with a lack of water, that can mean openings for insects, says Jennifer Kluch, a Natural Resources Canada researcher and forest entomologist.
“Drought stress can mean that these trees are not very well protected against not only native insects and pathogens, but also range expansion, like the mountain pine beetle,” she says. “This could lead to larger outbreaks, frequency and severity.”
The green forests in and around Jasper National Park are increasingly marred by rust-colored redwoods, a sign that the mountain pine beetle has ravaged the areas. (Alex Zabjek/CBC)
It also comes down to timing, Kluch says. Insects, with their shorter life cycles, can respond more quickly to changes in temperature and moisture than trees.
“They can build up populations and the trees aren’t really able to adapt to this new disturbance regime that’s coming their way.”
And with warmer winters, bug populations can grow.
“If we don’t get the cold winters that we kind of expect in the boreal, then that could lead to sustaining bark beetle populations because of that lack of winter mortality.”
Is it too late?
Well, here is a glimmer of hope.
Although we are clearly seeing changes in our boreal region, changes can still be made.
“I think to some degree there’s some inevitability that we’re on this warming trajectory that we have to respond to and adapt to,” Stralberg says. “I think we can mitigate the damage to some extent.
She says there is potential in looking at the landscape, finding areas that are more resilient and trying to protect or preserve them.
“Areas that have larger peatland complexes and more interfaces between upland forests and peatlands, I think that’s where you have more potential to really hold that water on the landscape,” she says.
According to Stralberg, small-scale changes in the topography in certain places where you can have some shading and protection from direct sun, as well as the ability to hold water, also have potential.
Cook agrees that there is still time to act to protect this vital ecosystem.
“Is it ever too late to do better? I would say no. We can always try to do better and…
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