It is the largest forest in the world with the least disturbance. A section of trees that sweeps across the globe, accounting for a third of the Earth’s forested area. We are talking about the boreal forest. The coldest forest on the planet – a huge store 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 all the way through the northern half of the provinces, east to Newfoundland. The boreal forest is home to half of the country’s bird species and 3.7 million people. As our climate changes, this vast expanse of cold forest is warming. Average temperatures on the prairies are 1.9 degrees warmer than the mid-20th century, according to Environment and Climate Change Canada.
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Winters are getting shorter and milder. Summers are getting hotter with insufficient humidity to offset the heat. While some of these changes may seem small, they have big impacts on our local ecosystems, including the boreal forest. So what will happen to this beacon of 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. Here’s why
As summer weather warms, pests, fire risk and changing precipitation could cause parts of our southernmost boreal forests to die – while northern areas expand into the warming Arctic. Meteorologist Christy Climenhaga explains.
The Boreal is constantly changing
Change is nothing new to the boreal forest. It is under constant pressure from natural disturbances – such as fire and insects – that can help the forest regenerate and become more resilient. But what happens when these disorders occur more frequently, when they start to become the new normal? This is the lens 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 area faces all these threats all the time. But under climate change, at least some of these threats will become more severe,” says Janice Cooke. professor of Biological Sciences at the University of Alberta.
Water stress and trees
When the mercury rises, evaporation occurs more easily and plants lose water at a high rate through transpiration. When it is not replaced, we begin to enter moisture deficits. And the longer these deficits last, the more stress they put on our plants. “When trees experience a lack of water, it’s very severe. They close the pores in their leaves and try to cope,” says Cooke. By trying to conserve water, they don’t gain the sugars or resources they need to grow. Cooke says that as growth slows, trees also lose some of their ability to remove carbon dioxide from the atmosphere, which starts to turn into a vicious cycle. “We know that these high temperatures cause more drought. It’s a dangerous feedback loop.” Water stress could affect growth along the southern edge of the boreal forest with climate change. (David Bajer/CBC)
The north and the meadows
Although you can imagine a horizon of endless grasslands, the boreal forest covers more than half of our grassland provinces. In Alberta and Saskatchewan, the northern half of both provinces has its roots in the north, and in Manitoba it extends even further south, covering three-quarters of the province. But the health of this forest is already changing in the Meadows. Ted Hogg, a researcher emeritus 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 meant a lot of tree loss in Aspen Park and the south-north section between Edmonton and Saskatoon. But recent droughts are extending that stress northward. “What we’ve seen more recently is some other places in places near the Peace River, in northwestern Alberta, and even as far as the Northwest Territories, where we’ve seen similar things happening … so the die-offs of aspins have gone further than we ever expected.” . According to Diana Stralberg, a researcher at the Northern Forestry Center with Natural Resources Canada, these stressors could lead to a shift of the forest to a prairie grassland system. “When you have a fire followed by a drought, where the seeds or seedlings don’t survive and then get hit by fire again, you can have a risk that can lead to a lack of forest regeneration.” Stralberg says that as we see it die off in the Alberta park and the southern northern regions, we may see the forest shift northward. Smoke and flames from wildfires billow from behind a car on the 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 in 2100 compared to the last few decades. (Mark Blinch/Reuters)
A march to the north
This shift of an ecosystem is no small feat, but it is something more scientists are seeing. Logan Berner, assistant research professor at Northern Arizona University, studies the state of the global north. “There is emerging evidence that as the climate continues to warm, the northern part may shift north,” he says. That shift would mean an expansion of northern trees and shrubs in the arctic and alpine tundra and possibly a shrinking of the forest along the southern fringes, according to Berner. In his research, Berner studies the browning and greening of trees—basically, where growth increases and where it decreases. Berner looked at a series of sites within the boreal forest between 1985 and 2019 to see how development trends had changed. He says they saw increased greening on the northern edge of the forest. Berner’s study showed greater forest growth in the Arctic, and greater decline in the northern prairie forest. (Logan Berner, Scott Goetz/Northern Arizona University) “We think this is mainly due to warmer temperatures, which makes it possible for trees and shrubs to grow and expand their footprint and spread across the forest.” Berner says that in contrast to the northern greening, there have been significant declines 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 as trees begin to colonize further north, Stralberg said, it may not replace the habitat lost in the south. “You can lose forest much faster than it can grow and create habitat for wildlife. So if you lose an older forest here in the south, you don’t really have a chance to replace it very soon. ” Stralberg says that means many species that depend on older mature forests, especially coniferous forests, could struggle. “As we get more open woodland and more grassland conditions, then you could see different species coming through. But the fact is that these things happen so quickly that it’s very easy to have a loss, especially when you combine all the other human activities.”
Pest stress
The bugs make up another piece of the northern climate puzzle as we continue to see warming. As trees struggle with a lack of water, that could mean openings for insects, says Jennifer Klutsch, Natural Resources Canada researcher and forest entomologist. “Drought stress can result in these trees not being very well protected not only from native insects and pathogens, but also from range expansions such as the mountain pine beetle,” he says. “This can lead to greater outbreaks, frequency and severity.” The lush forests in and around Jasper National Park are increasingly marred by red, rusted trees, a sign that the mountain beetle has ravaged the areas. (Alex Zabjek/CBC) It’s also about timing, says Klutsch. Insects, with their shorter life cycles, can respond more quickly to changes in temperature and humidity 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 could increase. “If we don’t have the cold winters we expect in the north, then that can lead to the maintenance of beetle populations due to the lack of winter mortality events.”
It’s too late;
Well, here is the ray of hope. While we are clearly seeing changes in our northern region, changes can still be made. “I think to some extent there’s an inevitability that we’re on this warming trajectory that we have to respond to and adapt to,” Stralberg says. “I think to an extent we can mitigate the damage.” He says there is an opportunity to look at the landscape, find the areas that are most resilient and try to protect or preserve them. “Areas that have larger peatland complexes and more interfaces between upland forest and peatland, I think that’s where you have more potential to really keep that water in the landscape,” he says. According to Stralberg, small changes in the topography in specific locations where you can get some shade and protection from direct sun, as well as the ability to conserve water, also have potential. Cooke agrees there is still time to act to protect this vital ecosystem. “Is it ever too late to do better? I’d say no. We can always try to do better and…
