Ted Hogg’s research usually takes him much deeper in Canada’s boreal forest — but on a chilly day strolling through Edmonton’s river valley, it doesn’t take long before he sees examples of the damage he’s looking for.
Pointing to several of the snow bearing trees, he indicates the deaths he’s already witnessing from climate change.
“There’s a lot of trees dying. Different types of trees. There’s dead poplar, you can see the dead tops up there. Behind us is dead birch. And then there’s spruce ahead of us that’ve died a few years ago,” he said.
Hogg is a research scientist with the Canadian Forest Service, a subsector of Natural Resources Canada.
“This seems to be a pattern throughout our urban forest here in Edmonton, but it’s also something that’s been happening over a larger area of Western Canada.”
Edmonton sits at the southern edge of the boreal forest 一 the largest forest in Canada. The behemoth covers more than half of the country’s land mass, a swath that stretches from Yukon to Newfoundland and Labrador.
Water, or lack thereof, is the biggest factor in the forest’s slow death, Hogg said. Repeated droughts have pretty well made dry conditions the new norm since the turn of the millenia.
“The rate of tree death will increase for up to 10 years after even one severe drought,” Hogg said. “With these repeated droughts, that’s where we’re really seeing an escalation of tree mortality.”
Trees are adaptable, but only within certain limits, and right now they’re dying at a consistent rate two to nearly four-times what was seen before 2000.
About four to five per cent of the Aspen Hogg studies as an example species is dying each year.
In the most extreme cases, tree stands that used to house birds and forest animals are flat out disappearing with mortality rates nearing 100 per cent. Where trees once stood, there is now Prairie grasslands.
“We have some examples of that, but it’s generally over smaller areas. And it tends to be in the more drought-affected areas,” Hogg said. Overall, it is mostly a slow degradation and deforestation isn’t widespread, yet. “Although that’s a concern for the longer term.”
With dry conditions and standing dead trees, there are two imminent threats that arise. The first are pests and disease ravaging the already-stressed trees, which are now more susceptible to attack. The mountain pine beetle has been able to spread its range from B.C. to Alberta across the Rockies because warmer winters allow it to thrive.
The second threat announces itself each summer with socked-in red skies in Western Canada as the forest transforms into a tinderbox, resulting in record wildfires.
A tree — or in this case a massive forest — offers an opportunity for a natural process to strain carbon from the atmosphere using photosynthesis. The trouble is that while a tree can store carbon in its biomass, it can also spit it back out. Forest fires offer a very quick release of the stored carbon, sending it billowing into the air in choking grey plumes.
But as the trees die off more slowly over the course of years, carbon is still being released.
“It is a huge effect on the carbon cycle,” Hogg said.
“Huge effect” may well be an understatement.
For years, some Canadians have hid behind the myth that the country isn’t a net emitter of greenhouse gas emissions because of the presence of such vast forests working as our personal atmosphere vacuums. And up until the last two decades, it is true that those forests had the power to sequester in excess of a hundred megatonnes of carbon dioxide equivalent each year.
But that is no longer the case.
Natural Resources Canada tracks the estimations of carbon released and captured by the managed forest each year — with managed forests accounting for about 65 per cent of the country’s trees.
The results: Canada’s forests have not captured more carbon than they’ve emitted since 2001.
This isn’t a small swing in the wrong direction. In 2015, Canada’s forests emitted the equivalent of 231 megatonnes of carbon dioxide. To put that in perspective, all of the people in Calgary emit 18.3 megatonnes.
The biggest cause of this shift is what Natural Resources Canada terms “natural disturbances” — fires, pests, disease and increased mortality.
“So we try to figure out ways that we can store the carbon longer,” said Carolyn Smyth, a research scientist with the Pacific Forestry Centre run out of Natural Resources Canada.
Smyth and her colleagues are looking at ways to mitigate emissions from managed forests.
“In some cases that might be putting the carbon into wood products that we use to build houses, that we use for paper, and for many other uses.”
They’re also considering using altered seeds when replanting, ones meant for warmer drier climates ─ perhaps allowing for new trees to adapt to the new climate. Using dead trees as biofuels is also in the works.
“We’ve looked at some conservation strategies as well,” Smyth said. “So if we set aside regions and we say, ‘You can’t harvest these.’ It can be good, it keeps the trees sequestering carbon for longer. But there is a risk of reversal. There’s a risk of having a wildfire, or pests, or drought kill the trees and then it no longer stores a lot of the carbon, it releases it back into the atmosphere. So we want to be very careful in conservation strategy.”
Mike Flannigan looks at Canada’s estimated emissions and says they are vast underestimations of what is really being emitted.
As a professor of wildland fire at the University of Alberta he’s looked at areas outside of Natural Resources Canada’s managed forests and says the same patterns can be seen there but to even greater extremes.
Peat bogs are what really concern him. These wetlands can have meters of moss and peat built up over long periods of time and they contain far more carbon than the regular upland forests do. And nearly all of these bogs are found in unmanaged forests, he says, since they don’t have much use in the forestry industry.
So what’s the big deal about peat?
“It burns really well,” Flannigan says to start. He uses Indonesia as an example.
In 1997, they had a particularly bad fire year where huge areas of peat were burned. When researchers tried to estimate how much carbon was emitted in those fires, they couldn’t pin down an exact figure but estimated between 0.81 and 2.57 gigatonnes of carbon. That would have been the same as between 13 and 40 per cent of global annual average emissions from fossil fuels at that time.
“The boreal [forest] has 30 times more peat than Indonesia. Indonesia is a drop in the peat bucket,” Flannigan explained.
So needless to say, the numbers published by Natural Resources Canada are bad, but the emissions that aren’t being accounted for would worsen the numbers substantially.
Researchers are looking across national borders to learn from one another as they face similar threats. “It’s the same everywhere,” Michel Vennetier said, from subtropical African climates to the boreal forest.
Vennetier is one of the world’s leading experts in forestry engineering based in southern France at the National Research Institute of Science and Technology for Environment and Agriculture.
“Each time I go into the forest with representatives of the towns, the services of state, and so on, I tell them, ‘Just look at the forest and tell me, do you think something is wrong?’ And recently I was in front of a beautiful landscape forest and people were saying, ‘Well this is normal.’ And I tell them, ‘Just look. One fourth of the trees are dead,’” Vennetier said. “And they just didn’t notice.”
Fires have draw attention to France’s deteriorating forest health. Fires that used to be regarded as natural opportunities for regeneration, have become devastating in a new way.
Since different ecosystems have varied thresholds for how often they can stand to be burned, the forests near the Mediterranean coast of France, Vennetier says, have thresholds between 25 and 30 years.
But fires are no longer that patient.
“When you are over that threshold, regeneration is easy. When you go under this threshold, it’s not just a progressive trend, it’s just a very rapid collapse of the ecosystem,” Vennetier explained.
“So the fact that a [small] percentage of the landscape is burned more than the threshold is not bad. But the problem is when the majority of the landscape is. And in the last years we’ve observed an increase in the area that has burned more than once in 25 years … And then we observe that the ecosystem is collapsing. The trees are disappearing.”
What France is facing is likely foreshadowing for Canada, Flannigan says.
“[The boreal forest is] used to fire and has survived and thrived in fire. But if fire becomes too frequent the forest will disappear,” Flannigan said. “I have some colleagues who think it’s going to happen this century. I don’t think it’s going to happen as quickly as that. I think there’s still a fair bit of resilience.”
The Canadian Forestry Service anticipates at least a doubling in the area of forest burned annually by 2100.
What all of these researchers are certain of is that the positive feedback loop is in progress: the hotter it gets, the more fire there is, the more fire there is, the more emissions there are, so the world warms even further.
Hogg says the most direct way of slowing these changes in the boreal is to drastically reduce global GHG emissions, but that is above his paygrade.
“It is difficult to see these large-scale changes especially when we think about what it could mean down the road, you know, 10 or 20 years from now. I have an ammateur interest, for example, in bird watching, bird photography. We know that’s important habitat. Those trees are what allow all these species to be here. So it’s a big concern.”
Flannigan says there are ways in which forest management can be used to mitigate fire risks but they are financially unviable in Canada due to the magnitude of the forests here. He too concludes lowering emissions is really the only way to change course.
“Sometimes it takes a few bloody noses for human behaviour to change,” Flannigan said. “People sometimes need a couple lessons before they change behaviour. I actually think we’re going to need another bloody nose or two.”
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