Ecologist studies underground networks to heal B.C. forest

Western hemlock seedlings in UBC’s Malcolm Knapp Research Forest regenerate with the help of their elders.

The mother tree ascends 100 metres into the forest canopy.  In more than 100 years of life, she has survived pests, diseases, droughts and fires. Dozens of her kin rely on her and she provides for them. She uses underground networks to ferry nutrients, water and ancient knowledge to her young.

But she’s up against a lot.

Since the early 1990s, mountain pine beetle infestations have wiped out nearly half of all harvestable lodgepole pine trees in the province, more than 18 million hectares. A spruce-beetle infestation has hit B.C.’s northern forests, the largest outbreak since the 1980s. In the past year, more than 280,000 hectares of forest burned in wildfires.

Climate change fuels and compounds the devastation.

Add to this a hungry logging industry and it’s no surprise that, over the last 10 years, B.C.’s forests went from being a net carbon sink to a net carbon source. They now emit more carbon dioxide and other greenhouse gases than they remove from the air.

Suzanne Simard believes better forest management is possible and she just won a $929,000 grant from the Natural Sciences and Engineering Research Council of Canada to figure out how.

Simard, a forest ecologist and professor at the University of British Columbia, studies how trees organize themselves in families and use subterranean structures called mycorrhizal networks to communicate. She says taking mycorrhizal networks into account will help mitigate the many disturbances that threaten B.C.’s forests.

“All the trees in the forest are connected below ground. They behave like communities,” Simard says. “They’re a forest, not just a bunch of trees.”

Simard wants to find better ways to harvest timber. The B.C. Ministry of Forests and one of B.C.’s largest reforestation companies, the Brinkman Group, are on board.

Forests take care of themselves

Mycorrhizal networks form when an underground fungus makes contact with the roots of at least two trees. This creates lines of communication between all the entities connected to the network. Trees can use the network to share resources and even warn each other of danger.

Fungi connect with trees to create a plant-to-plant hotline called a mycorrhizal network.

A UBC researcher shows how fungi connect with trees to create a plant-to-plant hotline called a mycorrhizal network.

Scientists have known that fungi form mutually beneficial associations with plants since the 19th century. It wasn’t until the late 1960s that evidence of plant-to-plant chatter through these networks began to emerge. Dozens of researchers are studying this phenomenon.

Mother trees are the oldest and most connected. They can take the extra sugars they’ve photosynthesized and feed them into the mycorrhizal network. Younger seedlings, not yet large enough to reach into the canopy and soak up sunlight, can suck those sugars out and greatly improve their chances of survival.

Simard says mother trees carry legacies. Their DNA contains knowledge accumulated over centuries. The information is passed down to young trees, carrying ancient wisdom from generation to generation. The forest’s natural stewardship creates home-grown resilience — an adaptive edge for environmental disturbances like climate change.

“We could leave that structure in place to help the next generation capitalize on that DNA bank and the evolution that’s happened [to create] a resilient forest,” Simard says. “But we don’t. We clearcut and we take out all the trees.”

Simard is trying to figure out the best way to harvest timber while also keeping the forest’s legacies intact.

Over the next few years, she’ll be running experiments in BC’s interior forests to simulate different harvesting methods to compare the effects on forest regeneration.

She’s currently setting up experimental sites from southern B.C. up to near Prince George.

In the summer, some of those sites will be entirely clear-cut. Others will only be harvested moderately, so that mother trees remain to support new growth. Both will be replanted with seedlings. Their growth and health will then be monitored closely over the years. Based on her previous research, Simard expects that the seedlings planted at sites where mother trees still remain will grow faster and healthier.

Seedlings at the clear-cut site are expected to have stunted growth.

“If we take out all the beautiful old trees, that means that that connection, the physical and communication connection, is being compromised,” Simard says. “The work that we’re doing is trying to ask ‘Is there another way we can manage these forests?'”

Growing pains

B.C.’s forest industry pegged total revenue at $15.7 billion in 2013. Forest products are BC’s largest export, and wood-product manufacturing is B.C.’s largest industry.

This has led to harvesting methods that focus on getting the biggest trees to market fastest in order to maximize production. Though economically efficient, it translates to simplified practices like clearcutting and replanting of quick-growing, commercially valuable species like the lodgepole pine, which makes up more than half of replanted species.

This has been shown to be problematic for forest resilience. Earlier research by Simard looked at lodgepole pine plantations around Williams Lake 20 years into their regeneration. She found about half no longer met government-set reforestation targets. Current regeneration methods are failing.

Seedlings in an old-growth forest gain resources through the mycorrhizal network.

Seedlings in UBC’s research forest grow next to older trees.

Around 200 million trees are planted each year and allotted time to reach “free growing” status, anywhere from seven to 20 years, at which point industry’s obligations are complete. B.C. is in charge of these standards, as 94 per cent of forest lands are owned by the Crown.

The destabilization of B.C.’s forests is not just a situational crisis, said Simard. It’s a problem with management.

“We’re fooling ourselves to think that what we’re doing is actually a sustainable practice,” says Simard.

There has been some improvement.

The Ministry of Forests recognizes the importance of variable retention, or “clearcutting with reserves,” where some trees are saved within or outside the cut boundary. According to the ministry, in 2014, clearcutting with reserves accounted for 87 percent of the area harvested on public land.

But according to Simard, it’s not enough.

“By and large, what it has translated into is clearcutting,” she says. It often means leaving trees around the perimeter of the site, for what the ministry calls “visual landscapes.”

A  2012 auditor general report on ministry management of timber identified many problems, including a lack of monitoring and information.

“We’re not protecting the habitat of those trees and protecting the most diverse and valuable part of the ecosystem,” says Simard.

Gabriel Orrego, one of Simard's graduate students, stands amongst old growth trees in the UBC Malcolm Knapp Research Forest.

Gabriel Orrego, one of Simard’s graduate students, stands amongst old growth trees in the UBC Malcolm Knapp Research Forest.

Everyone has an interest in improving resiliency, as Simard’s research partnership with government, private industry and science demonstrates.

“That’s what this grant proposal is about, to test some of these things in our warming climate and come up with some alternatives and demonstrate to the public that there are different ways to do these things and they are healthier for us,” Simard says.

For Simard, this moment presents a huge opportunity.

“We can make some fundamental changes that would make such a big difference,” she says.