How Mushrooms Could Help Replenish Forests After Clearcut Logging

This is Part 2 in a series about experimental forestry on Cortes Island. Click here for Part 1.

The small community that lives on Cortes Island, a remote and richly forested spot off the British Columbia coast, is known for fiercely protecting its trees. It’s been successful in the past at fending off big timber companies, yet Cortes still hasn’t been entirely spared the chainsaw. Just like the rest of the province, clearcuts are scattered about the island in various states of partial regrowth. Only isolated groves of old growth trees remain.

Cortes has a way of attracting some of the top eco-intellectuals in the world. Some have set about to heal these wounds by purchasing clear-cut lands and attempting to restore them.

One of the biggest names on the island is mycologist Paul Stamets, who is best known for deploying fungi to clean up humanity’s worst messes. He has been coming to Cortes from his home in Washington State since 1988 to teach workshops on mushroom cultivation and foraging. In the early 2000s, he bought 160 acres of land on Cortes—90 acres of intact forest and 70 acres that had been clear-cut.

Paul Stamets on Cortes Island. Image: Daniel J. Pierce

Stamets and a small team intend to use fungi nurse this clear-cut tract of land back to health, and set it on a path to eventually becoming an old-growth forest once again.

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After the glaciers receded from the Pacific Northwest some 10,000 years ago, glacial moraine was left behind—basically a big pile of rocks and rubble, with scattered patches of soil. As time went on and plants grew and decayed in these isolated soil deposits, the layer of decaying organic matter known as humus grew thicker and healthy soils slowly spread across the landscape. At the vanguard of these expanding islands of soil were fungi.

Given the massive size of some of the trees on the West coast, you might think there’s endless soil to root them into the ground. But in reality, the layer of topsoil that holds them up is absurdly thin, only about three feet deep or so. That’s where the fungi come in.

A Douglas fir, part of the myco-forestry project. Image: Daniel J. Pierce

While we’re all familiar with the mushrooms that spring out of the ground, the real heroes are the mycelium—an underground network of tiny white threads that look much like spiderwebs branching out through the soil, unlocking nutrients and defeating pathogens. Stamets has famously compared this to the forest’s natural internet, connecting all the trees and plants, transmitting nutrients, sugars and even messages throughout the forest floor.

Mycelium, of course, can’t spare a forest from being clear-cut, and in B.C., this type of logging has a long history. “When the first European settlers came to Western North America, and they saw these beautiful old-growth trees, they cut them down, removed the trees and then they burned [the waste],” Stamets told me. According to him, that makes “two withdrawals from the carbon bank.”

Mushroom growing at the myco-forestry project. Image: Daniel J. Pierce

This practice of logging and burning has gone on for as many as three consecutive harvest rotations in some places. To deal with the staggering amount of wood-waste that is left on the ground after clear-cutting, slash burning is standard practice in B.C.

This is a massive source of carbon. Rather than that carbon going back into the soil, where it can become plant food, it’s being sent into the atmosphere, contributing to global warming.

“By the fourth and fifth rotations, the humus layer declines, trees topple over earlier and earlier, because the root wads are not thick enough to hold the trees,” Stamets said.

Waste wood piled up to be burned. Klanawa Valley, Vancouver Island, BC. Image: TJ Watt

This was the main driver behind his myco-forestry project. He wanted to get away from burning woody debris, and accelerate the process of turning that wood detritus back into healthy soil.

Read More: How Mushrooms Could Hold the Key to Our Long-Term Survival as a Species

To this end, Stamets’ property has been divided into four sections. In section one, he and his team placed a collar of wood chips around the bases of the trees they planted, which were mostly Douglas fir and Western red cedar. In section two, they tried dipping their roots into a slurry of fungal spores. In section three, they used a combination of wood-chips and fungi. And the final section was a control group, where they planted trees in the clear-cut soil and simply let them grow on their own.

“33,000 trees were planted and tagged,” Stamets said. “We [selected] 1,100 of them that we're tracking, and we’ve been laboriously measuring them. This is a labor of love,” he continued. He and his wife are footing the bill for the project, and he praises the “dedication of great employees” and local volunteers from Cortes Island for making it possible.

An aerial view of the myco-forestry project. Image: Daniel J. Pierce

They have started to see some statistically significant results. The trees that got the wood-chips and had their roots dipped in fungi experienced lower mortality rates, and are now 10 percent larger on average than the trees that were not inoculated with the fungi, Stamets told me. These trees are clearly getting help from their fungal partners.

“The bottom line is to show that you can create more timber in a shorter period of time without burning, [and] without that CO2 burst,” he said.

Oyster mushroom mycelium in a petri dish on coffee grounds. Image: Tobi Kellner/Wikimedia Commons

To Stamets, this is about more than just a timber company’s bottom line. The economic argument is the first step in starting a deeper conversation about the potential for fungi to protect biodiversity, remediate the soil, replenish the carbon bank and increase overall forest health.

“We need to engage the ecosystem’s best skill-sets,” Stamets said. “And the best skill-sets that I know of are the fungal networks that inhabit all the landmasses, connect all the plants. They create the habitats and the soils that we benefit from.”

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