The foothills of California’s Sierra Nevada, Oregon’s Willamette Valley and the Columbia River Gorge in Washington and Oregon all have something in common: a sprawling underground microbial network. Every spring, the West’s mushroom hunters visit their favorite “secret” spots in these forests, searching for gourmet species like “spring kings” (Boletus rex-veris) in the Pacific Northwest and Northern California and Oregon black truffles in the Gorge.
The Underground Atlas, a new model of the worldwide distribution of mycorrhizal, or network-forming, fungi, shows that the fungi in these and other places need protection. Created by researchers at the Society for the Protection of Underground Networks (SPUN), the atlas estimates that 90% of mycorrhizal biodiversity hotspots lie outside protected areas.
The Western U.S. is particularly rich in ectomycorrhizal fungi, which form symbiotic relationships with trees and shrubs and are found in conifer forests from the Rockies to the Sierra Nevada. They’re also found in the Pacific Northwest, where they partner with Douglas firs, western hemlocks and cottonwoods.
Almost 5% of the world’s ectomycorrhizal fungi hotspots are located in the Western U.S. Like their counterparts worldwide, the majority of Western fungi — and the plants that depend on them — are vulnerable to industrial agriculture, infrastructure development and other human disruptions of the soil.
ROUGHLY 90% OF PLANT species on Earth form mutually beneficial relationships with mycorrhizal fungi. Fungal filaments connect with plants’ roots, encouraging an exchange of carbohydrates and minerals that enhances plant growth, nurtures soil health, and even promotes carbon sequestration — mycorrhizal fungi alone store an estimated 13 billion tons of carbon, or about a third of annual global carbon emissions, underground worldwide.
“Everywhere you see a plant, this type of interaction is happening,” said Michael Van Nuland, lead data scientist at SPUN.
Van Nuland calls mycorrhizal fungi the “circulatory system of the planet” because they are so effective at moving nutrients between plants and soil. But fungi have received far less attention and protection than plants and animals. “We know native plants, we know native animals, but we don’t know native fungi,” said Aaron Tupac, a mycologist and community educator in Los Angeles, California. Fungi weren’t even recognized as a separate kingdom of life until 1969; before then, they were considered to be part of the plant kingdom.
“We know native plants, we know native animals, but we don’t know native fungi.”
Kabir Peay, a biologist who studies fungi at Stanford University, sees the public attention captured by projects like SPUN as an opportunity. “I think we’re in a really unique place where we start to have the momentum to build a case for the conservation of organisms that have really not been genuinely appreciated very much in the past,” he said.
Though momentum may be building, the progress isn’t linear. In 2022, California launched the first state-funded effort to document its fungi, part of a larger effort to conserve 30% of the state’s lands and waters by 2030. CA FUNDIS documented and preserved more than 10,000 different fungi species for further research before losing funding in 2023. Funding for other important mycorrhizal fungi work is currently in danger of lapsing, including support for the world’s largest living soil fungi library at the University of Kansas.
While protected areas like parks can benefit fungi, Van Nuland acknowledges that “you can’t set up national parks everywhere for every ecosystem.” But fungal diversity can be protected no matter where it occurs. Land managers can allow more woody debris to remain on the landscape as a food source for fungi; anyone can improve their backyard’s soil health by composting.
Pairing native plants with their fungal counterparts can also increase the success of restoration efforts, Van Nuland said. Researchers with SPUN plan to sample Joshua tree habitat this spring and identify fungi associated with the trees. Those species, they hope, can then be incorporated into the Joshua tree transplantation and restoration efforts highlighted by the California Legislature in 2023 and finalized in a sweeping state conservation plan for the species in the summer of 2025. Meanwhile, the Gabrieleño Band of Mission Indians has been working with fungi to remove heavy metals and pollutants from contaminated soil in Los Angeles.
Finally, scientists say fungal conservation needs to include the kinds of active cultivation strategies already in use for flora and fauna. Nurseries raise threatened plant populations and hatcheries grow salmon, but “we are definitely not even close to that for thinking about the conservation of fungi,” Peay said.
Climate change is already altering ecosystems faster than scientists can document their fungi, Tupac said, so conservationists shouldn’t wait until fungal species are threatened or endangered to take decisive action or unlock financial support. “My colleagues in the fungal conservation world are saying, ‘Perhaps we don’t have to just think about what is rare and scarce,’” they said. ‘“Why not make the case for protecting what is abundant?’”
This story is part of High Country News’ Conservation Beyond Boundaries project, which is supported by the BAND Foundation and the Mighty Arrow Family Foundation.
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