Max G. Levy writes:

One Tuesday in June 2025, a white Chevy Suburban set off down the northernmost highway in North America. The sun of Alaska’s polar summer hadn’t set in 40 days, and it wouldn’t set again for another 35. But for Michael Van Nuland, the biologist in the driver’s seat, time was already running out.

The SUV, packed with four days of fieldwork essentials — rubber boots for mucking in marshes, GPS for centimeter-level precision, a steel tube for extracting soil cores from permafrost — growled along the Dalton Highway, which sews an asphalt-and-gravel seam through the tundra of Alaska’s northern coast. Through the window, the lack of visible trees suggested a barren landscape, but looks are deceiving. The miles of sedge and duvet-thick moss formed the basis of a feast for seasonal caribou, grizzlies, muskox, and roughly 200 bird species.

Van Nuland was more interested in what was happening underground, where sprawling systems of fungal threads — from microscopic ducts to arteries thick as yarn — extended dozens of feet horizontally in all directions. By connecting plant roots and circulating nutrients, this dense, networked scaffold sustained life above the surface.

“Some people just see dirt as dirt. But it’s a living, breathing system,” said Van Nuland, the lead data scientist of the nonprofit Society for the Protection of Underground Networks (SPUN). “The complexity you see in a forest — the layers of canopy, the different species of birds and insects … You’re walking over an equally or possibly even more complex system below ground.”

This system’s architect was the subject of Van Nuland’s study: mycorrhizal fungi, a group of evolutionarily far-flung, soil-dwelling microbes whose ever-growing appendages extract nutrients and water from their surroundings. Those surroundings include nearby plants. The fungi’s pale, thread-like “hyphae” burrow through the soil until they find plant roots to connect with. Then, the parties can trade. From the fungus, the plant accepts scarce nitrogen and phosphorus that its own roots struggle to reach; the fungus takes the plant’s carbon to further grow and colonize the soil.

Across the century since their discovery, mycorrhizal fungi have been considered parasites of plant roots and, later, passive infrastructure that served plants’ interests. But studies from this decade that used advanced techniques in robotics and imaging suggest that they are active merchants that control their fates and influence the fates of others. [Continue reading…]