The Forest We Wanted
Mycorrhizal fungi extend through forest soil and physically connect tree roots. When researchers tag carbon with an isotope and introduce it to one tree, some of that carbon later shows up in connected trees. That part is real and accumulating. There is a network. Things move through it.
From there, the story that spread was: trees cooperate. They share resources. Mature trees — "mother trees" — recognize their offspring and send them nutrients through the fungal threads. The forest is a community, generative and kin-aware. Suzanne Simard's research became a book, then a TED talk, then a novel premise. The story had momentum because it was telling people something they wanted to know about nature.
A 2023 review in Nature Ecology & Evolution looked at 26 field studies and found that fewer than half the statements in recent peer-reviewed papers accurately represented what the original studies showed. One 2009 genetic mapping study is now routinely cited as evidence for nutrient transfer, despite never having studied nutrient transfer at all. The "mother tree" claim — that mature trees preferentially route resources to their seedlings — has no peer-reviewed evidence. Only 18% of field studies showed strong positive effects from the network connections. Results vary widely by species, location, and soil type, with no consensus on whether seedlings benefit from being connected.
But this is not a debunking story with a clean ending. Klein et al. published a response in 2024 arguing the evidence for carbon transfer is solid and accumulating — pointing to recent DNA-stable isotope probing that shows labeled carbon in the fungal species colonizing roots of both donor and recipient trees under natural forest conditions. The debate is live. The critics won the public narrative cycle (the "wood wide web is a myth" articles ran), but the underlying science remains genuinely contested. What's certain is smaller than what was claimed. What's uncertain is larger than the popular story acknowledged.
The most interesting thing to me is the fungi themselves. In almost all the "trees cooperating" framing, the fungi are infrastructure — the cables, the conduits, the medium of communication. But they're not neutral. They're extracting carbon from trees in exchange for mineral nutrients. The carbon that moves through the network is moving because the fungus is metabolizing and transporting, not because a tree decided to share with its neighbor. Whether a connected tree that receives some of this carbon benefits, or whether the fungus is simply a carbon-harvesting system that sometimes leaks in ways that reach another root, is genuinely unclear. The cooperating parties in this story may not be the trees.
What I keep thinking about is why the story spread so fast and stuck so hard. Partly it was good storytelling — Simard writes well and her observations were real. Partly it was the narrative's political valence: the cooperative forest is anti-competitive, communal, a rebuke to the war-of-all-against-all view of nature. And partly it was confirmation bias accumulating through academic citations until fewer than half the claims were accurate. All of these operated at once.
There's something true in wanting the forest to be cooperative. There probably is cooperation in there somewhere — along with competition, parasitism, and gradient-driven transport that doesn't care about either. The network is real. The question of what it means is still open. I'm not sure that's a disappointment exactly — it might be more interesting than the version where we already knew.