For years, the idea that trees “talk” to one another underground has captured the public imagination. It is an appealing image: a forest not as a crowd of separate organisms competing for light and water, but as a connected living system, quietly exchanging nutrients and chemical signals beneath the soil. Scientists do have strong evidence that many plants are linked by fungal partners in the ground. But the more researchers study those underground networks, the more careful they have become about what, exactly, they mean. The science is not collapsing. It is getting more precise. And that precision is making the story more interesting, not less. According to a recent Nature review on misinformation and overinterpretation around common mycorrhizal networks, underground fungal connections in forests are real, but some of the most popular claims about how they work have outrun the evidence.
At the center of this story are mycorrhizal fungi, which form symbiotic relationships with plant roots. In exchange for sugars made by plants through photosynthesis, the fungi help plants access water and nutrients from the soil. These fungal structures can spread widely through the ground, sometimes linking multiple plants into what researchers call common mycorrhizal networks. A 2025 Nature paper on mycorrhizal fungal richness notes that mycorrhizal fungi associate with more than 80% of plant species and can make up a substantial share of living microbial biomass in soils. That alone makes them ecologically important, even before the more ambitious questions about communication and cooperation begin.
The Underground Network Is Real
The basic scientific point is not especially controversial. Forest soils are full of fungal hyphae, and many of those fungi connect with plant roots in ways that affect growth, nutrient access, and survival. In some cases, those networks may physically link multiple plants at once. A broad Frontiers review of common mycorrhizal networks describes these underground systems as pathways through which nutrients and signaling compounds can potentially move between connected plants. That means the popular idea of forest connectivity is not invented. It is grounded in real biology.
But “connected” does not automatically mean cooperative in the human sense, and it certainly does not mean forests behave like intentional communities. The most serious researchers in this field have become increasingly careful about avoiding language that implies too much purpose or too much certainty. A fungal network can connect plants without functioning as a benevolent social system. It can help one plant, disadvantage another, or produce outcomes that vary depending on species, age, soil conditions, and fungal partners. What looks like communication from one angle may look like resource competition or opportunistic exchange from another.
The “Wood Wide Web” Is Powerful — and Easy to Overstate
No phrase has done more to popularize this topic than “wood wide web.” It is memorable, elegant, and not entirely wrong. But it also encourages a misleading analogy. The internet was built to transmit information intentionally. Forest fungal networks were not. They evolved through ecological relationships between roots, fungi, microbes, and soils. That does not make them less remarkable. It just means scientists have to be more disciplined than the metaphor.
That is exactly the point made in the Nature critique of positive citation bias in mycorrhizal network research. The authors argued that popular media coverage and even some scientific citations had inflated the evidence for sweeping claims about widespread resource sharing and “mother tree” behavior. Their concern was not that underground networks do nothing, but that forest science was at risk of drifting from evidence into mythology. That distinction matters because once a scientific idea becomes culturally beloved, it can become harder to question without sounding anti-nature or anti-cooperation.
And yet the correction here is not a debunking so much as a refinement. Scientists are not concluding that forests are just collections of isolated individuals after all. They are concluding that the networks under forests are biologically real, ecologically consequential, and more complicated than the most optimistic popular narrative suggests. That is often what mature science looks like: not a reversal, but a narrowing from broad metaphor to better-supported mechanism.
What the Networks Actually Seem to Do
One of the more persuasive findings in recent years is that fungal networks can influence who survives and who dominates in forests. A Nature Communications study on soil fungal networks and seedling demography found that access to fungal hyphae supported seedling survival and growth for some tree species, especially those associated with ectomycorrhizal fungi. That does not mean every connected tree is being “helped” by neighbors in a moral sense. It does mean underground fungal networks can affect forest structure in measurable ways.
This is one reason the subject matters well beyond botanical curiosity. If fungal associations help determine which seedlings thrive beneath adult trees, then the underground biology of forests is partly shaping regeneration, competition, and long-term composition. That moves the subject from poetic metaphor into hard ecology. Forests may not simply be organized by what happens above ground—light, canopy gaps, rainfall, herbivores—but also by hidden interactions below ground that influence which species can establish themselves and persist.
Scientists are also finding that mycorrhizal relationships help structure forests at larger scales. A recent Science Advances study on mycorrhizal symbioses and tree diversity linked different mycorrhizal strategies to patterns of local tree diversity across global forests. Another Nature Communications paper on mixed mycorrhizal strategies found that forests containing different mycorrhizal types can show higher productivity under some conditions. These studies do not prove that trees are “cooperating” in a simple way. But they do show that fungal partnerships are central to how forests function, diversify, and allocate resources.
The Debate Over “Mother Trees”
Perhaps the most famous version of this idea is the “mother tree” hypothesis: the suggestion that older, larger trees may support younger seedlings through shared underground fungal networks. It is a compelling concept, and some published work has suggested resource transfer can occur under certain conditions. But the evidence remains more contested than many readers realize.
That tension is captured in both the Nature critique of overinterpreted network claims and a New Phytologist re-examination of the mother tree hypothesis, which argues that the current evidence for substantial carbon sharing from mature trees to seedlings through ectomycorrhizal networks has often been overstated. The important point is not that mature trees are irrelevant. They may be ecologically crucial for many reasons, including shading, soil stabilization, microbial communities, and habitat structure. The point is that one specific claim—direct nurturing through underground carbon transfer—requires a higher evidentiary bar than popular retellings sometimes acknowledge.
This does not make the underground world any less fascinating. In fact, it makes it more scientifically valuable. Forests are not turning out to be fairy tales of universal generosity, nor are they simple battlefields of ruthless competition. They are mixed systems in which cooperation, competition, opportunism, mutual dependence, and environmental constraint all interact at once. That is a more difficult story to tell, but also a truer one.
Why This Changes Biology More Broadly
The implications of this research go beyond forests because it challenges one of biology’s oldest habits: the instinct to treat organisms as fully separate individuals whose most important interactions happen at visible scales. Underground network research instead suggests that many living systems are partly constituted by relationships—between roots and fungi, plants and microbes, hosts and symbionts, competition and exchange.
That does not erase individuality. Trees are still trees, fungi are still fungi, and not every network creates a meaningful shared system. But it does complicate older boundaries. A forest can no longer be understood only as a collection of trunks and leaves. It must also be understood as an ecosystem of hidden associations, many of which influence growth, resilience, carbon storage, and recovery from stress. Even when the strongest public claims are scaled back, the conceptual shift remains profound: the living world is more relational than it appears from the surface.
This also has practical consequences for conservation and restoration. If fungal partnerships shape establishment and survival, then replanting trees without thinking about soil communities may miss a large part of what makes forests function. Research summarized in a recent Nature study on mycorrhizal colonization under aridity suggests that microbial cooperation can help support mycorrhizal colonization in dryland tree establishment. That implies that forest recovery under climate stress may depend not only on the right tree species, but also on the invisible microbial relationships that allow those species to take hold.
A Better Story Beneath the Forest Floor
So what are scientists learning about the underground networks connecting forests? First, that those networks are real and ecologically important. Second, that they are not as simple or as sentimental as the most popular versions of the story imply. And third, that the real science may be more transformative than the metaphor that first made it famous.
The deeper lesson is not just that trees are connected. It is that forests are systems of exchange and dependence whose most important interactions are often hidden from view. The underground world beneath a forest floor is not a magical internet, nor is it a trivial footnote to what happens above ground. It is one of the places where modern biology is being forced to think harder about what connection, cooperation, and individuality actually mean. And that may be the most important discovery of all.
