Do Trees Communicate Underground?

Forests appear silent. Trees stand motionless, seemingly isolated, each living its own slow life. Yet beneath the soil, a complex network may be at work—one that connects roots, fungi, and nutrients in ways that resemble communication. Some scientists argue that forests behave less like collections of separate trees and more like interconnected communities.

This idea fascinates researchers because it challenges how we think about plants. If trees share information, resources, or warnings, then forests may be more cooperative than competitive. The question is not whether trees move or speak in human terms, but whether they exchange signals that influence each other’s survival.

The Hidden Network Beneath the Soil

Beneath every forest lies a vast network of fungi known as mycorrhizae. These fungal threads extend from tree roots into the soil, weaving through the underground environment. Mycorrhizae help trees absorb nutrients such as nitrogen and phosphorus, while trees provide fungi with sugars produced through photosynthesis. This mutualistic partnership is ancient and widespread.

What makes mycorrhizal networks interesting is not just their ability to transport nutrients, but their ability to connect different trees. In some forests, a single fungal network may link dozens of trees, forming what ecologists call the “wood wide web.”

Resource Sharing

One hypothesis suggests that trees share resources through these underground connections. If a tree in shade struggles to photosynthesize, neighboring trees might transfer sugars through the fungal network. Experiments have shown that carbon compounds can move from one tree to another, especially between trees of the same species or between parent and offspring.

While the exact reasons for this transfer are debated, the phenomenon itself is measurable.

Warning Signals

Another line of research suggests that trees may use chemical signals to warn neighbors about herbivores or disease. For example, when insects attack a tree’s leaves, the damaged tree may release airborne signals that prime nearby trees for defense. Underground networks may provide another channel for these signals, potentially allowing information to move even without wind.

These warnings are not conscious messages. They are chemical responses shaped by evolution. Still, they reveal the possibility that plants do not simply react to their own circumstances but respond to others.

Cooperation or Competition?

Not all scientists agree that resource sharing implies cooperation. Some argue that trees connected through fungal networks may not “choose” to share, but simply leak nutrients that fungi redistribute. In this view, fungi act as intermediaries that maximize their own benefit, not the benefit of the trees.

Other researchers see the system as a marketplace. Trees “pay” fungi in sugars, and fungi provide nutrients in return. Sharing emerges from supply and demand, not altruism.

The Mother Tree Hypothesis

One of the most intriguing ideas in forest ecology is the “mother tree” hypothesis. According to this model, older and larger trees act as hubs within underground networks, distributing nutrients to younger seedlings. If true, this could help explain why some seedlings survive in dense shade while others fail.

However, the hypothesis remains contentious. Some ecologists support it; others argue it oversimplifies a complex and dynamic system.

Why This Idea Captures Imagination

The idea that trees communicate resonates because it challenges the notion of individuality. Forests may be more cooperative than previously assumed. The concept also echoes human understanding of social networks, raising philosophical questions about intelligence, community, and life.

Yet researchers urge caution. Words like “communication” and “friendship” carry human meanings that may not apply to plants. Scientific descriptions must avoid metaphor turning into conclusion.

What Counts as Communication?

From a biological perspective, communication occurs when one organism produces a signal that alters the behavior or state of another. If fungi transmit chemicals that influence how trees grow, allocate resources, or defend themselves, then some form of communication may indeed be taking place—even without consciousness or intent.

Plants already communicate through chemicals in the air and soil. Underground networks simply expand the medium.

The Forest as a System

Whether cooperative or competitive, forests function as systems. Individual trees alter light, water, and soil conditions. Fungi redistribute nutrients and structure underground ecosystems. Animals and microbes interact with both. The result is an environment where no organism truly acts alone.

Understanding forests as systems does not require trees to possess intelligence or agency. It requires recognizing that life is shaped by interactions.

Summary

Trees may not communicate like humans, but evidence suggests they exchange resources and chemical signals through underground fungal networks. These interactions influence growth, defense, and survival. The forest, seen from below, is less a collection of isolated individuals and more a connected web shaped by cooperation, competition, and shared environments.