Forest Feed: How Trees Like, Share, & Communicate Through Mycelial Networks 🌲🍄
This is the story of how trees can talk, heal, warn, and nourish each other across vast distances using a silent and sophisticated social network powered by mushrooms.
A forest can be viewed as one giant organism made up of hundreds of thousands of individuals all interconnected.
While no single tree, shrub, or flower can “talk” — chemical messages are transferred with the help of symbiotic mushrooms living amongst the roots of forest-dwelling plants.
Mushrooms are just a small part of the fungi growing underground. Like an iceberg, we can only see a small portion of the behemoth that exists below the surface.
In Switzerland, researchers discovered a single honey fungus covering an area of 120 acres. This organism is estimated to be over 1000 years old.
Another sample in Oregon is estimated to be 2400 years old and covers an area of over 2000 acres with an estimated weight of 660 tons. This officially makes fungi the largest known organisms on Earth.
The vast mycelial network that makes up the underground part of mushrooms connects the many trees of the forest. This network of roots and mycelium form what the Peter Wohlleben (a legendary German forester-turned-ecologist) calls “the Wood Wide Web.”
Peter’s book “The Hidden Life of Trees” is a fascinating exploration of this topic — it’s definitely worth reading if you find this topic as interesting as I do.
Mycorrhizae: Fungi That Live Inside The Roots of Trees
To understand how and why trees communicate, we must first understand the symbiotic relationship that connects plants and fungi.
The symbiotic relationship between trees and fungi is a fascinating and vital aspect of the forest ecosystem. The partnership between trees and fungi is known as “mycorrhizae” — a mutually beneficial exchange between the roots of trees and the mycelium of mycorrhizal fungi.
There are two types of mycorrhizal relationships:
Endomycorrhizae — AKA “arbuscular mycorrhizae.” These species penetrate the root cells themselves, facilitating an even closer biochemical exchange between the fungus and the plant. This type is common in agricultural and grassland settings.
Ectomycorrhizae — These form a sheath around the roots and are typical in forest ecosystems, especially with trees like pines and oaks. The psychedelic mushroom, Amanita muscaria is an example of this type of mushroom.
Mycorrhizal fungi colonize the root systems of trees, forming a network of mycelium that extends far and wide into the surrounding soil. This mycelial network enhances the tree’s ability to absorb water and nutrients, such as phosphorus and nitrogen, from the soil. In return, the fungi receive carbohydrates and sugars produced by the tree through photosynthesis.
Some research has even found the mycelial network helps warn distant trees of encroaching pests and diseases in other parts of the forest.
This mutually beneficial relationship allows both the trees and fungi to flourish and grow stronger. It’s a shared economy where the ecosystem flourishes together without greed. Resources are shared, trash is recycled, and health is maintained across species boundaries.
There’s even some research that suggests the mycelial network has a form of primitive intelligence, complete with capacity for decision-making and memory.
The Mycelial Social Network
The Wood Wide Web starts with hub trees. These “hub” trees are the larger, older, stronger trees of the forest.
Hub trees fill large portions of the forest's canopy, and their roots stretch deep and wide below the ground. They photosynthesize far more than the younger, smaller trees of the forest — producing an excess of sugars and stored nutrients.
Nourishing The Weak
Trees use sugars produced through photosynthesis as “food” for growth. A portion of the excess food hub trees produce is given to the mycorrhizal fungi that connect the tree’s roots. This excess is then passed along through the wood wide web to nourish smaller, less established trees in the network.
Weaker trees and younger saplings that haven't quite reached the canopy don't produce enough energy through photosynthesis to thrive. Their roots haven’t reached the deep wells that make up the forest’s water table. Hub trees help these younger, weaker trees by directing excess sugar, nutrients, and unused water to their roots through the mycelial network.
There are even cases where hub trees have provided "life support" for sick or dying trees. Peter Wohlleben discovered this while observing the forests of Northern Germany. Every day, he'd walk past what he believed to be a series of stones covered in moss and lichen. One day, he decided to take his pocket knife and scrape away some of the moss. This revealed something extraordinary.
Expecting to find stone below the layers of moss and lichen, Peter was shocked to discover the bark of an ancient beech tree stump from a tree that had been felled over 400 years ago. He peeled a section of the bark away, only to find a green cambium layer. This stump was alive… But how? Without any foliage, this tree should have died long ago.
Peter's theory is that the surrounding, now mature, beech trees were the offspring of this ancient stump. Once, long ago, this "mother tree" would have fed its "children" the excess sugars it produced through photosynthesis. The tables have since turned, and it is now the strong, established children who care for their old, dying mother. Without them, she would have surely starved through the inability to photosynthesize her own nutrients.
Trees are like families, exchanging resources for the better of the group.
Mutual Protection
Not only do trees use the World Wide web to feed their young and support their elders, but they also use it to warn other trees of encroaching danger.
It’s been known for some time that trees communicate, warning others of pests.
Over four decades ago, scientists In the African Savannah noticed unusual behavior in a herd of giraffes. The herd was feeding on umbrella thorn acacias. In response to this, the trees began pumping a toxic substance into their leaves. The giraffes moved on to feed on other acacias in the area. However, the animals consciously avoided the trees in the near vicinity — walking past several stands of juicy acacia trees before feeding on a new, disconnected stand of trees over 100 yards away.
The scientists discovered that the victim trees that were being eaten sent a “warning gas” into the air that signaled neighboring trees of the threat. The neighboring acacias began pumping the same toxin into their leaves to prepare themselves against the threat.
The giraffes knew this, which is why, after tasting the bitter toxins, they were motivated to move to far-away trees. The animals were also observed moving to trees growing upwind. The warning gas excreted by the acacias is carried on the breeze, meaning that the trees living upwind remain oblivious to the threat.
These warning systems aren't restricted to the continent of Africa. Trees in Europe and North America also have systems in place for warning friend and family trees of encroaching pests. Many of these trees leverage the Wood Wide Web living underground to transmit these messages.
Oak trees, for example, produce bitter tannins in their bark, leaves, and seeds to kill or put off leaf-eating insects such as caterpillars.
When an oak tree is under attack, it pumps these tannins to the affected area. It also sends chemical signals and electrical impulses to its roots which are then carried through the underground network of “fiber-optic cables” that is the mycelial network. These warning signals are transferred to surrounding oaks in the forest. Once received, the trees start pumping tannins into their leaves in preparation for the attack.
The Wood Wide Web is a far more effective way of warning neighboring trees of danger. Unlike the acacias of the Savannah, which rely on the wind to transmit their warning signals, trees connected via mycelial networks can successfully warn surrounding trees regardless of weather conditions.
Healing The Sick
A single hub tree can be connected to hundreds of other trees, many of which are direct descendants that have grown from its own seeds.
When a tree within a connected group becomes infected by pests, disease, or harmful fungi, chemical signals are sent through the mycelial network. These signals often act as a warning — allowing other trees in the network time to prepare to resist the encroaching threat. These signals may also be received as a “cry for help” from the affected tree.
Rather than cutting off the weak, dying tree from the network, the hub tree may send resources to help it fight the sickness. This could come in the form of nutrients to help manufacture defensive chemicals, instructions on how to synthesize the perfect cocktail to repel or kill the current threat, or by sharing these chemicals directly.
An example of this powerful healing potential was reported by a group of biologists exploring a remote forest in British Columbia. A centuries-old Douglas fir, known to local researchers as "The Sentinel," faced a severe threat from an invasive bark beetle infestation.
As the beetles began to burrow and compromise the tree’s health, something remarkable happened.
Biologists noticed an increase in nutrient flow toward The Sentinel — specifically nitrogen and phosphorus elements required to produce defensive resins used to fight the infection caused by the beetles.
This wasn't a coincidence — it was a concerted effort by the surrounding trees, all interconnected through the mycelial network. These trees, some of which grew over 100 feet away, were channeling extra resources to aid the infected tree.
The forest mounted a collective defense strategy — all orchestrated through the mycelial network to fight the devastating onslaught of the bark beetle through the sharing of nutrients and biochemical instructions The Sentinel should use to make its own cocktail of defensive resins.
The Critical Role of Complex Forest Networks
The complex network of mycelium underground helps entire forests survive and thrive, even through times of hardship.
Without the Wood Wide Web, forests suffer. When trees fail to communicate, they lose their ability to warn each other about incoming pests, nourish the young, or treat the sick.
Contrary to what we once believed, the forest isn't full of competition. Instead, trees work together as a collective, talking and sharing resources to better the health of the whole forest rather than one single tree or species.
There's a reason monocropping is so prone to disease and devastation. The forest ecosystem requires diversity to thrive. Removing this diversity and replacing it with rows of single-species silences the forest, making it easy for disease to spread.
It's important to understand why and how trees communicate if we are to move toward a more sustainable future. Rather than creating plantations, wood should be harvested sustainably from healthy forests. The clearings created from harvesting should be allowed to self-seed, letting the forest find its balance and form new networks.
Trees and mushrooms are more than just a commodity. They must be allowed to fulfill their critical social role within the forest to ensure ecological resilience and long-term continuity.
Further Reading:
The Story of P. tampanensis: Psychedelia, Murder, & the Evolution of Magic Truffles
Eager to Pick Magic Mushrooms? Here’s How to Know When It’s Harvest Time.
The Evolution of Psychedelic Mushrooms with Dr. Jason Slot (🎙 Podcast)
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