TREES TALK: STORIES OF UNDERGROUND FOREST NETWORKS
We often think of trees as silent, solitary giants... but in reality, they’re part of an incredible underground network that allows them to communicate, share, and survive together. This hidden system is powered by something most of us never see: fungi.
ANCIENT ALLIANCES
Mycorrhizae (singular: mycorrhiza) are microscopic fungal threads that form a long-term, mutually beneficial partnership with plant roots in the rhizosphere, the thin layer of soil surrounding a plant’s root system.
Beneath the forest floor, these so-called “fungus roots” (from the Greek mykes meaning fungus, and rhiza meaning root) weave individual trees into a much larger underground network. These fungi don’t simply grow near roots: they fuse directly with them, forming a symbiotic relationship.
The fungi extend far into the soil, increasing the plant’s access to water and hard-to-reach nutrients like phosphorus and nitrogen. In exchange, the plant supplies the fungi with sugars produced through photosynthesis, providing energy for the fungi to thrive.
What’s especially remarkable is that this relationship doesn’t stop at one plant. These networks can link multiple trees together, even those of different species, sizes, and ages. In effect, each tree becomes a node in a vast underground network, a biological system so intricate and efficient, it’s often referred to as the Wood Wide Web.
WHAT ARE TREES SAYING?
Here’s where things get fascinating. Scientists have discovered that through this network, trees can:
Share nutrients: Stronger trees send carbon or nutrients to weaker or younger ones, especially in times of stress.
Send warnings: When a tree is attacked by pests, it can signal its neighbours to boost their chemical defences. Think of it as a forest-wide “heads up.”
Prioritize family: Trees seem to recognize their own offspring and preferentially support them, sending more resources their way.
This changes how we view forests—not as a competition for sunlight and space, but as a cooperative, social network where survival is shared.
FUNGI OR FUN GUYS?
Though we often associate fungi with rot and decay, many types are here for a good time, playing an essential role in forest health. Without mycorrhizal fungi, trees would grow slower, be more vulnerable to disease, and struggle during droughts.
In fact, over 90% of land plants depend on fungi to survive. That includes trees, wildflowers, even many of the crops we eat.
And here’s something that surprises most people: those mushrooms you see dotting the forest floor? They’re not the whole fungus. They’re just the fruiting bodies; the reproductive organs that release spores (kind of like seeds).
The real fungus is below ground, made up of an intricate network of microscopic threads called hyphae. These threads grow outward in every direction, exploring, absorbing, and connecting with roots. When enough of them cluster together, they form what’s called a mycelium, a massive underground web that can stretch for kilometres.
It’s a bit like spotting an apple on a tree. The mushroom is just the visible part. The real organism (the roots, trunk, and branches) is hidden out of sight, quietly doing the hard work.
PROTECTING NETWORKS
The health of a forest is not measured only by what we can see, such as soaring trees, vibrant leaves, and scenic lookouts. It also depends on what is happening underground, within the hidden world of roots and fungal threads.
When soil is damaged or these delicate systems are disrupted, the effects extend far beyond a single tree. The entire network that keeps the forest healthy, resilient, and connected can be compromised.
Here are a few ways you can help protect these underground allies and the ecosystems that depend on them:
Stay on designated trails: Walking off the trail can compact the soil and damage delicate fungal networks.
Avoid disturbing the soil unnecessarily: In natural areas, leave soil, plants, and other natural features undisturbed.
Support native species: Native trees and fungi have evolved alongside one another. Planting and protecting native species helps sustain these important relationships.
Donate or volunteer: Land trusts like the Algoma Highlands Conservancy protect entire ecosystems, from the treetops to the roots below.
THE FOREST IS LISTENING
At the Algoma Highlands Conservancy, our focus extends beyond protecting scenic views and well-known landmarks. We are committed to conserving the entire forest system, including the complex and often overlooked ecosystems beneath the surface.
A forest’s health depends not only on what we see above ground, but also on the intricate networks below. Formed by roots, fungi, and soil organisms, these underground systems are essential to the survival, resilience, and long-term stability of forest ecosystems.
By understanding and protecting these systems, we can make better-informed decisions about land use, recreation, restoration, and stewardship.
A forest is not simply a collection of trees. It is a living system whose many parts are interconnected and interdependent. As we continue to learn more about how forests function, it becomes increasingly clear how much is at stake, not only for biodiversity, but also for climate stability, clean water, and future generations.
If you value this kind of work, we
invite you to support it.
Whether through membership, volunteering, or donation, your contribution helps protect the full picture from canopy to forest floor.
