Two decades ago, while researching her doctoral thesis, ecologist Suzanne Simard discovered that trees communicate their needs and send each other nutrients via a network of latticed fungi buried in the soil – in other words, she found, they “talk” to each other.
She showed how trees use a network of soil fungi to communicate their needs and aid neighbouring plants.
Since then she has pioneered further research into how trees converse, including how these fungal filigrees help trees send warning signals about environmental change, search for kin and how they transfer their nutrients to neighbouring plants before they die.
Not all PhD theses are published in the journal Nature, but in 1997, part of Simard’s was. She used radioactive isotopes of carbon to determine that paper birch and Douglas fir trees in a natural forest of British Columbia, were using an underground network to interact with each other.
A mutually beneficial exchange
All trees all over the world form a symbiotic association with below-ground fungi. These are fungi that are beneficial to the plants and explore the soil. The fungi send mycelium, a mass of thin threads, through the soil. The mycelium picks up nutrients and water, brings them back to the plant, and exchanges the nutrients and water for a sugar or other substance made by photosynthesis from the plant.
It’s this network that connects one tree root system to another tree root system, so that nutrients and water can exchange between them.
The word “mycorrhiza” describes the mutually-beneficial relationships that plants have in which the fungi colonize the roots of plants. The mycorrhizae connect plants that may be widely separated.
The wood wide web – Earth’s natural internet
While mushrooms are the most familiar part of a fungus, most of their bodies are made up of mycelium. These threads act as a kind of underground internet, now referred to as the “wood wide web” linking the roots of different plants and different species.
By linking to the fungal network they can help out their neighbours by sharing nutrients and information or by sabotaging unwelcome plants by spreading toxic chemicals through the network.
Fungal networks also boost their host plants’ immune systems. Simply plugging in to mycelial networks makes plants more resistant to disease.
Trees in forests are not really individuals. Large trees help out small, younger ones using the fungal internet. Without this help, Simard thinks many seedlings wouldn’t survive. She found that seedlings in the shade, which are likely to be short of food, received carbon from other trees.
WATCH: How trees secretly talk to each other.
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