National Tree Week

National Tree Week runs from 26 November to 4 December this year. The theme is ‘hidden connections’, celebrating the life support system which sustains our trees. From roots, to soil, to fungi and the nutrients they provide.

In a forest recently, I took a series of photos looking up. A ground level perspective in contrast to the bird’s eye view. I was particularly interested in capturing the underside of various fungi, with the trees above. The relationship between tree roots and fungi is a symbiotic one. Each relies on the other for survival.

 

Networks

Fungi are the fruit of vast networks of fine underground threads, mycelium, which cover large areas across the forest floor. By intertwining with tree roots, mycelium share water and nutrients they collect, in exchange for carbon and sugars, which they need to sustain their fungi. The mycelium connection between roots enables trees to communicate directly with each other. And mycelium don’t limit their connections to trees. They create an extensive subterranean network between trees and other plants, known as mycorrhiza, meaning fungus-root.

Charles Darwin spent the second half of his career studying plants. One of his final books, published with his son (Francis), The Power Of Movement Of Plants, proposed the root-brain hypothesis. Charles Darwin postulated that roots behave like brain-like organisms. He suggested they control many essential functions of plants, including plant to plant communication.

Examples of communication between trees include using the mycelium connections to monitor the health of their network. Saplings struggling for sustenance are identified by more mature trees, and extra nutrients are shared through the mycelium network. If a tree is under threat from disease or insects (for example), the message spreads quickly through the fungal network. Healthy trees can prepare their defences, and dying trees might use the connections to share resources to help strengthen neighbouring trees.

Parent trees can identify their own seedlings, and use the network to divert resources to support their seedlings above other young trees. If the parent tree identifies that their seedling isn’t in a good place to grow, they might even use the connections to deny nutrients and water, to kill off their young.

Trees are not just fascinating, but are fundamental to the health of our planet, and essential for sustaining life on Earth. Find out more about National Tree Week through the Tree Council.