For a long time we have believed that plants and trees are individuals, standing alone in a never ending competition for food and light, incapable of communicating with each other or interacting with the world around them. I mean would you actually believe it if someone told you that trees can communicate? Because funnily enough they can, just not exactly in the same way that we do.
Science is radically changing the way that we think about trees, which happen to be far more astonishing and sophisticated than we previously thought. Trees – especially in forests – have an incredible ability to act like a single organism, and even communicate (in a way likened to how humans communicate via the internet) using chemical compounds and electrical signals which are transmitted through vast interconnected networks of fungi which form symbiotic relationships with trees.
This peculiar partnership has been taking place for millions of years, and it depends a lot on the incredible abilities of fungi. Fungi are not exactly like plants or animals, but somewhere in between the two. Their structure makes them more similar to insects, due to a substance found in their cell walls (chitin) which is never found in plants. Fungi cannot photosynthesise and instead depend on organic partnerships with other living organisms which they can feed on.
The term, first coined the “wood wide web’ by the journal Nature, refers to networks of fungi which infiltrate the forest floor on an unbelievable scale. The largest organism known to man is a fungal network, which covers an area of 8.4 square kilometres and is believed to be 2,400 years old.
Fungi have spindly filaments which entwine themselves into the fine hairs of the root systems of trees forming a mycorrhiza, and thus – like fibre optic cables – connect trees to one and other beneath the ground, like a giant network of computers. The reason fungi has adapted to interact with trees in this manner is actually beautifully simple: fungi can increase the mineral uptake of host trees which they are connected to and filter out harmful pollutants from the soil. In exchange the fungi receive a share of the host’s sugars – up to one third in some cases.
The mycorrhiza network branches out, weaving its way through the soil into the roots of baby saplings and ancient parent trees alike, extending the reach of any single tree far beyond it’s own root system. According to Peter Wohlleben in ‘The hidden life of trees’, a single fungus can span an entire forest covering many square miles. This network enables trees to send chemical (systemic response chemicals or SRC’s) and electrical signals from one tree to the next, sharing news about bugs, drought and other dangers. Amazingly, just one teaspoon of forest soil contains many miles of fungus filaments.
I know what you’re thinking (this is insane) but hang on, this baffling symbiotic relationship doesn’t stop there… Fungi also actively manage nutrient resources across the network. This was tested in Suzanne Simard’s 1997 paper by supplementing trees with a naturally occurring traceable isotope (13CO2). The isotope was seen to be transferred from the leaves of a healthy donor tree to the roots of undernourished trees through the mycorrhizal network. In other words, the fungus was redistributing surplus nutrients to the less fortunate members of the network.
It’s not fully understood why trees act like a community, but it’s obviously not in a forest’s best interest to lose its weaker members because if that were the case, gaps would emerge which could disturb the sensitive microclimate of the forest leading to to lower levels of humidity and altered light conditions; both of which could hinder the development of the overall ecosystem and decrease the nutrient pool for all symbionts.
In the symbiotic community of the forest, it’s not only trees which share information this way but also other plants, grasses and shrubs. Unfortunately, these systems seem only to occur in well developed forests, limited often to forests which have not been disturbed by humans for a long time. When we investigate our fields and agricultural land where pesticides have been frequently used, relationships between plants and fungi are much less prevalent. Maybe we can grow a little more organically and assist the wood wide web in developing more communities of trees and fungi.