Science Matters – Wood Wide Web

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It’s well known that walking in the woods – breathing clean air, treading soft paths, inhaling forest fragrances, appreciating the silence and the dappled sunlight – can calm the nerves.  But read ‘The Hidden Life of Trees’, by Peter Wohlleben, a Rhineland forester, and a walk through the woods becomes an even more magical experience.

Wohlleben, who manages an ancient deciduous forest, shows how trees secretly communicate with each other, how parent trees protect and nurture their young, share nutrients and support the sick. All quite amazing, but most fascinating for me is the underground ‘wood wide web’.

Back in the 1990s forest ecologists wondered why removing wild species from planted forests had a detrimental effect on the planted trees.  The answer is that weeding destroys underground connections through which trees communicate. Tree roots extend about twice as far underground as the tree’s canopy spreads above ground, so inevitably roots of forest trees intermingle. But it is fungi that actually forge the communication channels between them.

Fungi are neither plants or animals. They feed by digesting living or dead organic material.  We only see their fruiting bodies that pop up in Autumn, but in soil their thin filaments form a huge, dense network called a mycelium.  Scientists in Oregon, US, discovered a single 2,400-year-old fungus extending over 2,000 acres and weighing 660 tons – the largest living organism in the world.

Actually, this particular giant is not tree-friendly, but other similar fungi form symbiotic relationships with trees. By penetrating tree roots they obtain sugar and other carbohydrates, sometimes taking up to a third of a tree’s energy supply.  In return, fungi clear pollutants from trees and prevent bacterial and lethal fungal attack. Via mycelia, trees share water and nutrients obtained from a vast area.

Astonishingly, some trees also send chemical messages via the network warning others of imminent insect attack.  They then respond by pumping insect repellents into their leaves.

Next time you go walking in the woods spare a thought for what’s going on beneath your feet.


Trees are more connected than we might imagine. 06_a52A83Trees01