The 'Wood Wide Web': How Trees Talk Underground

Symbolic image: mushroom in the forest · Photo: CC BY 2.0

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A forest looks like a collection of individual trees. But underground, many of them are connected – through a fine web of fungal threads that researchers half-jokingly named the "Wood Wide Web", echoing the World Wide Web.

The fungi wrap themselves like a mesh around the trees' roots and connect them. Water, sugar and nutrients flow through this network. Large old "mother trees" can help supply younger ones this way. Some studies even suggest trees exchange warning signals through the network, for instance when pests attack.

For the fungi this is not altruism but a trade: they receive sugar from the trees' photosynthesis and give back nutrients from the soil that the tree roots could not reach alone.

Important context: how far the trees' "communication" really goes is disputed in research. Some scientists warn against romanticising the picture – the nutrient exchange is proven, the deliberate "agreement" between trees is not.

Why it matters: it changes our view of the forest – away from a struggle of individual trees toward a connected system. That also has consequences for how we should protect and reforest woodlands.

Own synthesis based on publicly available ecological research. Disputed points are marked as such.

Symbolic image · Photo: Amanita muscaria, CC BY 2.0, via Wikimedia Commons