Do trees really talk through a 'wood wide web'?
Fungi weave through forest soil and link to tree roots, trading nutrients for sugar. Popular books describe trees using this network to feed their young and warn neighbours. A 2023 review found the fungal connections are real, but the evidence for trees deliberately sharing and signalling is much weaker than we've been told.
Most plants live in partnership with fungi. In a mycorrhizal relationship, fungal threads called hyphae wrap around or enter plant roots. The fungus supplies the plant with water and nutrients such as phosphorus and nitrogen from the soil, and the plant pays with sugars made by photosynthesis. This partnership is ancient and widespread, and it is not in doubt.
Because a single fungus can connect to more than one tree, scientists proposed 'common mycorrhizal networks' linking whole forests. In 1997, Suzanne Simard and colleagues published research in Nature suggesting carbon could move between trees through such networks, and the journal's cover called it the 'wood-wide web'. Books and documentaries went further, describing 'mother trees' nurturing seedlings and warning neighbours of insect attack.
In 2023, Justine Karst, Melanie Jones and Jason Hoeksema published a review in Nature Ecology & Evolution examining the evidence behind three popular claims: that these networks are widespread in forests, that resources move through them to seedlings in ways that boost growth, and that mature trees preferentially help their offspring. They found the evidence for each was weak, inconsistent or open to other explanations, and that claims had drifted away from the data as they were cited.
This doesn't mean forests are not interconnected; fungi and roots form a genuinely complex underground world, and research continues. But the story is a good example of how an exciting idea can outrun its evidence. The honest answer is that the forest floor is fascinating, and still largely unknown.
Source: Karst, Jones & Hoeksema (2023), Nature Ecology & Evolution
