The roots of most trees are wrapped in fungi that supply minerals and take sugars in return, and one fungus can be attached to several trees at once. Out of that grew a story about a forest where trees feed and warn one another. How much of it holds?
The physical connection is real and documented. What is far less settled is whether the transfer matters to the receiving tree, and who the arrangement benefits, the tree or the fungus. Selection at the level of the individual rewards whatever reproduces more, not whatever is generous.
The basic fact here is solid and not in dispute. The roots of most trees are wrapped in fungi that supply minerals and water and take sugars in return, and one fungus can be attached to several trees at once. The is real and the physical connection is documented.
From there the gap between finding and story opens. The popular version describes a forest where old trees feed seedlings, pass resources to an ailing neighbor and warn each other about pests, all over a shared network.
The critique does not claim the network is absent. It checks three links in the chain. Whether the amount arriving matters to the receiving tree or is negligible. Whether it traveled through the fungus rather than through the soil. And , the tree or the fungus attached to both and acting for itself.
A review of how the claim spread found doing the work: papers were increasingly cited for conclusions stronger than they had reached, and the caveats fell away along the chain. really does move between trees. Deliberate help is a different claim, and it has not been carried.
wat. Labeled carbon did move between trees through the fungi. What was never shown is that the tree is doing it deliberately.
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It bears directly on forestry and restoration. If the network is essential, selective logging does more than it appears to above ground.
How do we know?
Field studies fingerprinted the fungi genetically and tagged carbon with a radioactive tracer to follow it. Critical reviews then went back over how strong the evidence for cooperation actually is.
What is still unknown
This is a good example of a true finding growing into too large a story. The network exists; the claim that trees help each other on purpose is not supported to the same degree.
Learn something?
Where to next
How do sea otters save kelp forests without touching them?ecology
What is a glowing mushroom glowing for?fungi
What tells a soil fungus to start building a snare?fungi