We all know that being outside in nature is good for us. A walk somewhere green clears your head, and a few days in the countryside tends to send people home in much better shape than they arrived.
What we know far less about is what is actually going on in a forest while we are walking through it. Forests are stranger and busier places than they look from the footpath, and a lot of what happens in them has only been worked out in the last few decades.
One commonly heard claim is that trees talk to each other, sending messages through the soil, passing food around, keeping an eye on their own seedlings.
So do they? The answer isn’t a straight yes or no, but what is super interesting is how the trees and nature can also talk to us in a way.
Do trees talk to each other?
Underneath a forest there is usually a layer of fungus wrapped around the tree roots. The fungus takes sugar from the tree and gives back water and nutrients that the roots would struggle to get on their own. That part is old, well established science. Nobody disputes it.
The interesting claim came later. In the nineties the Canadian forest ecologist Suzanne Simard ran experiments in British Columbia showing carbon moving between birch and fir trees through those fungal connections. Someone called it the wood wide web, and the story grew from there. Big old mother trees feeding seedlings. Trees sending chemical warnings to their neighbours when insects showed up. A forest as one cooperative thing looking after itself.
Then in 2023 three mycologists went back and checked. Justine Karst, Melanie Jones and Jason Hoeksema reviewed 26 field studies on fungal networks in forests, and then looked at how recent papers had been describing them. Fewer than half the statements being made about that original research held up. Only 18% of the field experiments showed network effects strong enough to matter once you account for the fact that trees also compete with each other underground. The warning signals and the mother trees feeding their own seedlings were the shakiest claims of the lot.
So the fungi are real, the connections are real, and things move along them. What is in question is the intention. A tree might be sharing with its neighbour. Or the fungus might be running its own business, taking what it needs and shifting the rest around, and the trees are along for the ride.
Here is something that complicates the cooperation story further. Look up in certain woods and you will see gaps between the canopies, channels of sky running between crowns that never quite touch. It is called crown shyness. Lodgepole pine does it. Japanese larch does it. Nobody is certain why. It might be wind knocking the branch tips against each other until they stop growing, or the trees sensing light bouncing off their neighbours and pulling up short. Either way, plenty of trees spend their whole lives keeping a polite distance.