Do trees have a social network?

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Trees communicate to one another, just not through conventional means. Photo by Pixabay.

Peter Wohlleben is a renowned German forester and author of  “The Hidden Life of Trees: What They Feel, How They Communicate.”  He says that because trees cannot move, they use their roots to communicate, make decisions, and even store memories. They literally stand on their heads, as their “brains” lie in their roots. 

His new book, “The Heartbeat of Trees: Embracing Our Ancient Bond with Forests and Nature,” features the latest science and research on tree communication. But its message is simple: The age-old ties linking humans to the forest are alive and well — we just have to know where to look. KCRW’s Jonathan Bastian talks with Wohlleben about the hidden and surprising life of trees.  


Peter Wohlleben’s new book, “The Heartbeat of Trees: Embracing Our Ancient Bond with Forests and Nature,” features the latest science and research on tree communication. Photo by Miriam Wohlleben.

KCRW: Your earlier research describes trees as social creatures. Can you introduce us to this idea of how a tree can be social?

Peter Wohlleben: “I think it surprises many people. But on the other hand, it's a principle of nature that cooperation is better than competition. And trees are so much older than we are. And often we think that [I’m] antrophomorphsing trees, but it's the other way around. We have developed very much later than trees, and we have the same principles. 

So that means, for example, that trees know the forest. And trees are able to cool down the local climate around about 15 degrees by sweating together. For example, a big broadleaf tree is able to get out as much as 500 liters of water per day. And that's cooling the local climate, there's much more rain over such forests. And that all just works when trees work together as a forest, as a social community.”

You talk about how trees are able to nurse a sick neighbor—a tree that's not doing as well can be helped by others. Is that right?

“That's right. And I discovered that about 25 years ago, when I stumbled upon an old stump. The tree had been felled about 400 years ago, and was still alive without any green leaves. A tree burns sugar and cells. So it needs energy. It needs fresh sugar from photosynthesis, and without any green leaves, that's not possible. So how could this tree stump survive 400 years? The only explanation was that surrounding trees were feeding this tree, this stump. I'm always talking about a ‘tree’ because the real tree is underground, what we see above is just for getting nutrition. 

As a forester, I was trained to look at trees as competitors. And I was the referee. And when two trees were struggling, I could cut one tree down and say, ‘Okay, I'm the referee, and you now get more space. And in reality, it's the destruction of a social community. And with this old stump, I learned that the trees are cooperative.”

For them, what's the point of forming these communities?

“A tree wants to become very old, because the tree is very slow. And it takes decades, if not centuries, to become grown up, to reproduce. And there are many dangers. Therefore, they support each other. ... A tree’s childhood could last as long as 200 or 300 years. Then the tree, with this very slow youth growth, can become 1000 years old, up to 10,000 years old, even more. The oldest tree we know so far is around 10,000 years old. This is an old lonely spruce tree in Sweden in the mountains. But perhaps there are much older trees, because there has yet to be done a lot of research on the same trees.”

Is it too much of a stretch to say that a tree has a certain consciousness, in the way that we think of humans as conscious beings?

“That's a difficult question, because no scientist, no biologist would say yes. We have scientists here in Germany who say, ‘For that question, we have to ask plants.’ But there are some hints that there is consciousness. For example, we know that trees produce pain suppressing substances. Pain is just a reflex. When a tree is hurt by a bark beetle, then we can measure an electrical signal going through the tissue. And there's a reaction on this attack. But that could be just a reflex. We produce pain suppressing substances in situations of stress, for example, when we have an accident. … Why? To stay conscious, and trees and plants are doing the same. 

So if a being produces pain suppressing substances, then we can assume that there is a sort of consciousness. But people say, ‘Oh, no, all of that, that's going too far.’ And the reason why we react like this is, what else should we eat? But these questions are not scientific questions. It's okay to eat plants. It's okay to eat meat, although I'm a vegetarian, because t meat is the main forest killer. But if plants are conscious about what they are doing, it's okay to eat them. Because otherwise we will die. And it's our right to survive.”

Can you talk about the role of trees in climate change at large, both in terms of removing them, and the importance of keeping them to just have some semblance of balance on the planet?

“Most governments regard trees, the burning of wood, as carbon neutral. And that's very bad, because most scientists say that burning wood is worse than burning coal. But it's regarded to be carbon neutral, and therefore more and more power plants are changing from coal to wood. That's a bad development. For example, there's much wood from the south eastern United States burnt in European power plants. 

But in terms of climate change, trees are the best ‘machines’ to take up carbon dioxide. Trees can cool down the landscape. Trees can create more rain. ... Therefore, we need more forest and we need more old trees. Most of the trees are too young. It’s just old trees that are able to do all those benefits. And perhaps we would say, ‘Ah, but it takes decades to let new forests grow.’ Yeah, but let's start now with new forests and let's reduce forestry. I wouldn't say we shouldn't have forestry. But we should have less timber consumption, should have less stressed forests, and we should have more protected forests. Because they have so many benefits.”

What about the importance of bringing children into forests and these nature rich experiences?

“I think it's very important to bring children into forests, and bring them in the right way. What's always cool with children is when it's an adventure for them. So not a lesson or doctrine, not trying to teach children anything, but let them experience nature. And we do that a lot. For example, we let them shout very loud. Most people say, ‘Ah, you have to be very silent so not to disturb the animals.’ But the animals are relaxing when children are loud. Why? Because then they know ‘Ah, these people are not hunters.’ And animals just fear hunters. Otherwise, we can come very close to them. And so children, who are told to be silent, don't like forests.”

What do forests tell us, metaphorically, about life or who we are?

“I think the trees tell us a lot. Because trees are not competing, they're cooperating ... it's a wonderful network of life. Of course, we have also sad things. We have trees broken down by storms, or killed by fires, or insects, or whatever. But life is always coming back. And we know that trees are passing their experiences to the new generation by epigenetic effects. And they're learning very fast, but they are sharing, sharing, sharing, without expecting to get anything back. And I think sharing, without conditions, is one of the best things we could have in our society.”

You write a lot about new approaches to how to manage forests. What would you say about what's coming next, or new practices you hope to spread across the globe? 

“I would say we need more letting nature do the job. For example, if you plant the forest, it can never be as good as a forest which came by nature, because when you plant a tree, you damage the root system, and the root system is the brain of a tree. And we know that this damage will never heal the whole lifetime of the tree. So it gets more unstable or it will die earlier, and so on. So it's always better to let the forest come back itself. … You can harvest timber in such a forest in [several] decades or even centuries, but more carefully and with more respect, and perhaps without those big machines that are destroying the soil, which is even more important, because it stores water like a sponge for dry summers. I would wish for a forestry that is more respectful.”

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Andrea Brody