The Hidden Life of Trees: What They Feel, How They Communicate: Discoveries from a Secret World
Peter Wohlleben, 2015
How did a stump without a single leaf live for several centuries, and why does a giraffe eat acacia while walking into the wind? For many years the forester Peter Wohlleben saw nothing in trees but timber, until he came to see the forest as a community. In his book, trees share sugar, warn each other of danger and slowly raise their children in the shade. After it, an ordinary walk in the forest will feel completely different.
Who it is for
For anyone who loves walking in the forest and wants to understand what goes on there. And for anyone who plants trees in a garden, a yard or at a country house.
If you hear a soft clicking on your next walk in the forest, then maybe it isn't only the wind…
The stones that turned out to be a tree
A forester was walking through an old beech forest when he noticed some strange stones covered in moss. They were curved, with hollows, and lay in a circle about a meter and a half across. He lifted the moss and saw bark underneath. These weren't stones but the remains of a huge stump. The tree had been cut down 400 to 500 years ago at the latest. The forester scraped the bark with his pocketknife and saw a green layer. The stump was alive.
The forester's name is Peter Wohlleben, and for many years he has worked in the forest of the German village of Hümmel. At first, he says, he knew about as much about the lives of trees as a butcher knows about the feelings of animals. Every day he judged hundreds of trunks by one thing only: how much their timber was worth. His view changed when he started taking tourists through the forest. The crooked, gnarled trees he had thought worthless filled his visitors with delight.
How did the stump live for so many centuries? It has no leaves, and without leaves photosynthesis is impossible. That's the name for the way a plant makes its own food: it turns light, water and air into sugar. Wohlleben's answer: the neighbors fed the stump. The beeches around it passed it a sugar solution through their roots. This discovery grew into the book's main idea: a forest isn't a lumberyard but a community where trees take care of each other.
Wohlleben talks about trees as if they were people: they have friends, mothers, a school and street kids. Scientists often argue with him, and at the end we'll tell you what about. But first, let's look underground, where trees hold on to each other.
A tree is as strong as its forest
Garden owners often ask Wohlleben whether their trees are standing too close together. They think the neighbors are taking light and water from each other. Forestry reasons the same way. Every few years foresters cut down some of the trunks so the rest have more room and thicken faster.
For trees of different species, this is true: they really do compete for light and water. But with trees of the same species, the author argues, things are different. Vanessa Bursche from the German city of Aachen studied undisturbed beech forests. The soil in them varies from place to place: stony in one spot, rich and moist in another. And yet every beech, thick or thin, produced the same amount of sugar per leaf. Apparently, the trees were sharing sugar underground, through their roots. Those with plenty give, and the hungry ones get help. Scientists from the city of Lübeck found something else: a beech forest where the trees stand close together grows more than a thinned-out one.
Why would a tree feed its neighbor? A single tree does not make a forest. When a neighbor dies, a hole opens in the canopy. Wind rushes in, and the summer heat reaches the ground and dries it out. The closed canopy keeps the cool and the moisture inside, the way a roof keeps the warmth in a house. That's why even a strong tree needs its weak neighbor: a strong tree sometimes gets sick too, and then it waits for help itself.
The author learned this from his own mistake. In his first years on the job, he ordered the girdling of several young beeches, that is, cutting a ring of bark around the trunk so the trees would wither and die. Without bark, the sugar from the leaves can't reach the roots, and the roots starve to death. But some of the beeches survived and are still alive today. Wohlleben believes their roots were getting food from healthy neighbors. He still feels a little ashamed when he sees those trees.
This kind of help, the author observes, happens mainly in natural forests. Look up in an old beech forest. An ordinary tree stretches its branches in every direction until it runs into a neighbor. But two tree friends don't grow thick branches toward each other and spread their crowns outward instead. Sometimes such pairs even die together.
About the author
Peter Wohlleben is a German forester from the village of Hümmel in the Eifel mountains. "The Hidden Life of Trees" became a bestseller in Germany and has been translated into many languages.
All books by this author: Peter Wohlleben
Terms from the book
- Göttingen
- Photosynthesis: The way a plant makes its own food: in green leaves, light, water and carbon dioxide turn into sugar, and oxygen goes out into the air.
- Hümmel: A small village in the Eifel mountains in western Germany. Its community owns the forest where Peter Wohlleben has worked for many years.
- Bursche: Vanessa Bursche, a researcher at RWTH Aachen University. She studied how much sugar beeches produce in undisturbed beech forests.
- Aachen: A city in western Germany. Scientists and students from its technical university carried out research in Wohlleben's forest for many years.
- Lübeck: A city in northern Germany. It is home to the researchers who compared the growth of dense and thinned-out beech forests.
- Girdling: Cutting the bark off a tree in a ring around the trunk. Foresters do this to make a tree die standing, without felling it.
- Ethylene: A simple gas that plants give off. According to the book, an acacia that is being eaten releases it into the air and so warns the acacias nearby of danger.
- Hyphae: The very fine threads that make up the body of a fungus. Underground they weave into a dense network called mycelium.
- Mycorrhiza: A partnership between a fungus and a plant's roots. The fungal threads wrap around the root tips and grow into them: the fungus helps the tree get water and nutrients, and in return it gets sugar.
- Bonsai: The Japanese art of growing dwarf trees in a pot. The name is also used for such a little tree itself, with its low, flat crown.
- Giant sequoias: Huge conifers from the west coast of North America. There they easily grow twice as tall as 50 meters, a height that not one tree in a European park has yet passed.
- Bochum: A city in western Germany. Its Ruhr University carried out a large study on why tree roots grow into sewer pipes.
- Humus: The dark, fertile layer of soil. It forms from the remains of plants and animals that fungi, bacteria and tiny soil animals have broken down.
All terms
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