Peter Wohlleben
The hidden life of trees and the indestructible sleeping bag

Since 2015, this book has sold over a million copies in Germany alone and enjoyed bestseller status worldwide in over 40 languages; last year, it was adapted into a film. The German television channel SWR has given Wohlleben a star-studded TV series, Der mit dem Wald spricht (“The Tree Whisperer”), and he has become a popular guest on talk shows.

In our interview, Peter Wohlleben revealed to us more than just the hidden life of trees. He also explains why we humans will never be able to kill off nature, no matter how hard we try, and how a 22-year-old sleeping bag became his guardian angel.

Where do you think this sudden common interest in the forest and the success of your book The Hidden Life of Trees came from? If I remember correctly, you were shocked by how well it did.

I certainly was! There was little fanfare early on from the media, so we can’t say they were just riding a trend. Otherwise, they would have made more noise about it sooner. But people have a fundamentally deep connection to trees. We burn wood to cook, for instance, and our bodies relax when we’re near trees. Our blood pressure decreases noticeably. This phenomenon holds true worldwide.

So the Germans aren’t the forest romantics that they always claim to be?

No, they’re not. People across the globe are drawn to trees, even people from areas where there is hardly any forest, such as Israel or Iceland. Our German and Celtic ancestors alike even worshiped trees. To this day, Germany is home to some ofthe most remarkable specimens and wish trees in the world, some of which are pilgrimage sites, like the ancient oak trees of the Ivenacker Eichen park in Mecklenburg-Vorpommern. Both cultural and religious connections between humans and trees are a connecting thread throughout history, right up to today. And my book was still a surprise hit. Then it opened the floodgates for other books about the forest.

And other outdoor activities such as Japan’s shinrin-yoku – literally ‘forest bathing,’ a kind of nature therapy – are gaining followers by the day.

That’s right. And science has demonstrated the benefits of forest bathing.

And as a forester, you feel at home in the woods. But your books sharply criticize your own field of work, going so far as to compare it to factory farming. What connection do you see here?

Timber production isn’t supposed to prioritize public woods over nature protection and recovery; it’s supposed to by the other way round. The Federal Constitutional Court has decided as much with several laws. Yet foresters in Germany treat most of our forests like plantations. Thus, German forests are in bad condition and extremely sensitive to the effects of climate change.

Trees are actually late bloomers if you will. In their first years and even centuries, they are relatively small; they take their time growing and don’t reach their full height until they are old. But here, they are planted in rank and file, and usually, it’s spruce, pine, Douglas fir, larch, red oak, and chestnut, which aren’t native to many places in Germany. 

That’s not how you care for the forest. The trees are all the same age and come from nurseries where they are farmed and then harvested far too soon. On average, they get to about 78 years old. Compare that to most of our native tree species that can grow for 500 years or more. You can still find a few individuals, ancient trees in parks, for example. But the German forests with trees that are 500 or more years old are long gone.

What about the Black Forest, the Ore Mountains, or the Thuringian or Bavarian forests?

The Bavarian Forest is, in large parts, a plantation for softwood that we deliberately stopped cultivating. And now, 50 years later, it is growing into a natural forest again, which will take centuries more. But there are no more virgin forests to be found in Germany.

You’ve said immature trees straight out of the nursery are planted with trimmed roots, can’t anchor themselves as firmly in the soil, and are marked for a short life from day one. They grow faster and broader and are thus ‘slaughtered’ earlier.

Exactly. And you see the same thing in factory farming. In pig breeding, animals live six months instead of ten years. When you kill a tree that young, it doesn’t get a chance to learn. And yes, trees can learn!

How?

It’s been proven that, for example, the thousand-year-old oak trees of Ivenack learn. They change their genetic makeup through epigenetic processes and pass them on in their new form to their offspring. The speed of this change came across with the Ents in Lord of the Rings; they simply need time. Forests need time. But today’s forestry sector simply marches onto a plantation, chops down trees, and plants more in their place. And that’s exactly what’s holding us back.

So can trees like pine and spruce learn to adapt and survive in Germany even though they’re not native to this land? Or are they not quite there yet?

I love Nordic spruce forests! Yes, even trees adapt over time. These softwood trees are a Taiga species that generally find this climate much too warm and dry. They belong up in Sweden, Norway, Finland, and Russia, maybe in the Alps’ higher altitudes. Other than that, it’s like planting coconut trees here. You’d be disappointed every winter to see them freeze. It’s just a bad idea.

You say natural forests are super organisms, so what do we have here in Germany? Will our tree plantations simply exist as neighbors without ever growing together and becoming one?

We might think of it like the difference between a blooming meadow and a cornfield. Both are growing, but the cornfield looks rather clinical. The good news is that it can all come back if we just leave it alone and stop frantically planting trees. No one knows which trees work the best. Forests can even themselves out, but we have to step back and give them some peace to do that.

These days, we think only about how wood can be used, but far more important is what it does for the climate. Forests not only store up CO2 but in the summer, they can cool themselves by ten degrees. If it’s 40 degrees Celsius in a field, it will only be 30 degrees in an old, well-preserved forest because trees evaporate lots of water, leading to significantly more rain. A proper water cycle kicks into gear and ends up cooling the surrounding area, as well. This is a critical matter when it comes to climate change. But like I said, we first have to let the forest be and do as it will.

You’re a vocal opponent of clearing dead forests and have said we need only be patient because a deciduous forest will soon return all on its own. Why do we find it so hard to be patient? Is it because we can’t stand watching the decay? Or is it misplaced ambition? You’re not a psychologist, but you must have your own theories here.

I think it’s because humans are creatures of action. We want to accomplish things and be proud. We’re not good at letting things just be. We’d rather be active. Just look at modern politics: everyone wants to save the forest by doing something. People often ask: can’t they just plant trees with me? But that’s not the solution, at least not in Germany. If you want to have a forest, simply give an area some protection and provide it with space and time to work on its own. But people don’t like that because it doesn’t make a good story or emotional pictures. If you come back to the same area in 20 years, maybe compare it with Google Earth, then you’ll see and can document real changes – but not right away. However, most people expect to see the results fast when they’re doing some good, ideally in less than three weeks. Sadly, that’s not how nature works.

And the forestry sector demands a product. Wood and paper are valuable commodities in our world, from building to reading. How can we live our lives with a mind toward environmental friendliness?

Forest soil acts like a sponge. When heavy machinery like harvesters drive over it, they flatten the ground and literally suck the trees dry. And once that happens, the soil is never the same again. A forest floor that has been rolled over like this retains up to 95 percent less water than it did before. It can no longer absorb and save up the winter rainfall, and when trees have only the summer rain to live off, they’re really just living from hand to mouth, so to speak. They eventually stop growing. Collateral damage such as this makes machines much more expensive in the long term than horses would be. Horses could pull the wood out of the forest and to a location where machines can safely work. But that doesn’t sound very cutting-edge. Anything not involving technology seems old-fashioned. But really, it’s the other way round. 

Is wood too cheap?

Exactly. Wood is both a lovely and yet dirty raw material. A few days ago, a group of scientists from various disciplines published a petition saying wood is harmful to the climate. Wood sellers perpetuate the myth that wood is CO2-neutral, but it isn’t. That theory was disproven ten years ago. We have to use it more economically. We could impose a CO2 tax on wood or one that regulates demand. At the moment, the forestry sector produces as much wood as people consume, but here, again, we’re coming at it from the wrong angle. We should only be using wood to the extent that it doesn’t harm the ecosystem. And that would be a lot less.

In your book, you also explain that not all trees are alike. You urge us to think carefully about which trees we harvest and use up, based on the tree’s age and what other trees surround it. Trees, you add, are sensitive, social beings that communicate with one another and can even register pain when, say, parasites infest them. Are we supposed to take that literally?

Based on current research, like that conducted at the University of Bonn, in terms of plants, we can possibly take that literally. Of course, we may not want to hear it – first, animals have feelings, and now trees? And for many, empathy hardly extends to flies, let alone forests. But that’s science. We can actually measure plants’ ability to feel pain. When a beetle bores into the bark, an electric signal goes through the tree and triggers a chemical defense reaction. Now, this alone could just be a reflex, but in certain situations, plants even produce a pain-killing substance, just as humans when we’re in an accident but fight to remain conscious and retain our ability to make decisions. Plants don’t have neurons, but the chemical processes are in some respects identical to those in humans. From this, we can conclude that plants do, in fact, possess a kind of consciousness.

Let’s take that a step further: What does this mean for cut flowers, Christmas trees, and vegetables? Do we have to change our ways and eat only the fruit that falls from trees?

People tend to go straight to what they can’t do or can’t have: ‘If plants have feelings, am I not allowed to eat them?’ But when it comes to other things, we’re fairly reckless. Every animal needs nutrition from organic substances. We are no different. There’s no significant difference between, say, slicing a persimmon or slaughtering a pig from a purely biological standpoint. Well, I don’t eat meat anymore. Not just because of the animals but also because of the forest acreage that gets cleared to give animals more room to eat.

But what conclusion could we derive from all this? Would you change any part of the hierarchy of plants, animals, and humans?

The conclusion is that we should all be more careful in how we treat everything. We have to resolve to stop compromising other lifeforms where it isn’t absolutely necessary. And where it does prove necessary, to tread as lightly as possible. I’m talking about ecologically minded forestry and farming, keeping livestock in a manner that is compatible with their nature. We have to treat everything with more respect.

When we consume or take something, we should be able to enjoy it with a clear conscience, whether that’s another log we throw on the fire or the magazine we like to flip through. But advertisement inserts that no one asked for, discount furniture, or coal-fired power plants scheduled to be converted to burn wood pellets that are actually far more harmful to the environment – such madness can be avoided.

In one of your most moving sentiments, you insist that humans ultimately cannot destroy nature. That sounds too good to be true. But doesn’t that imply that we can continue acting as we always have with no concern for the cost?

It’s true. Humans cannot destroy nature. Indeed, not on a large scale. If we look 10 million, 100 million years down the road, what we do today really doesn’t matter. Most species alive today will have been replaced by millions of entirely new ones. Nature is change. Nothing is permanent. This is bad news for many species, especially our own, and that’s exactly the point. We are violently tearing apart our own ecological habitat. Individual species don’t return after they’ve died out; ecosystems do. But once we abuse our ecosystem past a certain point, then it’s too late. Humans are predators, and predators never can completely eradicate their prey. The population will starve long before the last bite is eaten. A pack of wolves, for example, could never wipe out all its quarry. It would starve first. The same would happen to us if we irreparably harm our habitat. We would go before it goes.

You’ve just written another children’s book, Kommst du mit nach draußen? (“Come Outside With Me”). How else have you made use of the lockdown, and what’s next for you?

Besides working on a new TV show, I’m writing another book for adults. In this one, I take a closer look at how trees learn, specifically how they’re responding to global warming. It’s a fascinating subject. I’m also producing a new podcast. I’m not traveling at all these days, which is very unusual for me, but the lockdown has given me the luxury of being able to finish off a few projects.

Although I do miss personal contact with people, especially meeting up for a chat over food or drinks. But my work has benefited from the pause in all the business-related hubbub. I really can’t complain.

Looking through our archives, we found the following photo of you sporting some Jack Wolfskin gear. Could you tell us the story of this picture?

That must have been about 20 years ago. In 1998, Jack Wolfskin and I worked together for the first time. I was trying to devise a way to save the Ancient Beech Forests of Germany. They had been condemned to be chopped down, so I told the local community I would offer survival training courses in those woods. No one thought that would make any difference. I asked Jack Wolfskin if they’d be interested in getting involved. They leaped at the chance, and the whole thing was a great success. By the way, I still have the sleeping bag from back then. It’s indestructible. I’ve taken it on at least 50 of these survival expeditions and used it at minus 16 degrees without an insulating mat. And it’s not even designed to withstand those conditions! Most recently, my son slept in it in the forest about two weeks ago.

You’re telling me that your son slept in the woods, in winter, with a 1998 Jack Wolfskin sleeping bag?

Yes! It still works perfectly.

Mr. Wohlleben, thank you very much for speaking with us.