THE way German forester Peter Wohlleben tells it, a key part of his journey began when he paused to look at an old stump. This was something he had passed many times while walking through the forest, but had always assumed was just a circle of moss covered stones. Then one day he bent down to take a look, and what he noticed was that under the moss was bark. He tried to lift the pieces of what he now thought were wood, and found they didn't budge. He took a knife, thinned back the bark and found underneath a green layer that indicated the wood was still alive. The entire centre of the 5ft span of this circle had rotted away.

The tree, he calculated, must have been felled 400-500 years earlier. “We saw that it is still alive,” he recalls, “this old stump and without any green leaves.”

That this stump was still living made him look differently on the forest. “It brings up questions,” he says. “That living stump must have been burning sugar for centuries without a green leaf. That means that it must get its energy from somewhere, and the solution was that the surrounding trees support this old stump through their root systems with sugar.” That stump still lives today. “It's like a tree that has retired,” he says, ever poetic.​​

This revelation chimed with how many experts now view trees. "Some scientists," Wohlleben observes. "now say that the real tree is underground, not above. It’s the roots system. The stem and the branches and the leaves are just the feeding organ of the tree, and the real tree and the brain like structures and so on are underground."​​

This is classic Wohlleben, talking about trees with a vocabulary that makes them seem quite human. With The Hidden Life Of Trees, he has probably done more to change how the world sees trees than any other author. His book became a global publishing sensation, communicating and popularising a growing new understanding of trees that was coming to light through scientific research – the work, for instance, of Professor Suzanne Simard of University of British Columbia. It articulated ideas that now increasingly inform how we look at forests – like the fact that trees, in a woodland, are linked to each other by a network of mycorrhizal fungi which carries messages and nutrients between them, a system some have called "the wood-wide web". He wrote of tree “friends” that supported each other, of families, and even of “mother” trees that “suckle their young”.​​

While Wohlleben’s writing was based on sound scientific research, it spoke with rich wonder, in a language that was relatable. This year he has published a follow-up, written for children, which tells many of the same stories in a still more accessible way, and is partly based on the kind of conversations he would have with children when he would take them out on tours as part of the forest academy he and his son run. The book, an ideal read for days indoors during this current epidemic, has a teasing title, Can You Hear The Trees Talking?

He laughs when I ask if he talks to trees. “You can talk to trees. But I don’t think trees can understand you.” Rather, he says the title is a variation on a question he would often ask children when he took them on guided tours through the woods: “Are trees able to talk?” ​​

To this, the children, he recalls, would often say, “No”. He would then reply, “Yes they can. But not with words like we do. With chemical words that are electro-signals like our internet. Trees are able to communicate in many different ways and scientists have found out hundreds of chemical words. For example trees are able to call predator for caterpillars which are feeding on their leaves’.”​​

We are talking, for this interview, with the help not of the wood-wide web, but of the world wide web. Wohlleben and I would have been meeting face to face, but instead, with our countries in coronavirus lockdown, he is sitting in his old forester house, surrounded by a large garden, host to 80 trees, which also backs onto a larger forest reserve in Germany’s Eifel region. Even over Skype, I get a sense of his immense warmth and humour. It travels down the line.​​

Wohlleben says he has plenty to do during this lockdown, though the forest academy he runs there has cancelled all guided tours and seminars. “I have work enough for the rest of the year because I’m writing the next children’s book and my own magazine.” He is also fortunate enough, in these difficult times, to hae easy access to forest and to the comforting company of trees. “The big advantage for me here is the trees are so close to my house. We have now a clear blue sky and the trees are just ready to bring out new leaves. When you go out, you can’t feel other than happy. We have all this bad news at the moment and that’s really hard to stand, therefore it’s really good to go out. Even if it’s just for ten minutes to take a deep breath and look at the trees and look at how social they are, how slow they are, how old they can get. You see that different things matter than just if the economy will increase by some per cent.” ​​

Among his favourite patch of forest is some “very old” beech woodland around 4km from his home. It's part of the forest he manages, in an environmentally friendly way, on behalf of the local municipality. “We have a project there,” he says, “where every person can be part of 4 euro rent of the forest for 50 years and therefore the forest is protected from tree cutting. It’s a very wonderful forest. And for me, when I go through this forest, I feel at peace because I know that nothing could happen to these trees and so I can relax and listen.”​​

The area Wohlleben looks after includes a burial wood, which is where he imagines his own remains will go in the end. “We set it up nearly 20 years ago. The first reason was to protect this old beech forest because otherwise it would have been felled. The community which owns it was able to get the money from selling the old beech trees as living tombstones. That was the start of this burial forest. It’s the best symbol for the circle of life – that we are part of nature and after that our body goes back to nature.”​

Even before he started to look more seriously at the science, Wohlleben, had a feeling that there was much more to trees than “being biorobots”. He recalls: “Then I read scientific papers and the University of Aachen made studies here in the forest. I talked to scientists and visited them during their research. For example at the university of Bonn there’s a professor researching whether trees can feel pain and he says they do. It’s more than just a reflex.”​​

Though Wohlleben does have favourite trees, he says, in general what he loves is "trees where they belong". "For example I love spruce trees in northern Sweden, or wonderful oak in Sherwood forest in England. I love every time I notice that trees feel well – and trees always feel well when they’re not in a plantation system.” ​​

Wohlleben spent 20 years working for the forestry commission on such plantations, which cover large swathes of Scotland. Now an intense critic of the plantation system, he thinks of that former job as being like a "tree butcher". ​

Among his concerns about plantations is that so often they involve the planting of non-natives. But also, he observes, that plantations don't operate like healthy communities of trees, helping each other. They are lonely trees, isolated yet in a crowd – not connected in the same way through roots and fungal networks. You don't, for instance, get a living stump such as the one he mentioned earlier in a plantation. "These stumps only," he says, "happen in unmanaged woodland. It’s like those plantation trees are lone wolves in a big crowd, because their root system is damaged. It looks like those trees aren’t able to connect properly any more.”​​

As a child, growing up in Germany’s former capital, Bonn, Wohlleben's fascination for nature began with animals. They were his first love, and he kept spiders in glasses and water turtles in an aquarium. "I hatched a chicken on the heating pillow of my grandma, because I read that if you talk with an egg, what hatched from it regards you as its mother – and it worked.”​​

I’m surprised to learn that he grew up in the city, in a third floor flat, as I imagined him as someone who had spent his childhood roaming feral in the forests. His father worked in the ministry of finance, his mother in the hospital. “I’ve always loved nature,” he says. “I have two sisters and one brother and they all do different things which have nothing to do with nature. I’m like the green sheep of the family.” ​​

On leaving school, he thought about doing a degree in biology, but then read in a newspaper that it was possible to study forestry. “I thought a forester was something like a tree-keeper. I only discovered it was more like a tree butcher afterwards. It was about big machines, clear felling, chemicals – like it is done all over the world.”​​

Later, when he began running survival training and log cabin tours for tourists, he began to look at the trees in his care in a new way, and began to fight the forestry commission approach. Even now he is still battling. One of the problems, he says, is that monocultural plantations continue to be cultivated in many countries, including our own. Recently, he wrote a letter to the German ministry of agriculture whose message was, he says, “We must stop this plantation system now because the tree plantations are mostly conifer plantations like spruce and pine and they’re dying now because of climate change.” Many of these trees, he says, are from the high north and suited to cooler temperatures. “But the old forest," he adds, "the old beech and oak forest, are stable and able to withstand the climate change.”​​

After many years fighting the forestry commission, Wohlleben decided that what he needed to do was, “talk to the forest owners, which, in Germany, because 52 percent belongs to communities or state, are often the people.” He began to write books. The first of these, he says, "were more pessimistic because I explained how the forest commissioners were working". But then he decided simply to explain, "how wonderful trees are", and began the breath-taking The Hidden Life Of Trees. ​​

Wohlleben has long been a keen storyteller, and recalls that when his children – two, now grown up – were little, he told them stories about nature before going to bed. "The stories were about two dwarves living in the forest and one was a little bit evil and one good. It was about greediness and nature destruction and how good it is to keep it intact. They were both living in an old tree stump and when the greedy one destroys nature then it affects also the good one. At last the good one always wins.” ​​

He is clearly a natural at communicating with children. I often thought when reading The Hidden Life Of Trees that the magic and storytelling he weaves around the science made it a perfect book for older kids. This current picture book asks alluring questions. Do some trees prefer to be alone? Are some trees brave? Do trees sweat in summer? Is there a forest internet? ​​

It also encourages a new lexicon for talking about trees, as well as a new way of thinking about our human relationships or even what it means to "think" or feel pain. Some might be uncomfortable with what they see as an anthropomorphic view on plant life, but Wohlleben doesn’t see it as that. “Trees are more than just biomachines. There is a big community of responsibility, co-operation, taking care of each other. And this co-operation is not just a human principle. It’s a principle of nature that’s perhaps as old as hundreds of millions of millions of years, and our species is just 300,000 years old. Some people say that’s a metaphor to compare the tree society with our society. No. It’s vice versa. We developed out of these societies.”​​

​Like many, he is worried about the climate crisis, and sees trees as having an important role in the solution. That’s not, he says, just because they absorb carbon dioxide but because they have a cooling effect. “New research shows that a big beech or oak forest is able to cool down on average summer times 15 degrees lower than a city. That means they create their own cool local climate and that’s a key thing in times of climate change”

But, planting trees, he says, is not enough. “We should massively reduce our CO2 emissions.”​​

The global reaction to the coronavirus crisis is giving him hope that the drastic measures needed to reduce emissions and limit our impact may be possible. “It’s very sad that we have this coronavirus,” he says, “but one of the good things that may turn out is that we think in a different way about nature, and not just about money. Everyone knows at the moment that it’s not just about money.

"I hope when it’s over, that we will remember this and be a little bit more gentle to nature. Because we are still part of nature, as everyone knows now. I do not want this crisis, but we have it now and we have to take it as it is. I think we can turn it into a good thing, afterwards, and that we will look more at climate change, look at our forest ecosystems. Trees are really a good indicator for how we treat nature.”​​

What we are learning about trees, he believes, should also lead us towards a different attitude towards how we use them, care for them and value the things we make from them. He describes this as a question of, "how do we treat a living being before using them?"

Reflecting on his own journey towards this appreciation of trees as beings, he says: "I’m now more the person I thought I would be after studying forestry. I’m a tree-keeper and not a tree-butcher. That took me more than 30 years. Perhaps I would have been better to have studied something else, so I would have made my way faster. I did it that hard way. Nowadays I’m a tree-keeper and that’s exactly what I wanted to be when I was six years old. I remember I said to my parents, I want to be an environmentalist.”​​

Can You Hear The Trees Talking? is published by Greystone Books