The Hidden Life of Trees by Peter Wohlleben -- a review by Susan Price

 

The Hidden Life of Trees

I think this book has blown my mind.

I'll give you a quote. Wohlleben is discussing coppiced trees: that is, trees that have been felled, or partially felled, so new trunks sprout from the root. It was commonly done in the past to trees such as hazel and yew, to 'farm' trees by producing a continuous growth of new wood.

But how to measure the age of these coppiced trees? Are they as old as the new growth? In which case, they're just a few years old, since coppicing is done roughly every eight to ten years.

Or, are these coppiced trees as old as the roots they re-grow from? In which case, they may be hundreds of years old.

Peter Wohlleben tells us that scientists investigated this question by:

'...researching ancient spruce in Dalarna province in Sweden. The oldest spruce in Dalarna has grown a carpet of flat shrubby growth around its single small trunk. All this growth belongs to one tree, and its roots were tested using carbon 14 dating... [This] revealed the spruce to be an absolutely unbelievable 9,550 years old. The individual shoots were younger, but these new growths from the past few centuries were not considered to be stand-alone trees but part of a bigger whole... After all, it is the root that looks after the survival of an organism. It is the root that has withstood severe changes in climatic conditions. And it is the root that has regrown trunks time and time again. It is in the roots that centuries of experience are stored, and it is this experience that has allowed the tree's survival to the present day. As a result of this research on the spruce, a number of scientific schools of thought have been thrown overboard. On the one hand, before this research, no one had any idea that spruce could live for much more than five hundred years; on the other, until then, people have assumed that this conifer first arrived in Sweden two thousand years ago... For me, this inconspicuous small plant is a symbol for how little we understand about forests and trees and how many wonders we have yet to discover.'

Nearly ten thousand years old.

This tree is known as 'Old Tjikko' and has-- as you'd expect-- it's own Wikipedia page. I'm surprised it isn't influencing people on Instagram and Tik-Tok. But I daresay it feels it has better things to do.

(It was given its name by the scientists who discovered it, Lisa Öberg and her husband, Leif Kullman. They called it  after their old dog.) 

The wikipedia page explains that Tjikko is a clonal tree. That is, when its branches touch the ground -- because of being weighed down by snow, perhaps-- they take root. When one trunk dies, these younger 'cloned' trunks may survive. The tree as it's seen today stands 5 metres (16 feet) tall and is 'relatively young.' These under-achieving trunks may only live for 600 years. Weaklings.

But the root system is nine and a half thousand years old. The ice-sheets only retreated from this area about ten thousand years ago. The spruce was right in there, no messin'!

Wikipedia

Old Tjikko is estimated to have first sprouted around 7550 BC. Writing wasn't invented until 4000 BC. When some unknown person used a stylus to make these impressions in clay tablets, the Dalarna spruce was already three and a half thousand years old. And it's still going strong. Which makes my brain boggle half-way out my skull.

Further research has found that Old Tjikko has mates: there are about 20 spruce trees in the same area that are over 8000 years old.

 

For me, this passage about Old Tjikko was worth the price of the book -- but there is much more.

You may have heard of the Wood Wide Web-- this is the network of mycorrhizal fungi which wraps itself around the roots of trees and connects tree to tree over miles. The fungi strikes a good bargain with the tree: it enables the tree to draw in more water and nutrients that it would otherwise be able to do and, in return, claims a share of the goodies for itself. It also seems to help the trees communicate with each other.

Which they can do without fungal help. Researchers in Africa found that, when giraffes took a nibble at acacia trees, the trees pumped bitter, toxic substances into their leaves. The giraffes moved on-- but not to the next tree. Researchers noted that the giraffes either by-passed the nearer trees for ones at a distance, or they moved upwind.

Because the acacias were not only pumping their leaves full of poison, they were releasing ethylene, which was picked up by neighbouring trees, who began pumping their own leaves full of poison. But because trees are such laid-back life-forms, this took a little time and the canny giraffes knew that trees upwind wouldn't get the message, and those at a distance wouldn't have recieved it yet.

This doesn't just happen with acacias in Africa. In Northern Europe, our beeches, spruce and oaks have their own tricks. When a caterpillar chomps down on a leaf, the leaf's tissue sends electrical signals to the tree-- just as the tissue of our toes sends electrical signals to our brain when we stub them.

Our brain sends a signal back almost instantly, with the instruction, 'Go, "Ow!"' I'm not sure where a tree's brain is, and the response is much slower. It takes an hour, but the tree's response is to pump the leaves full of nasty, toxic chemicals.

Ichneumon wasp, Oxfordshire. Photo: C Sharp

But the trees are smarter than that. They can also identify which pest is attacking them, from their saliva. The tree then calls in Special Services. It releases pheromones which attract the predatory insects which most like to prey on the very pest that is attacking the tree. It might, for instance, call in an ichneumon wasp, which paralyses caterpillars with its sting, lays its eggs inside them and leaves the still living caterpillar to be eaten alive from the inside out by the wasp larvae. Moral: Do not mess with an elm tree. Their sense of revenge is positively Jacobean.

I suppose having this air-borne pheromone messaging and the root to root web is a bit like us having both email and phone.

Trees learn and they remember: they learn, for instance, how to hoard water during a drought and they never forget. Trees create their own eco-system and maintain it. It is cooler and moister in a forest than in unforested land, and it rains more often.

Trees form social communities and send food along their Wood Wide Web to nourish ailing, young or elderly trees. They will nourish even trees of a different species because all trees, together, create and preserve the conditions needed for the forest, whether they're of the trees' own kind or not. (Although beech trees tend to be a bit snobbish.)

Mother trees tenderly cherish their off-spring and the off-spring look after ancestors. In the first chapter, 'Friendships', Wohlleben describes how he discovered  'a patch of strange-looking mossy stones in one of the preserves of old beech trees that grows in the forest I manage.' Puzzled, he examined these 'stones' closely and discovered that they were wood.

This puzzled him even more, because beech wood usually decomposes quickly. He tried to lift the wooden stones and found they were attached to the ground. Digging down, he discovered a green layer-- which means chlorophyll, which meant these wooden 'pebbles' were alive. Because only living plants make chlorophyll.

Looking around, he saw that the 'stones' were arranged in a circle of about 1-5 meters (five feet) in diameter. He had found the stump of a tree that must have been felled four or five hundred years previously, because the interior had completely rotted away. How were these 'stones'-- the outer rim of an ancient tree-- still producing chlorophyll and still alive?

The answer, as scientists have discovered, is that the younger beeches surrounding it, and descended from it, were pumping nutrients to it and taking good care of this ancient founder of their community. And, who knows, maybe learning from it?

So it seems that trees have a strong welfare state -- and more social conscience and greater humanity than the Tory Party. Which, somehow, doesn't surprise me.

All in all, a wonderful, fascinating book. Every chapter, almost every page, makes you want to go, "Wow!" and find somebody to tell all about it. So my relatives are lucky that I can write this for Authors Electric.

After reading about the incredible age trees can reach, I can't resist quoting Terry Pratchett, who is probably my favourite writer. In his book, Reaper Man, he introduces us to the 'Counting Pines.' Being 'dimly aware' that humans count the rings of trees to calculate their age, the pines conclude that this is why humans cut trees down.

So, to make tree-felling unnecessary, the pines evolve to display their age, in numbers, at about eye-level on their trunks.

Within a year they were felled almost into extinction by the ornamental house number plate industry, and only a very few survive in hard-to-reach areas.

Pratchett allows us to listen to a conversation between a stand of these remote, rare trees.

The six Counting Pines in this clump were listening to the oldest, whose gnarled trunk declared it to be thirty-one thousand, seven hundred and thirty-four years old. The conversation took seventeen years, but has been speeded up. 

'I remember when all this wasn't fields.' The pines stared out over a thousand miles of landscape. The sky flickered like a bad special effect from a time travel movie. Snow appeared, stayed for an instant, and melted. 

'What was it, then?' said the nearest pine.

'Ice. If you can call it ice. We had proper glaciers in those days. Not like the ice you get now, here one season and gone the next. It hung around for ages.' 

'What happened to it, then?' 

'It went.' 

'Went where?' 

'Where things go. Everything's always rushing off.' 

'Wow. That was a sharp one.' 

'What was?' 

'That winter just then.' 

'Call that a winter? When I was a sapling we had winters -' 

Then the tree vanished. 

After a shocked pause for a couple of years, one of the clump said: 'He just went! Just like that! One day he was here, next he was gone!' 

If the other trees had been humans, they would have shuffled their feet. 

'It happens, lad,' said one of them, carefully. 

'He's been taken to a Better Place, you can be sure of that. He was a good tree.' 

The young tree, which was a mere five thousand, one hundred and eleven years old, said: 'What sort of Better Place?' 

'We're not sure, ' said one of the clump. It trembled uneasily in a week-long gale. 'But we think it involves . . . sawdust.' 

Since the trees were unable even to sense any event that took place in less than a day, they never heard the sound of axes.

 

 

The Hidden Life of Trees

 

 

 

 

 

 

  Susan Price's website can be found here.