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Sentient beings

Did you know trees can taste, touch, hear, smell, memorise and communicate, just like animals?

By Aditya Misra
Published: Sunday 18 June 2017

Umbrella thorn acacias of the African
savannah pump toxic substances into their
leaves when animals nibble on them. They
even release ethylene to warn other trees
of the same species about the danger (THINKSTOCK PHOTO)

FANTASY MOVIES and fables that talked of “speaking trees” and “forest spirit” were not so off the mark after all. Backed with scientific evidence, The Hidden Life of Trees says that not only can trees communicate, they can also think and have memories.

As promised in the foreword, the book takes one to what appears a wonderland. Forest is a “superorganism” where trees communicate and exchange resources through roots and fungi networks. Just like an organism, they help each other in times of need or to warn of a crisis. The tree trunk, for instance, vibrates to “scream” to alert its neighbours to a water shortage.

Trees can also taste, touch, smell, hear and feel. And they exhibit these characteristics just the way animals do. The vibration of the tree trunk is effected with the help of water molecules, just like animals use water molecules to vibrate their vocal chords. And how do we know they can hear? The author, Peter Wohlleben, cites an experiment where roots of grain seedlings moved in the direction of the ultrasonic sound waves coming from the crackling of roots of other seedlings in the vicinity. The proof that they can taste comes from the way their defence mechanism is triggered. When nibbled on by an insect, the leaf “tastes” the insect’s saliva to release pheromones that attracts predators feeding on that insect. Leaves of beeches, spruce and oaks feel pain when they are chewed on and send electrical impulses, just like animals. Experiments on mimosas—plants that fold their leaves when touched—showed that they could “learn” that water droplets are harmless and stop folding to their touch. They could even “remember” and exhibited the same behaviour when the experiment was repeated weeks later.

These are fascinating facts—almost too bizarre to be true—because most of us have grown up believing that while trees do have life, they are not social and do not communicate. These concepts are incorporeal when it comes to the plant kingdom. Communication, for instance, cannot happen unless there is an idea, a brain to process that idea and a language to convey it. It also requires the judgement to decide that the idea needs to be conveyed. The physiology of a tree, as we know it, excludes these concepts, as we know them. It blurs the distinction between the two biggest categories of life on earth—the animal kingdom and the plant kingdom—because brain and communication are exclusively the domain of the animal kingdom.


Peter Wohlleben
Penguin Random House India <br />
 Rs 499 | 320 pages

Trees, the author says, are social beings and, depending on their neighbours and surroundings, they can be happy or sad and lonely. Isolated trees are “deaf and dumb”, having lost their ability to communic ate, and have a shorter lifespan. Trees in planted forests are loners and behave like “street kids” because their roots are irreparably damaged and incapable of networking. Some trees are even bullies, extracting more than their share of resources. But trees surrounded by their “tree parents”, live longer and are happier. Parent trees take care of their young ones. Even unrelated trees offer help, nursing their injured neighbours with nutrients. The author cites the example of a tree stump in Germany that has been kept alive by its neighbours for almost half-a-millennium.

So are trees intelligent beings? They do have brain-like structures at the root tips, says the author, which helps them decide what to do when they meet a rock or a toxic substance in their path. But the majority of plant researchers are sceptical about plants being a “repository of intelligence”.

“Among other things, they [plant researchers] get worked up about carrying over findings in similar situations with animals and, at the end of the day, about how this threatens to blur the boundary between plants and animals,” says the author. But blurring this boundary, he says, could be beneficial because it might make humans pay more attention to trees.

But why do trees socialise? Just like human communities, it is more advantageous for trees to work together. A lonely tree cannot create or maintain a consistent local climate. But together, trees can create a protected environment that shelters them from the wind and weather. “If every tree were looking out only for itself, then quite a few of them would never reach old age,” says Wohlleben. In fact, the affection with which he talks about trees and forest is quite remarkable. “When you know that trees experience pain and have memories and that tree parents live together with their children, then you can no longer just chop them down and disrupt their lives with large machines.”

So be careful before you thoughtlessly pluck a leaf or step on a shrub next time. The act won’t go unobserved. And the witnesses can communicate. Who knows, they might even know how to cast a spell.

`Trees are like elephants'
PETER WOHLLEBEN, a former forester in Germany, has authored several books on forests. Excerpts from an interview

How much of the tree language is yet to be deciphered? I think most of the tree language is unknown. It is like learning a language just by stepping on the feet of people around you and hearing what they call you then. We discovered what they communicate when they face insect attacks or droughts—that means we just know what they "talk" about when they are in danger. But we don't know what do they communicate if they feel comfortable or happy.

What are the differences, if any, that you see in the attitude towards trees in different countries/continents?

That was the biggest surprise for me and perhaps one of the explanations why a German book on trees is read all over the world. There are really no differences. Forests and trees belong to humankind since it exists; the only differences are the myths and tales about forests.

There is now a growing body of academic work that seeks to move beyond the human-centric view of nature. You also tend to follow the same idea and present stories from the perspective of trees. Was that a conscious choice?

I undertook guided tours in my forest for 25 years. The participants were my teachers. I instantly knew when my storytelling was boring. So I developed my stories around trees in the way that facts could be easily understood and that the participants developed a sympathy for trees. Afterwards, very often they would ask where to read more about trees—and that's how my books were born. They are written guided tours.

Environment protection is always posed in terms of how crucial it is to save trees to ensure human survival. Does this perspective need a rethink?

Yes, I think it is time for a new look on nature. Many of us are tired of the constant talk on how badly we treat our environment. I think there are two important things: one is that we should recognise that nature protection means first we protect ourselves. The other aspect is that we should enjoy nature more. What we love, we will protect. And that is my main aim: to show that trees are something like elephants. They live in family bands, they have emotions, they have memories, and they care for each other. The main difference is that they are so slow that they are regarded just a little more than stones. So I would like the readers to have more fun with trees and to discover hidden secrets of these "slowly" beings. Protection will follow automatically.

 This review was first published in the May 16-31, 2017 issue of Down To Earth magazine. 

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