Peter Wohlleben’s “The Hidden Life of Trees”

Until recently I was quite sure that a broad difference between animals and plants was that animals, because they are mobile, readily interact with each other (flocking, pursuing, etc.) while plants, anchored to the ground, don’t do so because they can’t. Except to attract insect pollinators, plants, I thought, live a life of exquisite solo struggle, seeking only the sun and water.

I’ve been steadily learning how far off I was. German forester Peter Wohlleben’s popular book, The Hidden Life of Trees: What They Feel, How They Communicate, is the most compelling lesson yet.

Among his many descriptions of communication and mutual assistance is Wohlleben’s account of how trees defend not only themselves but also each other. Observers have noted, for example, that umbrella thorn acacias in the African savannah pumped toxins into their leaves when they felt giraffes nibbling on them. “The giraffes got the message and moved on to other trees in the vicinity. But did they move on to trees close by? No, for the time being, they walked right by a few trees and resumed their meal only when they had moved about 100 yards away.” They passed by the nearest trees because the trees being nibbled, in addition to pumping a repellent, “gave off a warning gas that signaled to neighboring trees that a crisis was at hand.” The giraffes knew these trees would not taste any better and kept walking.

hidden life of trees (pri.org)

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Many trees also have the ability to call in the air force. Reacting to bites from hostile insects, such trees emit scents that attract predators that devour the pests. “For example, elms and pines call on small parasite wasps that lay their eggs inside leaf-eating caterpillars.” The growing larvae devour the caterpillars from the inside.

The book brims with information and appreciations of this kind. Three more examples:

  • Trees that spend their lives in the forest fare much better than trees raised in one place and then transplanted to the forest. “Because their roots are irreparably damaged,…they seem almost incapable of networking with one another.” Like “street kids,” they “behave like loners and suffer from their isolation.”
  • Time for trees is slow and long. Internally, they, like animals, send alerts to parts of their body via chemicals and electrical impulses. But in a tree the electrical impulses move only about a third of an inch per second. (In our bodies, pain signals move  through our nerves about two feet per second, muscle impulses a hundred times faster.) No wonder it seems to us that plants are unresponsive.
  • Conifers (evergreens) “keep all their green finery on their branches” throughout the winter and have been doing so for 270 million years. Then deciduous (leaf-bearing) trees came along 100 million years ago, growing and discarding annually millions of delicate green solar panels. Was this an improvement? Why go to all that trouble? Wohlleben asks. Because “By discarding their leaves, they avoid a critical force—winter storms.” Between high winds, muddy soil, and a surface area equivalent to that of a large sailboat, tall evergreens take a battering in European winters. Growing and then dropping their huge surface area every year proved well worth while for the leafy new comers.

Wohlleben’s liberal use of human descriptors to explain the actions of trees delights many readers and annoys others. Andrea Wulf, in her review of the book, has both reactions.

I’m usually not keen on anthropomorphizing nature—and here trees are “nursing their babies” and having “a long, leisurely breakfast in the sun” while…fungus mushrooms are “rascals” who steal sugar and nutrients. These cutesy expressions make me cringe….But I have to admit that Wohlleben pulls it off—most of the time—because he sticks with scientific research and has a knack for making complex biology simple and thoroughly enjoyable.

I agree. While the vocabulary may bestow on trees a dignity and affection that we usually reserve for our own kind, it is scientists’ growing understanding of trees that creates the real story here. At a time of rapid environmental change, the book is as fascinating a revelation as one could ask for that life is even more intricate and purposeful than we knew.

What the Trees Tell Us

The Trees

by Philip Larkin

The trees are coming into leaf
Like something almost being said;
The recent buds relax and spread,
Their greenness is a kind of grief.

Is it that they are born again
And we grow old? No, they die too,
Their yearly trick of looking new
Is written down in rings of grain.

Yet still the unresting castles thresh
In fullgrown thickness every May.
Last year is dead, they seem to say,
Begin afresh, afresh, afresh.

Hope Jahren’s ‘Lab Girl’ and the Dramatic Life of Plants

Much as people admire plants, it is difficult to relate to them. It takes a unusual focus to sympathize with a plant’s struggles, to identify with it, to understand its idiosyncrasies. We have an immense range of words and images for capturing our own inner experiences—fear, exhaustion, revulsion, joy, thirst and so forth—but a mere handful for even the most prominent stages of plant life—growing, blooming, wilting, and a few others. This distance isn’t surprising. Plants are different from us in the most basic ways. They are anchored to the ground, they don’t have faces, and they make their own food. We acknowledge them as members of the family of life, but they also seem alien.

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The poverty of our understanding of plants contributes, I believe, to our uneasiness about the meaning of our lives. We’re prone to feeling that being alive is either an exclusively human pleasure or a lonely human struggle. It’s easy to lose touch with the reality that plants along with animals have been passing through the experiences of growing, struggling, fending off threats, and sometimes flourishing, for hundreds of millions of years and by the billions. We might feel more at home in our own skins if our imaginations could take in the  lives of plants a little more readily.

Hope Jahren helps us do so. Lab Girl, her memoir, traces her life through the rigors of becoming an established research scientist and her workaholic triumphs and disappointments in labs and in the field. The bristling autobiographical chapters alternate with brief essays about how plants function and survive. It’s these plant chapters that most caught my attention. Here are excerpts:

      No risk is more terrifying than that taken by the first root. A lucky root will eventually find water, but its first job is to anchor—to anchor an embryo and forever end its mobile phases, however passive that mobility was. Once the first root is extended, the plant will never again enjoy any hope (however feeble) of relocating to a place less cold, less, dry, less dangerous. Indeed, it will face frost, drought, and greedy jaws without any possibility of flight. ….The root grows down before the shoot grows up, and so there is no possibility for green tissue to make new food for several days or even weeks. Rooting exhausts the very last reserves of the seed.  The gamble is everything, and losing means death. The odds are more than a million to one against success.
But when it wins, it wins big. If a root finds what it needs, it bulks into a taproot—an anchor that can swell and split bedrock, and move gallons of water daily for years.  (52)

     A cactus doesn’t live in the desert because it likes the desert; it lives there because the desert hasn’t killed it yet. Any plant you find growing in the desert will grow a lot better if you take it out of the desert. The desert is like a lot of lousy neighborhoods: nobody living there can afford to move…. A desert botanist is a rare scientist indeed and eventually becomes inured to the misery of her subjects. Personally, I don’t have the stomach to deal with such suffering day in and day out.   (142)

     Here’s my personal request to you: if you have any private land at all, plant one tree on it this year. If you’re renting a place with a yard, plant a tree in it and see if your landlord notices. If he does, insist to him that it was always there….
Once your baby tree is in the ground, check it daily, because the first three years are critical. Remember that you are your tree’s only friend in a hostile world. If you do own the land that it is planted on, create a savings account and put five dollars in it every month, so that when your tree gets sick between ages twenty and thirty (and it will), you can have a tree doctor over to cure it, instead of just cutting it down….
At the end of this exercise, you’ll have a tree and it will have you. You can measure it monthly and chart your own growth curve. Every day, you can look at your tree, watch what it does, and try to see the world from its perspective. Stretch your imagination until it hurts: what is your tree trying to do? What does it wish for? What does it care about? Make a guess. Say it out loud.    (282)

Jahren’s language seems at first to personify plants heavily and maybe excessively, but she’s careful. She parallels our own emotional experiences with similar situations that plants experience in whatever way they experience them. Putting down the first root really is an all-or-nothing risk even if the seed doesn’t go through the sleepless nights that we would. Desert plants really do “suffer” in that they function minimally in their near-lethal environment. In this way Jaren brings us closer to aspects of plants’ lives that we cannot easily think about. Most people are more inclined to imagine what it is like to live on the moon than what it must be like for the tree in the backyard to be bracing for winter. We can’t know for sure how a plant experiences events, but we can, as she urges us, “stretch [our] imagination until it hurts.”

And then there’s “you’ll have a tree and it will have you.” Considering the world’s deteriorating environment, Jahren argues, if one tree can rely on you, that tree is well off. I would add that the benefit is mutual; we ourselves are better off if we can share and feel, even faintly, the life of any plant.