Book Review: The Heartbeat of Trees

Virginia Naef reviews The Heartbeat of Trees: Embracing Our Ancient Bond with Forests and Nature by Peter Wohlleben, 2019

the heartbeat of trees

“Sometimes I feel we do not respect nature the way people used to do. There was a time when trees and nature in general played a much more important role in our lives.”

-Wohlleben

German ecologist Peter Wohlleben has spent much of his career peeling away from his classical training as a forester, wherein trees are merely commodities, and toward understanding trees as worthy members of a forest community.  A community that is interdependent and in continual communication with each member.

Here in his 6th book on the wondrousness of trees, Wohlleben gathers a wealth of disparate facts into a unifying theme. The theme of communication.  And communication can only occur through the senses.

Thus the book begins with a lengthy discussion of the senses that humans and trees and other life forms share.  There are seven of them.  For the first five: sight, sound, smell, taste, touch; Wohlleben demonstrates the commonalities between plants and animals, between humans and trees. Animals (us) have specialized organs to sense our surroundings, plants (trees) communicate chemically with their environment through their roots, stems and leaves.

“Within a species, trees in ancient forests share sugar solution through their roots and warn each other of danger by releasing scent messages and communicating through their root systems.”

The sixth and seventh senses are more esoteric. The sixth sense is the “other”. Sensations or premonitions that can’t be explained. Wohlleben gives the example of water buffalo fleeing to higher ground ahead of the devastating Indonesian tsunami of 2004. How did they know? And in humans:

“We’re talking about the sudden vague feeling people sometimes have that something is not right. The body sounds the alarm and, in the best case scenario, the person becomes consciously aware of the threat and manages to escape. The sensations can also be less dramatic, such as the feeling of being watched—you turn around and see that someone is indeed looking at you…”.

Do trees have a sixth sense? We have no evidence of it as yet.

The seventh sense, in Wohlleben’s accounting, is proprioception. Awareness of self and one’s position in relation to one’s environment. In animals it may be conscious or unconscious. An example would be a person’s ability to stand upright, a process that requires exquisite coordination of muscles and nerves, but of which we are only dimly aware. 

The book is replete in ways that trees and forests benefit people. A forest can be a medicine cabinet.  A feeling of well-being is experienced when walking through the forest.  Blood pressure is lowered. Cancer cells are suppressed.  And we have willows for aspirin.  Maple leaves for insect bites. Oak for sore throat. And although the author doesn’t mention it, yew for breast and other cancers.

The book is titled ” The Heartbeat of Trees”, but do trees really have a heartbeat? Yes they do, it’s just really slow. Transpiration (passive diffusion) alone cannot move enough water upward to the crown. Rather a subtle pumping action may be involved. Scientists have documented expansion and contraction of the tree’s trunk, on the order of 0.002 inches, and arriving at a “heartbeat” of one every three to four hours.

On page 140 Wohlleben admits to believing trees are sentient beings. Wherein he decries the painful brutality of logging. Wikipedia defines sentience as the capacity to experience feelings and sensations. Plants can “feel” things and make decisions. In concordance with the plant researcher Frantisek Baluska, Wohlleben proposes that plants can feel pain and react to it. Reactions include sending out alarm chemicals, movement away from the source of pain, and decisions to retard growth.

The latter part of the book skips about from topic to topic, but generally deals with the ecological value of forests.  It’s chockablock with interesting facts, for example:

  • forests filter up to 20,300 tons of dust per sq. kilometer
  • in Germany around 10,000 species of plants and animals are dependent on the cool, dark, damp conditions under giant trees
  • logging of a large parcel destroys hundreds of thousands of nesting birds
  • a single beech can transpire 130 gallons of water on a hot day, lowering the surrounding temperature by 1 degree Celsius
  • fallen trees in place sequester carbon for thousands of years
  • conversely, logging a forest exposes the forest floor to sunlight, thereby increasing the decay rate of fallen wood and releasing carbon

Wohlleben rightly declares that: “Primeval forests are our most powerful allies in the fight against climate change.” If the forests of the Northern hemisphere were increased, rather than decreasing as they are now, the carbon they sequester would cool the planet. It’s simple: forests are giant air conditioners. Step into a wood on a hot day and you will immediately notice how much cooler and moister the atmosphere is. All accomplished by the act of transpiration by thousands of trees.

In the last chapters Wohlleben detaIls visits to three endangered forests: the Great Bear Rainforest in British Columbia, the Bialowieza in Poland, the Hambach ( ‘Hambi’) Forest in Germany. All are unique, all are critically threatened. The Bialowieza, for example, is the last primeval forest in Europe and is being partially logged nonetheless under the aegis of uncaring governments.

Throughout the book you can feel Wohlleben’s passionate love for trees. He makes a strong case for them as important living, breathing beings, not just stalks of celery. Trees should first, be allowed to live and grow old, and second, allowed to be with their compatriots in large, intact forests. Only in this way can their contribution to humans and the earth be fully realized.

Aerial photo of Hrodna forest (Augustow forest)

He finishes with an eloquent statement:

“It is by no means too late to protect nature. We are much too tightly bound to it. With the protests in Hambi and in Bialowieza, with the school strikes to draw attention to climate change, and with citizen’s petitions against honeybee die-off, people have sown the seeds of hope across generations so that now a complete change of direction is being ushered in. A change that is taking place not in our minds but in our hearts.”


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Virginia Naef is a contributing writer for Whatcom Million Trees Project. She has worn many hats, from construction laborer to wildlife biologist to laboratory technologist. But her greatest love is conservation biology. She has completed field studies on dam mitigation and river restoration for the Washington Department of Fish & Wildlife, and hatchery mitigation and fish habitat relationships in the South Fork Nooksack for the Lummi Tribe. Her Master’s Thesis through Huxley College is on the susceptibility of forest avifauna to nest predation in varying Northwestern landscapes.

Although retired, Virginia stays very busy on her 15 acre farm in Acme, as well as participating on the Boards of the Deming Friends of the Library and the Northwest All-Breed Goat Club. By helping the Whatcom Million Trees Project, she looks forward to bringing more trees to our beautiful region and to protecting the ones that are already here.

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