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Facts or Fairy Tales? Peter Wohlleben and the Hidden Life of Trees

2018; Ecological Society of America; Volume: 99; Issue: 4 Linguagem: Inglês

10.1002/bes2.1443

2327-6096

Sharon Kingsland,

Forest Management and Policy

A review of Peter Wohlleben, The Hidden Life of Trees: What they Feel, How they Communicate—Discoveries from a Secret World, trans. Jane Billinghurst. Foreword by Tim Flannery. Greystone Books, Vancouver and Berkeley, 2016. In 2015, Peter Wohlleben, a German forester, published a popular book on the "hidden life of trees." The English version, titled The Hidden Life of Trees: What They Feel, How They Communicate—Discoveries from a Secret World, was published in 2016 and became a best-seller, but not without generating considerable controversy. Wohlleben began his career as a professional forester whose job was to assess the suitability of trees for harvesting. He abandoned this line of work two decades ago to organize survival training and log-cabin tours for tourists, and his interactions with his visitors altered his views of the forest, making him aware of the need to adopt a more ecologically sophisticated approach to forest management. Eventually, his community, the village of Hümmel in the Eifel mountains, hired him to manage their forest according to these ecological principles, which emphasize leaving the forest as undisturbed as possible, promoting diversity of species, and removing trees using animals rather than heavy machinery. Wohlleben's experiences opened his mind to the trees' "daily dramas and moving love stories," which he seeks to convey in this book. This sense of the hidden life of trees in turn forms the basis for what might be called a forest ethic, or the idea that trees be allowed to develop completely undisturbed by humans, so that they can live a full life in a way appropriate to their species. Plantation monocultures and the use of heavy machinery are the villains, and higher ecological standards for forest management are the goals. However, Wohlleben also hopes that management can be linked to preservation of undisturbed forests where trees are able to fulfill their "social needs," pass their knowledge on to the next generation, and grow "old with dignity." It is not entirely clear to whom this book is addressed, for it has infuriated professional forestry scientists while being warmly welcomed by lay people, who, Wohlleben admits, seem intuitively to grasp the need for an ecological approach to forest management better than forestry professionals do. The reason for this divided response is that his argument's force depends heavily on eliciting an emotional response from readers through its powers of suggestion. As Wohlleben concludes, if we understand the "capabilities" of plant life and learn to recognize trees' "emotional lives and needs," then we will also begin to treat plants differently, will cease to view forests as lumber factories, and will understand how forests can serve as oases of respite and recovery for us. His argument is intended to make us appreciate the benefits to us—as well as to the trees—of leaving the forests alone. The foreword to the English translation by Tim Flannery, himself a bestselling environmental writer, invites readers to enter a "magical place" where Wohlleben will reveal to us "trees with human faces, trees that can talk, and sometimes walk." Yet, it is Wohlleben's claim that his descriptions of tree behavior and his depictions of the complex social life of the forest rest on a foundation of science. The book's 76 endnotes point the reader toward many authoritative scientific publications as well as scientific news reports, mostly from the past decade, that appear to support the claim that he is simply conveying, in language accessible to the laymen, the factual findings of science. Why then did two German scientists launch an online petition in February 2017, calling on scientific colleagues to challenge these claims? The German title is "Auch im Wald: Fakten statt Märchen, Wissenschaft statt Wohlleben" ("Even in the forest, facts instead of fairy tales, science instead of Wohlleben"). In the English version, the petition's title is "Even in the forest, we want facts instead of fairy tales." The petition describes the book as a "conglomeration of half-truths, biased judgements, and wishful thinking" and argues that such oversimplified and emotional writing will help neither the environment in general nor forests in particular (English version of the petition available online).1 The petition has received just over 4,500 signatures and has provoked a discussion, more visible in the German and French media than in English language media, about how we represent scientific knowledge to the lay public. In English publications, critical reviews have been written by Erin Zimmerman, a plant biologist turned science writer, and Sarah Boon, also a former scientist and now science writer. These critical evaluations are exceptional. For the most part, the book has received enthusiastic reviews for revealing amazing "discoveries" and countless "wonders." These discoveries are not limited to the results of scientific research; Wohlleben also describes his own psychological and spiritual awakening over his many years of working in the forest. It is not so much what the science says, but what the science causes Wohlleben to think and imagine, which is the subject of this book. Perhaps because of the book's controversial reception in Europe, the English translation ends with an appreciative afterword by one of the scientists whose work is discussed, Suzanne Simard at the University of British Columbia. Since the early 1990s, she has studied the networks linking tree roots with mycorrhizal fungi, forming a web of underground relations that has been dubbed the "wood wide web." As she points out, there is a vast amount of research now being done worldwide on the ways trees communicate with each other above and below ground. The furor that surrounds the book stems from the quaint way in which Wohlleben describes tree communication and other aspects of forest ecology. This controversy raises many interesting questions about how we can motivate people to take steps that will protect and preserve our environment and our natural resources. On the surface, Wohlleben's book seems to be suggesting that we should look to science to discover ecological complexity and reasons to preserve that complexity. But paradoxically, the book indirectly suggests that plant science has been lacking, has been slow to develop, and can only be stimulated if we believe that plants are like animals, and hence like us. This book is an appeal to our emotions more than to our interest in how scientists make new ecological discoveries. Wohlleben's book steadfastly adopts a language that is completely devoid of any scientific jargon. His reason for doing so—that most scientific writing is incomprehensible to the public—is fair enough. One of his goals is to explain basic adaptations of trees that may not be familiar to most people, and to show the reader how, from an ecological standpoint, we need to view trees not as isolated individuals, but as communities bound up in a complex set of ecological relationships, with organisms of the same species, with organisms of different species, and most especially with the soil fungi that help to transmit nutrients to plant roots. In parts of the book, Wohlleben's description of these ecological relationships is uncontroversial. Drawing on scientific literature dealing with plant physiology and ecology, he unveils some of the remarkable adaptations of trees and their dependence on other species for nutrition and reproduction. His goal is to show that in natural forests that have been left undisturbed, there is high diversity of species, the environment is relatively stable, and the forest can persist for very long periods of time. To Wohlleben, this represents a "true" forest environment, in comparison with forests planted for lumber, where the full ecological community never develops and trees are harvested long before they reach their mature age. But to convey this difference between the planted forest and the natural forest, Wohlleben slips into language that is strongly anthropomorphic and teleological. Not only are trees like us in having an emotional and social life, but they seem capable of planning ahead to promote the optimum environment to guarantee their longevity. Trees do not just interact accidentally, but form "friendships" in natural forests, whereas in planted forests trees behave like "loners" that "suffer from their isolation." "Why are trees social beings?" he asks, answering "The reasons are the same as for human communities: there are advantages to working together." A group of silver-gray birches that nourish sick individuals reminds him of a herd of elephants: "Like the herd they, too, look after their own, and they help their sick and weak back up onto their feet. They are even reluctant to abandon their dead." Trees also possess "a secret language of scent" that Wohlleben compares to the way animals communicate using pheromones, or chemical messengers. Trees register "pain" when creatures nibble them, give off chemical "alarm calls", and as Dr. Simard found, they can also warn each other through chemical signals sent through the fungal networks around their root tips. The fungi act as "intermediaries to guarantee quick dissemination of news", operating like "fiber-optic internet cables" to transmit information and helping the trees exchange news about insects, drought, and other dangers. In a chapter on reproduction titled "Love", some trees "agree in advance" not to bloom every year, so that "herbivores cannot count on them." Beeches and oaks "take breaks" from blooming because they "fear" deer and wild boar, whereas conifers "don't need to worry" about taking breaks. In a chapter on "tree school," we are told that trees "learn" to become stable by reacting to the "painful" micro-tears that occur when they bend with the wind. This chapter illustrates particularly well how Wohlleben moves from reference to the scientific literature to imaginative conjecture about what trees are experiencing. When trees are really thirsty, he tells us, they begin to "scream," citing a study from the Swiss Federal Institute for Forest, Snow, and Landscape Research, which recorded ultrasonic vibrations in tree trunks when the flow of water from the roots to the leaves was interrupted. Wohlleben explains that the scientists viewed these sounds as "a purely mechanical event" that "probably doesn't mean anything." But he then raises the possibility that it does mean something, at least in his imagination: "When I think about the research results… it seems to me that these vibrations could indeed be much more than just vibrations—they could be cries of thirst. The trees might be screaming out a dire warning to their colleagues that water levels are running low." The debate that this anthropomorphic language has generated is reminiscent of an earlier controversy at the start of the 20th century, involving nature writers who in this case were writing about animal behavior in a way that made animals seem very like humans. Historian Ralph H. Lutts wrote about this controversy in his book, The Nature Fakers: Wildlife, Science and Sentiment, published in 1990. Readers of Wohlleben's book may be interested in Lutts's reflections on how this earlier controversy developed. The targets were popular nature writers such as Ernest Thompson Seton (who wrote under the nom-de-plume of Ernest Seton-Thompson) and especially William J. Long, a popular writer of animal stories who was also a Congregationalist minister. At issue was the question of whether these and other authors' descriptions of animal behaviors were accurate. Long, for instance, theorized that animals practiced a rude form of medicine by covering wounds with pine pitch, spruce resin, or clay. Seton-Thompson told a story about a fox who jumped on the back of a sheep, riding it for a few hundred yards, in order to throw pursuing dogs off its scent. These kinds of claims about the complexity or intentionality of animal behaviors drew criticism from John Burroughs, foremost American nature writer, who argued that animal behaviors were more instinctive. The controversy, which unfolded between 1903 and 1907, also drew in Burroughs' friend Theodore Roosevelt, then U.S. President, who was himself a naturalist. The question was whether these writers were reporting accurately on behaviors they had observed, or whether they were making things up—hence the accusation that they were "nature fakers." The controversy played out in newspapers and popular magazines, reached its height in 1907, and gradually died down, with Long as the main victim. Lutts views Long not as a fraud, but simply as someone in search of a new relationship with nature, one with emotional and ethical dimensions, but who was unequipped to use science to explore that new relationship. Wohlleben does purport to use science and to bring the hard evidence of scientific research in support of his arguments. But while he makes many valid points about how ecological relationships operate in the forest, his use of the scientific literature, as in the examples above, is often a springboard to an imagined conclusion that goes beyond the scientific facts. By the end, he invites us to tune into the trees' language when we go for a walk in the woods. If we experience health benefits and a sense of enjoyment while walking in an ancient forest, he imagines it is because there are fewer "alarm calls" compared with artificially planted trees, and therefore, the messages exchanged between trees are contented ones, through which we intuitively register the forest's health. Wohlleben does admit that plant researchers are skeptical about the idea that plant behavior suggests something akin to animal intelligence, the faculty of memory, or emotions. Biologists, in his words, get "worked up" about translating findings from animals to plants and blurring the boundaries between plants and animals. His response is "And so what? What would be so awful about that?" The distinction between plants and animals is an arbitrary one, in his view. He believes in the importance of erasing this distinction, because he thinks that recognizing the similarities would cause us to pay more attention to trees and other vegetation. The impression Wohlleben leaves is that plant science has been woefully neglected, an impression that is reinforced by the fact that his citations are quite recent and by his frequent reference to "discoveries," as though everything he describes has been discovered only in the past few years. Although he cannot be faulted for not writing a full history of plant science in a short popular book like this, this impression of science being stagnant or backward is seriously misleading. As Simard points out in her afterword, the amount of research on topics like tree communication is "vast." Some of the discoveries that Wohlleben describes, such as the ability of trees to register the length of day, go back a century and have been the subject of decades of intensive research. A century ago, plant physiologists would have been dismayed at the idea that comparing animals to plants would be a good way to stimulate interest in plants. They were trying to move beyond earlier tendencies to view plants as being like animals, precisely in order to stimulate more accurate scientific research on plants, research that would seek to understand plants on their own terms. Many of the past century's advances in plant physiology—the advances that are the basis of Wohlleben's book—were made by scientists who were dedicated to the idea that plants were different from animals. When Wohlleben does not acknowledge that long research tradition, and the long slow process by which scientific knowledge advances, he also obscures and trivializes the amount of effort and the level of long-term support from society that is required to advance scientific fields.