The Hidden Life of Trees: What They Feel, How They Communicate—Discoveries from a Secret World

by Peter Wohlleben

  In my garden, a single beech seems to prefer red leaves. It was planted by one of my predecessors, and it has grown into a large tree. I don’t like it very much because, in my opinion, the leaves look unhealthy. You can find trees with reddish leaves in many parks, where they are supposed to inject interest in an otherwise monotonous sea of green. The common English name for my tree is copper beech. (In German it is known as a Blutbuche, or “blood beech,” which doesn’t make me any more inclined to like it.) But really, I think I feel sorry for this tree because its deviation from the traditional appearance of a beech works to its disadvantage.

  The color is the result of a metabolic disorder. Young developing leaves on normal trees are often tinged red thanks to a kind of sun block in their delicate tissue. This is anthocyanin, which blocks ultraviolet rays to protect the little leaves. As the leaves grow, the anthocyanin is broken down with the help of an enzyme. A few beeches or maples deviate from the norm because they lack this enzyme. They cannot get rid of the red color, and they retain it even in their mature leaves. Therefore, their leaves strongly reflect red light and waste a considerable portion of the light’s energy. Of course, they still have the blue tones in the spectrum for photosynthesis, but they are not achieving the same levels of photosynthesis as their green-leaved relatives. These red trees keep appearing in Nature, but they never get established and always disappear again. Humans, however, love anything that is different, and so we seek out red varieties and propagate them. One man’s trash is another man’s treasure is one way to describe this behavior, which might stop if people knew more about the trees’ circumstances.

  The main reason we misunderstand trees, however, is that they are so incredibly slow. Their childhood and youth last ten times as long as ours. Their complete life-span is at least five times as long as ours. Active movements such as unfurling leaves or growing new shoots take weeks or even months. And so it seems to us that trees are static beings, only slightly more active than rocks. And the sounds that make the forest seem so alive—the rustling of the crowns in the wind, the creaking of branches and trunks as they blow back and forth—are only passive swaying motions that are, at best, a nuisance for the tree. It’s hardly any wonder that many people today see trees as nothing more than objects. At the same time, some of the processes under the trunk happen much more quickly than the ones we can see. For instance, water and nutrients—that is to say, “tree blood”—flow from the roots up to the leaves at the rate of a third of an inch per second.68

  Even conservationists and many foresters are victims of optical illusions in the forest. This is hardly surprising. People rely heavily on sight, and so we are particularly influenced by this sense. Thus, ancient forests in Central European latitudes often strike us as being dull and species poor when we see them for the first time. The diversity of animal life plays out mostly in the microscopic realm, hidden from the eyes of forest visitors. We notice only the larger species, such as birds or mammals, and we don’t see them very often because typical forest dwellers are mostly quiet and very shy. And so when I take people visiting my forest around the old beech preserves, they often ask why they hear so few birds. Species that live out in the open often make more noise and take less trouble to keep out of sight. Perhaps you are familiar with this behavior from your own garden, where tits and chickadees, blackbirds and robins quickly get used to you and don’t bother to hop or fly away more than a few yards when you come along. Even the butterflies in the forest are mostly brown and gray and blend in with bark when they land on a tree trunk, whereas those that fly in wide-open spaces vie with one another in such a symphony of color and iridescence that it’s almost impossible to miss them. It’s the same with the plants. Forest species are mostly small and look very much alike. There are so many hundreds of species of mosses, all tiny, that even I have lost track, and the same goes for the diversity of lichens. How much more attractive are the plants of the open plains. The radiant foxglove towering up to 6 feet tall, yellow ragwort, the sky-blue forget-me-not—such splendor brightens the hiker’s heart.

  It’s no wonder that some conservationists are thrilled when storms or commercial forestry operations disturb the forest ecosystem by opening up large clearings. They truly believe the open space increases species diversity, and they miss the fact that this is traumatic for the forest. In exchange for a few species adapted to open areas that now feel like a million dollars basking happily in the bright sun, hundreds of microscopic organisms of little interest to most people die out locally. A scientific study by the Ecological Society of Germany, Austria, and Switzerland concluded that although increased forest management leads to increased richness in the diversity of plant life, this is no cause for celebration but rather proof of the level of disturbance of the natural ecosystem.69

  35

  — SET FREE —

  IN THESE TIMES of dramatic environmental upheaval, our yearning for undisturbed nature is increasing. Countries around the world are enacting legislation to protect what remains of their original forests. In the United Kingdom, the designation “ancient woodlands” affords some protection to woodlands that have existed continuously since at least the 1600s. Often formerly the property of large estates, over their history they have been intensively managed for wood and wildlife, and so, although the wood itself may be ancient, the trees that grow there may not. In Australia, the term “old-growth forest” helps protect some ancient forests from logging, but as economic interests push back, arguments are inevitably raised about the precise meaning of the term.

  In the United States, forest preserves, such as the Adirondack and Catskill parks in New York State, keep economic interests out of the forests. According to the state constitution, the preserve “shall be forever kept as wild forest lands,” and the timber shall not be “sold, removed or destroyed.” In the wilderness areas of these preserves, most structures are not allowed, power vehicles are banned, and chainsaws require special permits. What started as a measure to ensure that excessive logging in the nineteenth century didn’t lead to soil erosion and silting up of the economically important Erie Canal has turned into a resource dedicated to the forest itself and visitors who “leave no trace” as they pass through.

  Even more remote is the Great Bear Rainforest in northern British Columbia, which covers almost 25,000 square miles along the rugged coast. Half of this area is forested, including about 8,900 square miles of old-growth trees. This primeval forest is home to the rare spirit bear, which although it is white, is not a polar bear but a black bear with white fur. First Nations in the area have been fighting since the 1990s to protect their homelands. On February 1, 2016, an agreement was announced to keep 85 percent of the forest unlogged, though it does allow for 15 percent of the trees, mostly old growth at low elevations, to be removed. After a long hard struggle, some progress, at least, has been made in protecting this very special place. Chief Marilyn Slett, president of Coastal First Nations, is well aware of the forest’s importance: “Our leaders understand our well being is connected to the well being of our lands and waters… If we use our knowledge and our wisdom to look after [them], they will look after us into the future.”70 The Kichwa of Sarayaku, Ecuador, see their forest as “the most exalted expression of life itself.”71

  In densely populated Central Europe, the forest is the last refuge for people who want to let their spirits soar in landscapes untouched by human hand. But there really isn’t any undisturbed nature left here. The old-growth forests disappeared centuries ago, first to the axes and finally under the plows of our forefathers, who were beset by famine. It’s true that today, once again, there are large tree-covered areas next to settlements and fields, but these are plantations rather than forests—the trees are all the same species and the same age. Politicians are beginning to debate whether such plantings can really be called forests at all.

  There’s consensus among German politicians that 5 percent of the forests should be left to their own devices so that th
ey can become the old-growth forests of tomorrow. At first, that doesn’t sound like much, and it’s downright embarrassing when compared with states in tropical parts of the world, the ones we always reproach for the lack of protection for their rain forests. But at least it’s a start. Even if only 2 percent of the forests in Germany were freed from human interference, that’s still more than 770 square miles. You could observe the free play of natural forces in such areas. In contrast to nature preserves, which are always carefully groomed, what would be preserved here would be doing absolutely nothing. In scientific terms, this is known as “process conservation.” And because Nature is completely uninterested in what we humans want, the processes don’t always progress as we would like them to.

  Basically, the more severely out of balance the protected area, the more intense the process of returning to undisturbed forest. The most extreme contrast would be a bare field, followed by a home lawn that is mowed every week. I notice this around our forest lodge, too. There are always oak, beech, and birch seedlings popping up in the grass. If I didn’t cut them off regularly, within five years I’d have a stand of young trees about 6 feet tall, and our little piece of paradise would disappear behind their foliage.

  In forested areas of Central Europe, it is the return of spruce and pine plantations to ancient forest that is most dramatic. And it is precisely these forests that are often part of newly established national parks, because people usually don’t want to consolidate them with the ecologically more valuable deciduous forests. It doesn’t really matter. The future old-growth forest is just as happy to develop from a monoculture. As long as people don’t meddle, the first drastic changes can be seen after just a few years. Usually, it’s the arrival of insects, such as tiny bark beetles, which can now proliferate and spread without hindrance. The conifers were originally planted in symmetrical rows in places that were too warm and dry for them. In these conditions, they are unable to defend themselves from their attackers, and within just a few weeks, their bark is completely dead as a result of the beetles’ depredations.

  The insect invasion spreads like wildfire through the former commercial forest, leaving in its wake a seemingly dead, barren landscape, strewn with the pale ribs of trees. This bleak scene makes the hearts of the resident sawmill workers bleed, as they would have preferred to put the trunks to good use. They also argue that the devastating sight means tourism can’t really get going either. That’s understandable if visitors come unprepared. They are expecting to take a walk in what is supposedly an intact forest, and instead of seeing healthy green growth, they encounter a series of hillsides completely covered in dead trees. In the Bavarian National Forest alone, more than 20 square miles of spruce forest have died since 1995—about one quarter of the total area of the park.72 Dead trunks are clearly more difficult for some visitors to bear than bald, empty spaces.

  Most national parks give in to the clamor of complaint and sell to sawmills the trees they have felled and removed from the forest to combat bark beetle infestations. This is a grave mistake. For the dead spruce and pines are midwives to the new deciduous forest. They store water in their dead trunks, which help cool the hot summer air to a bearable temperature. When they fall over, the impenetrable barricade of trunks acts as a natural fence through which no deer can pass. Protected in this way, the small oaks, bird cherries, and beeches can grow up unbrowsed. And when one day the dead conifers rot, they create valuable humus.

  But you don’t have an established forest yet, because the young trees don’t have any parents. There’s no one there to slow the growth of the little ones, to protect them, or in case of emergency, to feed them sugar. The first natural generation of trees in a national park, therefore, grows up more or less like the “street kids.” Even the mix of tree species is unnatural at first. The former coniferous plantation trees sow their seeds heavily before they depart, so spruce, pines, and Douglas firs grow along with the beeches, oaks, and silver firs. It’s at this point that officials usually get impatient. No question, if the conifers that have now fallen into disfavor were to be removed, the future old-growth forest would develop a bit more quickly. But once you understand that the first generation of trees is going to grow too quickly anyway and, therefore, is not going to get very old—and that the stable social structure of the forest is not going to be laid down until much later—then you can take a more relaxed view.

  The plantation trees growing in the mix will depart in less than a hundred years because they will grow above the tops of the deciduous trees and stand unprotected in the path of storms that will ruthlessly uproot them. These first gaps will be vanquished by the second generation of deciduous trees, which can now grow up protected by the leafy canopy formed by their parents. Even if these parents themselves don’t grow very old, they will still grow old enough to give their children a slow start. Once these youngsters reach the age of retirement, the future old-growth forest will have achieved equilibrium, and from then on, it will hardly change at all.

  It takes five hundred years from the time a national park is established to get to this point. Had large areas of an old deciduous forest that had seen only modest commercial use been put under protection, it would take only two hundred years to reach this stage. However, because all over Germany the forests chosen for protection are forests that are far from their natural state, you have to allow a little more time (from the trees’ point of view) and a particularly intense restructuring phase for the first few decades.

  There’s a common misconception about the appearance of old-growth forests in Europe, should they come to pass. Laypeople often assume that shrubby growth will take over the landscape and forests will become impenetrable. Where today the forests that predominate are at least partially accessible, tomorrow chaos will rule. Forest preserves untouched by foresters for more than a hundred years prove the opposite. Because of the deep shade, wild flowers and shrubs don’t have a chance, so the color brown (from old leaves) predominates on the natural forest floor. The small trees grow extremely slowly and very straight, and their side branches are short and narrow. The old mother trees dominate, and their flawless trunks stretch to the sky like the columns in a cathedral.

  In contrast to this, there is much more light in managed forests, because trees are constantly being removed. Grass and bushes grow in the gaps, and tangles of brambles prevent detours off the beaten path. When trees are felled and their crowns are left lying on the ground, the debris creates further obstacles. The whole forest presents a troubled and downright messy picture. Old-growth forests, however, are basically very accessible. There are just a few thick dead trunks lying on the ground here and there, which offer natural resting spots. Because the trees grow to be so old, few dead trees fall. Other than that, nothing much happens. Few changes are noticeable in a person’s lifetime. Preserves where managed forests are allowed to develop into old-growth forests have a calming effect on Nature and offer better experiences for people seeking rest and relaxation.

  And what about personal safety? Don’t we read every month about the dangers of walking out under old trees? Falling branches or complete trees that fall across footpaths, sheds, or parked cars? Certainly, that could happen. But the dangers of managed forests are much higher. More than 90 percent of storm damage happens to conifers growing in unstable plantations that fall over with wind gusts of 60 miles an hour. I don’t know of a single case where an old deciduous forest left to its own devices for many years has suffered comparable damage in similar weather. And so all I can say is: let’s have a bolder approach to wilderness!

  36

  — MORE THAN JUST —

  A COMMODITY

  IF YOU LOOK at the shared history of people and animals, the final decades of the twentieth century and the first decade or so of the twenty-first century have been positive. It’s true there are still factory farms, experiments done on animals, and other ruthless forms of exploitation; however, as we credit our animal colleagues with increasingly co
mplex emotional lives, we are extending rights to them, as well. In Germany, a law that improved animal rights under civil law (referred to in Germany by the shorthand TierVerbG) came into force in 1990. The goal of this legislation is to ensure that animals are no longer treated as objects. More and more people are giving up meat altogether or giving more thought to how they buy meat to promote the humane treatment of animals.

  I applaud these changes because we are now discovering that animals share many human emotions. And not just mammals, which are closely related to us, but even insects such as fruit flies. Researchers in California have discovered that even these tiny creatures might dream.73 Sympathy for flies? That’s quite a stretch for most people, and the emotional path to the forest is even more of a stretch. Indeed, the conceptual gap between flies and trees is well-nigh unbridgeable for most of us. Large plants do not have brains, they move very slowly, their interests are completely different from ours, and they live their daily lives at an incredibly slow pace. It’s no wonder that even though every schoolchild knows trees are living beings, they also know they are categorized as objects.

  When the logs in the fireplace crackle merrily, the corpse of a beech or oak is going up in flames. The paper in the book you are holding in your hands right now is made from the shavings of spruce, and birches were expressly felled (that is to say, killed) for this purpose. Does that sound over the top? I don’t think so. For if we keep in mind all we have learned in the previous chapters, parallels can definitely be drawn to pigs and pork. Not to put too fine a point on it, we use living things killed for our purposes. Does that make our behavior reprehensible? Not necessarily. After all, we are also part of Nature, and we are made in such a way that we can survive only with the help of organic substances from other species. We share this necessity with all other animals. The real question is whether we help ourselves only to what we need from the forest ecosystem, and—analogous to our treatment of animals—whether we spare the trees unnecessary suffering when we do this.