62 pages • 2 hours read
Peter WohllebenThe Hidden Life of Trees: What They Feel, How They Communicate—Discoveries from a Secret World
Nonfiction | Book | Adult | Published in 2015A modern alternative to SparkNotes and CliffsNotes, SuperSummary offers high-quality Study Guides with detailed chapter summaries and analysis of major themes, characters, and more.
Chapters 33-36Chapter Summaries & Analyses
Chapter 33 Summary: “Healthy Forest Air”
Wohlleben begins Chapter 33 by explaining how forests clean the air. He compares the forest to a filter since it effectively traps dust, pollen, and human pollutants from circulating in the air. Trees also release phytoncides and other scents into the air that have a cleansing effect. He cites a Korean study which showed that forest walks improved walkers’ blood pressure and lung capacity. The author offers the explanation that people may be able to pick up on the “swirling cocktail of tree talk” happening around them in undisturbed forests (223). Wohlleben also claims that in unhealthy forests humans may be able to pick up on the “alarm calls” that distressed trees send out to each other.
Each square mile of forest produces about 29 tons of oxygen per day, enough for 10,000 people’s daily oxygen needs. He notes that this oxygen production decreases at night, when trees are using their carbohydrates and release more carbon dioxide. Rotting leaves and wood also release carbon dioxide as they break down. Wohlleben explains that in the winter forests produce much less oxygen, and credits marine algae with solving the “oxygen deficit” in central Europe. These algae produce oxygen which arises from the oceans and is moved inland by winds.
He then examines trees’ respiratory systems, explaining that tree leaves and roots have openings where they breathe in carbon dioxide and exhale oxygen. If the soil around tree roots is too compacted, the tree could die of asphyxiation. The author concludes this chapter by noting that ‘sleep’ is an essential aspect of trees’ lives. He provides the example of oak and beech trees dying when grown indoors due to the constant heat and artificial light which prevents them from maintaining their natural cycles.
Chapter 34 Summary: “Why Is the Forest Green?”
Light and tree biology have created the colors human experience in the forest environment. He begins by interpreting the weather from the trees’ point of view. He explains that while humans may find blue skies relaxing, trees consider it a “buffet” and a signal to be as productive as possible converting the sunlight into food (227). He writes that because trees and other plants are absorbing this light by using chlorophyll, they appear green to human eyes because of chlorophyll’s “green gap” (228). Chlorophyll cannot utilize green light and so it “reflects it back unused” (228). This phenomenon is also responsible for creating “green shadows” which allow more sunlight to reach the forest floor (228).
The author discusses why people have a difficult time relating to trees and perceiving them as beings, rather than objects. He suggests that trees’ slow growth and long life spans make them seem “static” to people, and much of their life cycles and behavior are hidden from us (230). He notes that even forestry experts and environmental conservationists can underestimate the amount of forest species since animals and insects that evolved to live in forests are often quieter and more subtle than meadow species.
Chapter 35 Summary: “Set Free”
In Chapter 35 Wohlleben discusses forest conservation efforts around the world. He acknowledges that due to environmental destruction around the world, there is a growing movement to permanently preserve forest ecosystems, especially old growth forests. He celebrates that certain old forests in the US, Australia, Canada, and the UK are legally protected from logging, and reports that Germany has preserved about 5% of its old growth forests. He explains that this type of ecological protection is called “process conservation” because these spaces are not managed by people, but instead left to their own natural processes (235).
Wohlleben explains that if the landscape is recovering from human interference, these natural processes can take decades to produce a healthy forest of native trees. He also addressed the perception that unmanaged forests become overgrown and “impenetrable” and argues that the opposite is true: disturbed forests let in more light and therefore produce thicker understory growth, while old growth forests shade the understory effectively and are actually more accessible to people. He clarifies that old growth forests are less vulnerable to storm damage including hazards like falling branches. The author concludes this chapter with his own plea to the reader to “have a bolder approach to wilderness” (239).
Chapter 36 Summary: “More Than Just a Commodity”
Wohlleben feels that in the last few decades the world has seen positive gains towards increasing animal rights. He reiterates that people find it more difficult to sympathize with plants than with animals, and he points out that while we acknowledge they are living beings, we still refer to them as objects. He draws parallels between plants and animals, since they are all living beings that we exploit for our own purposes, and he anticipates that plants will one day enjoy more rights that recognize their unique needs. He argues that it is morally sound to use forestry products only if “trees are allowed to live in a way that is appropriate to their species” (242). He claims that this includes establishing social connections, growing in unaltered soil and surroundings, and helping younger trees grow.
This ethical approach to silviculture is the forestry equivalent of organic agriculture. He argues that as new research helps humans understand more about plant life, our relationship with trees will change as people become more sensitive to their needs and understand how their natural systems can benefit our communities. He concludes his last chapter by reminding the reader not to succumb to a narrow-minded view of trees as merely materials for humans to harvest. He encourages the reader to enter the forest with a sense of wonder and curiosity for the “daily dramas and moving love stories” that occur every day in the forest (246).
Chapters 33-36 Analysis
Wohlleben’s final chapters revisit the theme of human perceptions of nature. He reiterates that there are many reasons why people objectify plant life, lamenting that “many people today see trees as nothing more than objects” (230). He cites trees’ slow growth and long life spans and their hidden functions as primary reasons for this objectification. He then explicitly makes the connection between people’s perceptions and knowledge of the forest with their actions. For example, he examines how politicians and the public are often impatient and do not want to view dead forests or waste planted conifer trees. He argues that these perceptions of waste or ugliness do not consider nature’s systems. He argues that allowing these former commercial forests to die naturally is an essential step in establishing a new healthy forest, since their rotting wood will help the new trees grow.
In another example he explains that even professional foresters or environmental conservation experts can be prone to bias due to their own misconceptions of nature. Because most meadow species are more showy, colorful, and obvious to the human eye, some people see them as a beneficial presence in the forest. Wohlleben reports that as a result, many professionals are happy to see clearings in the forest since “they truly believe the open space increases species diversity, and they miss the fact that this is traumatic for the forest” (232). He debunks the myth that creating clearings improves forest health and explains that it actually introduces more conspicuous meadow species at the expense of the native forest plants and organisms.
Adding to his commentary on human perceptions of nature, Wohlleben offers his own hypotheses for why ancient forests in particular appear to have a beneficial effect on people. He suggests that humans have evolved to intuitively register the state of the forests’ health and unconsciously understand the trees’ signals to each other. He writes that “in ancient beech forests fewer ‘alarm calls’ go out, and therefore, most messages exchanged between trees are contented ones, and these messages reach our brain as well, via our noses.” Therefore, Wohlleben is “convinced that we intuitively register the forest’s health” (223).
Wohlleben strikes a positive and optimistic tone in his last chapter as he expresses his hope that people will continue to expand their knowledge about the world of plants. He shares his expectation that our new discoveries will enhance our perception of trees and help us establish a more respectful and productive relationship with the forest. He raises the idea of plants having rights as an excellent approach to the human-plant relationship and cites examples of countries such as Switzerland where this is already the case. Significantly, while Wohlleben has written extensively about human destruction of and misinterpretation of the forest, he does not conclude his book with a guilty or negative tone. Instead, he encourages the reader to delight in the forest and use their own powers of observation and imagination to enjoy and understand the trees around them more fully.
