ENGAGE • ENLIGHTEN • INFORM
ISSUE 5. SUMMER 2023
The Hidden Life of Trees: What They Feel, How They Communicate by Peter Wohlleben
By Fiona Poth
In 2019, a Swiss scientist, Tom Crowther at Swiss University ETH Zurich, developed a new hypothesis: Planting one trillion trees would help avert the threat of climate change. Trees have the ability to capture a large amount of CO2 every day through the process of photosynthesis. The scientists calculated that, over several decades, these new trees could remove almost 750 billion tons of CO2 from the atmosphere. So, trees have the power to save the world, but did you know that they can communicate, count, and care for each other?
Peter Wohlleben spent twenty years working for Germany’s Forestry Commission. During that time, he gathered a wealth of information about trees and how they interact with one another. The title of his 2015 book might suggest that he is trying to anthropomorphize the flora he came to know so well. Like Disney before him and the familiar attempt to give Bambi and Thumper human characteristics, recognizing that trees think, feel, communicate, and live in social networks might seem, at first, to be an effort to give them human qualities so that we can relate to them more readily, but Mr. Wohlleben’s observations about trees are well founded in science and his years of observation.
It turns out that trees do have a system of communicating their feelings with each other and of sharing resources and caring for one another, but this happens on a time scale that is exceedingly slow from a human perspective. Trees typically use their root systems as well as a network of fungus that grows between their roots to share information. Simple information, like indicating a loss of nitrogen, can take hours, days, and even weeks to communicate from one tree to another.
In some respects, by describing how tree communities in forests communicate and cooperate with each other, Mr. Wohlleben provides an example of where Darwin’s “survival of the fittest” does not strictly apply. Mr. Wohlleben observes that “a tree can be only as strong as the forest that surrounds it.” He found that, instead of competing with one another for resources and sunlight, trees cooperate with each other. A tree that receives abundant sunlight that allows it to photosynthesize more sugar than it needs will share its excess nutrients with other, shorter trees nearby. This happens even between trees of different species. Other trees will keep a sick and dying tree alive for long periods by sharing nutrients with it even after it has lost all its leaves. Thus, trees that live in forest communities have been observed to live far longer than solitary trees that are isolated from other trees. Rather than “survival of the fittest,” this demonstrates the importance of community and cooperation in the health and life of trees.
One of the more interesting observations Mr. Wohlleben provides is that trees count. Particularly in the spring, trees need to know when the weather has warmed sufficiently to permit a productive use of leaves. If they put out their leaves based on one or two days of warm weather in March, they may face a cold snap in April and May that kills their leaves and severely limits their ability to gather and store nutrients during the summer. As a result, many trees will not sprout leaves until a set number of warm days has occurred in a row. This requires the trees both to count the number of warm days and to have some form of memory so that they know the total number of days that a particular weather pattern has lasted.
Parks and forests play a critical role in the health of our environment. Over the past several years, people have come to appreciate them even more because they have offered one of the few places where “socially distanced” outdoor experiences could be enjoyed. If you want to have a better understanding of the near-magical qualities of the trees that anchor these places, The Hidden Life of Trees is a book well worth reading.