by Erin Marissa Russell
Many gardeners accept the sentience of plants as a fact of life. After all, there’s a reason many of us talk to, or sing to, our gardens in an effort to help them flourish. This belief is more than just an old wives’ tale. Recent research shows that sound can impact growth hormone levels in plant cells, and the roots of maize seedlings will grow in the direction of sounds of a certain frequency.
Author and forester Peter Wohlleben explains how trees communicate with one another and behave in social ways that, at times, seem downright human in “The Hidden Life of Trees: What They Feel, How They Communicate—Discoveries From a Secret World.” (Amazon affiliate link) The book is a must-read for gardeners and anyone interested in plants in general. Let’s take a look at some of the most surprising revelations from the text.
1. Like humans, trees give preferential treatment to family and friends.
Science has shown for years that plants share nutrients more freely with others that also share their genetic makeup—those one might consider members of their families. When it comes to trees, it’s beneficial to the group to keep all the trees in the forest at a baseline of health. But with some individual trees, this level of care is amped up, as if these trees have been deemed more important than others. Trees care for sick or dying members of the forest by passing nutrients through their extensive, interconnected root system. Wohlleben writes, “Every tree is a member of this community, but there are different levels of membership.” Some special trees, even when they’ve been reduced to stumps, will be nourished by the surrounding forest for centuries.
2. Trees communicate with one another through scent.
While trees don’t have a spoken or written language like humans do (as far as we know), that doesn’t stop them from sending messages throughout the forest. If an animal or insect is munching on their leaves, trees emit a warning signal using scent compounds specifically designed to sound the alarm. These scents can be sensed by other trees up to 100 yards away. In the case of umbrella thorn acacias, in response to the alarm scent, neighboring trees pump their leaves full of toxins. Herbivores won’t eat trees with the toxin present, so they move on to a stand of trees farther away.
3. Trees and insects work together to deflect predators.
Toxins aren’t the only option trees have when it comes to defense. Some species also have a symbiotic relationship with insects and work together with them to send predators on their way. For example, elm and pine trees send out scents that call in parasitic wasps as reinforcement. Though this strategy takes a while to pay off, in the end, it’s effective. The wasps lay their eggs inside the caterpillars that would make a meal of the trees, and the larvae consume the caterpillars from within as they hatch and grow.
4. Fungi do their part by carrying messages from tree to tree.
Communication in the forest isn’t limited to scent. Trees work in concert with the fungal networks that nest in their roots to make sure their messages get where they’re going. This fungal communication method can be more effective than scent, as scent must be carried by the wind and therefore won’t reach every other tree in range. The fungi system, though, doesn’t rely on weather to be effective. In addition to communicating chemical messages via scent, trees also use electrical signals to send messages to their compatriots via the fungi. This style of communication has been dubbed the “wood wide web” by many who’ve written about it, but the term was first used in the journal Nature.
5. Trees that don’t communicate suffer the consequences.
For every benefit in life, it seems there’s a downside. Trees that are less able to communicate with neighbors due to illness or a lack of fungus are targeted by hungry insects. Wohlleben explains, “It’s conceivable that to do this, insects listen to trees’ urgent chemical warnings and then test trees that don’t pass the message on by taking a bite out of their leaves or bark.” That’s why you’ll notice that trees already experiencing weakness due to disease are more likely to end up infested with insects.
6. Trees that work together succeed together.
In addition to the sharing of resources we already mentioned, when trees slip nutrients to others that need them, there’s further evidence their society is communal. While every tree has a different experience due to its location, amount of shade or sun, and soil quality, the forest synchronizes production so that photosynthesis happens equally across all its members. Trees that produce more donate more nutrients through the underground root system, and less productive trees benefit from their neighbors’ generosity.
7. Choices about reproduction are a community affair.
In the human world, reproduction is normally a very private matter. With trees, however, the entire forest often works together to ensure the most fruitful season. It’s beneficial for all the trees to bloom at once so that the gene pool is as varied as possible. Wohlleben writes that deciduous trees plan reproductive cycles a year in advance. They must choose whether to bloom or hold off a year or two for the best possible results. By delaying their bloom during some years, the trees deprive herbivores that would feast on acorns over the winter from some of their food source. This shortage cuts down the herbivore population, ensuring greater likelihood of survival the next year for the seeds.
This list of lessons from the text just scratches the surface of what there is to find out in “The Hidden Life of Trees.” Wohlleben is a capable and knowledgeable narrator, making it easy for readers to grasp concepts he’s spent his life learning about. Whether you’ve always wondered what trees are thinking or have just begun to be curious, “The Hidden Life of Trees” has the answers.
Want to learn more about how trees communicate?
The Atlantic covers The Wood Wide Web
BBC Can Your Plants Really Hear You if You Sing to Them
BBC covers How Trees Use the Wood Wibe Web
New York Times covers Loyal to Its Roots
The Secrets of the Wood Wide Web
Please note that links to Amazon from Gardening Channel are affiliate links.