The Hidden Life of Trees, What They Feel, How They Communicate: by Peter Wohlleben

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“The Hidden Life of Trees, What They Feel, How They Communicate”, by Peter Wohlleben, explains why forests matter on a global scale and we learn that “that when trees unite to create a fully functioning forest that the whole is greater than its parts.”

Sociability, especially between trees of the same species, leads to the sharing of food through interconnected root systems to create an ecosystem that allows protection from the elements. A tree is only as strong as the other trees around it, and the creation of a forest allows longer lives for many of the trees. The common root system allows weak and sick trees to be nourished by the stronger ones, and sometimes it is extended to even trees of other species, often just considered competitors. 

Trees of the same species grow together best, side by side, achieving the same height. Like good friends they don’t crowd each other but grow their branches out to the tips of the neighboring tree. The trees have their most sturdy branches facing those “non-friends” of other species. The canopy created moderates heat and cold and forms a protected environment where ever tree is important to the community of trees.

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Wohlleben explains that trees communicate with electrical impulses much like humans. When we feel pain in part of our body the electrical impulse travels through the nerves and we instantly feel the pain. With trees the electrical impulses travel at 1/3 of an inch per hour and it can take a hour for the impulse to inform the tree of a problem which might be considered pain. Electrical impulses travel through the root systems to inform of issues with neighbors, sometimes even to and from other species.

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An example of this was found by scientists studying giraffes who were feeding on umbrella thorn acacias. It was clear that the trees didn’t like this at all. It took a few minutes but when this happened the trees started pumping toxic substances into their leaves and of course the giraffes got the message and left. What was amazing is that the trees notified their neighbors of the problem by giving off an ethylene gas as a warning that to neighboring trees of the same species and they then started pumping toxins. The giraffes moved away but had to go at least 100 feet away to begin eating again. The smarter giraffes moved upwind. 

Beeches, spruce, and oaks were studied Wohlleben and he wrote that when a creature starts nibbling on them they feel pain. When a caterpillar takes a bite out of a leaf, the tissue around the site changes and the leaf tissue sends out electrical signals, just as human tissue does when it is hurt. However, the signal is not transmitted in milliseconds, as human signals are; instead, the plant signal travels at the slow speed of a third of an inch per minute. Accordingly, it takes an hour or so before defensive compounds reach the leaves to spoil the pest’s meal. 

Wohlleben shows the complex ways that trees interact with their environment with a story learned with the re-introduction of wolves into Yellowstone National Park.

It all starts with the wolves. Wolves disappeared from Yellowstone, the world’s first national park, in the 1920s. When they left, the entire ecosystem changed. Elk herds in the park increased their numbers and began to make quite a meal of the aspens, willows, and cottonwoods that lined the streams. Vegetation declined and animals that depended on the trees left. The wolves were absent for seventy years. When they returned, the elks’ languorous browsing days were over. As the wolf packs kept the herds on the move, browsing diminished, and the trees sprang back. The roots of cottonwoods and willows once again stabilized stream banks and slowed the flow of water. This, in turn, created space for animals such as beavers to return. These industrious builders could now find the materials they needed to construct their lodges and raise their families. The animals that depended on the riparian meadows came back, as well. The wolves turned out to be better stewards of the land than people, creating conditions that allowed the trees to grow and exert their influence on the landscape.

Peter Wohlleben’s book is ground-breaking in what he has discovered. “He describes the peculiar traits of these gentle, sessile creatures-the braiding of roots, shyness of crowns, wrinkling of tree skin, convergence of stem-rivers-in a manner that elicits and aha! Moment with each chapter.

see American Wolf by Nate Blakeslee for more on the introduction of the Wolf into Yellowstone Park.

Quotes

“This is because a tree can be only as strong as the forest that surrounds it.” 

"There are more life forms in a handful of forest soil than there are people on the planet.”