I’ve always loved the fictional forests in Greek mythology or “The Lord of the Rings” with their dryads or Ents, trees that are personable, that interact, and communicate with each other. But I never thought of the actual forests in reality as much more than spaces where trees grow next to each other. They provide ecosystems for other species, I knew that much. I assumed that individual trees were isolated from each other and focused on their own individual growth or reproduction.

Then I read Peter Wohlleben’s “The Hidden Life of Trees.” His scientific yet conversational bestseller describes many fascinating aspects. But, the most memorable chapters are the ones that explain how trees communicate.

Forest trees, so I learned from Wohlleben, are incredibly interconnected with each other through their roots and fungal systems attached to roots. It's in every tree’s interest to keep the climate around them stable, so healthy trees will use the underground connections to share sugars with young or sick trees nearby. Not only this, but tree roots recognize roots of trees that are siblings. They respectfully keep their branches out of their relative’s space.

Another common tree interaction is to warn other trees about predators. Wohlleben gives the example of thorn acacias in the African Savannah. A Thorn Acacia will release a special gas into the air when giraffes eat its leaves. This triggers nearby trees to put up toxic defenses to ward away the giraffes. Other trees may send warning chemicals through the fungal root system.

Wohlleben also discusses new research on other ways trees may be communicating: through sound waves! One study performed on grain plants by Dr. Monica Gagliano of the University of Western Australia showed that root tips make a high crackling noise of about 220 Hertz. When exposed to this sound, root tips of other plants will grow towards the other roots. The roots were listening for other plants!

Wohlleben explores this and many other topics in “The Hidden Life of Trees,” like how trees learn, sleep, age, and compete. Wohlleben also teaches his readers how to recognize the signs of interaction between trees during ordinary walks in the forest. Now every time I see the arboretum behind my dorm, I think of all the conversations those trees are having…