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

Peter Wohlleben

It turns out, biologically speaking, that humans aren’t all that exceptional. We finally decoded the genome, only to discover that we share 97 percent of it with the field mouse and 60 percent with the common fruit fly. A recent spate of pop-science books sets out to remind us not only that we are descended from fish and apes but, yes, that animals are people too. We now know that few of the things we thought made us special – language, technical ability, social and emotional complexity, a sense of time – are unique to our species. Carl Safina’s Beyond Words: What Animals Think and Feel brings us dolphins and elephants that grieve. In Are We Smart Enough to Know How Smart Animals Are?, zoologist Frans de Waal implies that most zoologists preceding him were not, devising tests for clever bonobos and gibbons unjustly biased toward a human skill set. And Jennifer Ackerman’s The Genius of Birds shows how much we have underestimated the bird brain. To anyone who’s ever had a pet dog, none of these discoveries come as a great surprise.

Now this. Trees, too, may have feelings, and seemingly complex social lives as well. They love, grieve, talk, warn each other of danger, share resources with struggling neighbors, nurture their offspring, and support aging parents. When German forester Peter Wohlleben stopped going by the logging textbook and started listening to what his trees were trying to tell him, a whole new world opened up.

For one, the beeches native to his Central European forest actually want to grow closely together. If one tree is diseased or struggling on poor soil, its neighbors pass it nutrients, banding together to maintain the canopy that keeps sun and wind out and precious moisture in.

Each species competes ruthlessly with other species, and each has its natural enemies. Yet trees also enjoy a host of mutually beneficial relationships with fungi and insects. If attacked by a particular caterpillar, the oak releases a scent to summon a specific wasp to lays its eggs in the pests. Oaks and beeches throughout a forest can conspire to withhold their seeds for several years at a time to starve deer and boar populations that would otherwise eat all the acorns and beechnuts. When giraffes come to browse, umbrella thorn acacias start producing a foul-tasting toxin in their leaves. They also release a gas, ethylene, onto the breeze to alert nearby trees to start producing the same toxin. (The giraffes have learned to skip a few trees or move upwind.)

When it comes to how trees “think” or where their “brain” or “memory” resides, Wohlleben veers into speculation. He notes that not unlike our own neurons, roots have been overheard transmitting electrical impulses – at 220 hertz – to which other plants react, and that scientists now believe these communications are facilitated by a “wood-wide web” of fungal mycelium. Whether or not such comparisons to human intelligence are overblown, Wohlleben’s fascinating book is a good place to start to recover a sense of wonder toward the created world around us.