How trees talk to each other

How much do you understand those old familiar trees you enjoy each day from the window or porch? What goes on between your trees?

One of my favorite scientists since seeing her enthusiasm on a Ted Talk is Dr. Suzanne Simard, author, professor, and forest ecologist at the University of British Columbia. Her research began 17 years ago.

She found that trees communicate their needs to other trees and, in return, send other trees what they need, by using an existing underground network. How do trees do this? Mushrooms.

Mushrooms are the fruit of the entire organism referred to as fungi (pronounced fun-guy). Fungi makes a dense, hair-like filigree of underground networks of roots.

This superhighway of fungi roots is called “mycelium,” and joins up with the finer root tips of trees.

As it turns out, nearly all trees cooperate with fungi to communicate with other trees and species. The term “mycorrhiza” is used to refer to this tree-fungi partnership produced by the network.

Mycelium will procure nutrients and water and send it back to the tree when needed. Since fungi is unable to photosynthesize, the tree will reciprocate with the sugar-like substance made during their own photosynthesis.

An important find by Simard is the “hub trees,” usually the largest trees around, are connected by mycelium to all the younger trees and send them more mycelium and carbon to help grow and stay healthy. And as these hub trees die, they send their wisdom on to the others.

Peter Wohlleben, a German author and forester is another important figure. He was once in the logging business and did business pretty much the same way they do here in the PNW, except he was taught to thin, not clear-cut.

After 20 years, he could no longer see trees as a commodity as he began reading early research by Simard and others around the world regarding the mycorrhizal network. “When you know that trees experience pain and have memories and that tree parents live together with their children, then you can no longer just chop them down and disrupt their lives with large machines,” Wohlleben says.

The “mycorrhizal network” also enables trees to send out distress signals via smell, taste, and electrical impulses, which is done by sending chemical, hormonal, and slow-pulsing electrical signals, per Wohlleben.

Trees send scent signals. He says trees notice injury from animals/insects (ex., deer/caterpillar) eating its leaves. This distress signal is a gas. Trees downwind sense the smell of the gas through their leaves and begin pumping their own leaves with tannins. Some trees can detect different saliva from different species of predators and release chemicals (with pheromones) making the leaves taste bad to them. Tree electrical distress pulses “travel at the speed of a third of an inch per minute,” Wohlleben says.

Our world is going through an extremely dangerous pandemic, but we still have the lethal problem of our climate emergency. We know our forests are essential in their capacity to capture and store carbon from the atmosphere. Forests are the lungs of Earth.

Our policy makers must wake up from their broken capitalist dreams. The selling of our forests by a few greedy corporations puts the well-being of all living beings in jeopardy and should be a most serious crime.

Marylin Olds is an opinion columnist. Reach her at