Tree Talk

Aug. 18, 2019

I recently watched a TED talk by Suzanne Simard, a forest ecology scientist who has worked up in Canada for the pass 30 years. She told an interesting story about what first peaked her interest in what is going on beneath the soil in a forest. The family dog fell down into the hole in the outhouse. Her grandfather had to dig through the ground to get the dog out. While her grandfather was digging, she became engaged by the massive tree roots and fugal growth under the ground- a whole world that very few people were aware of.

Her research involves studying the connections and cooperative behaviors of this underground network. She began by seeing if trees transfer carbon to one another. She worked with birch, firs and cedar trees. She hypothesized that the birch and firs would be connected in their own underground web, but not the cedar. Undeterred by bears, she covered the seedlings with plastic bags, filling them with various types of carbon gas. She injected a radioactive gas into the birch, and then a stable carbon dioxide gas into the fir.

When she ran a Geiger counter over the trees, she discovered silence from the cedar, and a loud sound of communication between the fir and birch trees who were sharing carbon with each other. She discovered birch sent carbon to fir, especially when it was shaded. Later the opposite happened, when the birch was leafless in the winter, the fir sent over more carbon. 

Science had always believed that trees competed with each other for carbon, sunlight, water and nutrients. Simard’s groundbreaking work showed that trees are interdependent and cooperative, in fact they are immersed in deep relationships with each other. The trees were conversing by chemical and hormonal signals via the mycelium. These messages determined which trees needed certain nutrients. They communicated via carbon, nitrogen, phosphorus, water, hormones and chemicals and then shared these elements, balancing the entire forest. A massive web of hair-like mushroom roots transmit secret messages between trees, triggering them to share nutrients and water with those in need.

The web is so dense there can be hundreds of kilometers of mycelium under a single foot step. And the mycelium connects different individuals in the same forest, from the same species and other species. This network works in a similar way to the internet. She discovered that mother trees nurture the younger trees and that a single mother tree can be connected to hundreds of other trees. Trees talk, and through these conversations they increase the resilience of the whole community. Trees and other forest organisms depend on each other for their survival. It’s a magical community of trees all supporting each other as well as providing habitat to a myriad of other creatures.

“A world of infinite, biological pathways that connect trees and allow them to communicate, and allow the forest to behave as if it’s a single organism.”

Suzanne’s research has important environmental implications for the destruction of our forests. She says that when mother trees are injured or dying, they send nutrients onto the next generation, but they can’t do this is if they are all wiped out at the same time. She hopes that her research will change the way we practice forestry. You can take out one or two hub trees, but there comes a tipping point, if you take out one too many, the whole system collapses. We are steadily weakening our forests, by clear cutting and planting only one or two species. This is having major environmental impacts. But there is hope. She says forests have an enormous capacity to self-heal.

It is amazing to me how me we don’t know or comprehend about the complexity of ecosystems. Most people are unaware of the complex communication system below ground that interlinks trees, fungi, bacteria as well as the abiotic nutrients shared between them. I have heard many people discussing nature in terms of survival of the fittest, eat or be eaten. Perhaps that is a cultural framing influenced by the capitalistic economic system that pervades our lives. That is a competitive system, but it is not the main driver of sustainability and evolution in nature. Yes, there is competition in nature for limited resources, mating etc, but cooperation is also a norm of nature. A balance of the two results in resilient systems. Our culture too often stresses competition and yes, the herd must be culled, but cooperation and communication is just as vital for sustainability.