So Apparently, Trees Talk To One Another

Written by Sophie Fitzgerald, ESLLC 2016-2017

Suzanne Simard – How Do Trees Collaborate?

Suzanne Simard is a professor of forest ecology at the University of British Columbia.  Her passion lies in understanding the complex nature of the forests around her home in Canada.  30 years ago, Simard hypothesised that the extensive root networks created from microryza pathways could transmit information between trees… almost like neurological and social networks found in humans.  There is a standing theory that everything in nature exists in fierce competition, but Simard theorized differently.  She speculated that trees contained the ability to survive collaboratively, in the same way complex organisms form mutually beneficial communities.  Her assumptions were based on one lab’s findings and her own experience exploring the forest undergrowth.  In her 2016 TED Talk, she discussed her research on the wild idea that there was a symbiotic relationship between trees.

Forests contain “infinite biological pathways,” she explains, and “behave as a single organism.”  She tested her hypothesis by growing douglas fir and paper birch trees naturally in the forests of Canada.  The seedlings were then covered in bags, and a selected few were injected with CO\2 containing the radioactive marker C-14 isotope.  She waited an hour for the CO\2 to be absorbed by the seedlings and then held a geiger counter over the non-injected seedling and found they were also radioactive.

This completely proved her hypothesis.  Trees used unground networks to transmit carbon, water, and nutrients to one another.  Essentially, trees communicated information.  After further investigation, Simard understood that the trees utilized the mycorrhizal fungus in their roots to connect.  Mycelium are the fungal threads that extend far beyond the tree roots into the soil that connect the fungal colonies, and thus the trees, to each other, and allow this “below ground communications network” to exist.  In the summer, Simard found that the birch trees gave more carbon to fir trees when they were shaded and couldn’t photosynthesize as efficiently, and in the winter the evergreen firs sent carbon to the birch trees who lost their leaves.

The information gets even more unbelievable.  Simard took her studies a step further: could mother trees – crucial trees in a community connected to hundreds of other secondary trees – detect their own saplings from stranger seedlings?  The answer: yes.  Again C-14 was tracked as carbon was relocated from tree to tree.  Simard found that mother trees were sending more carbon and defense signals to their own offspring than they were to the foreign seedlings.  These mother trees are key to healthy, prospering forests.  According to Simard, they “increase community resilience,” and  based on her findings, we as species need to find more “holistic and sustainable” methods for clear cutting.

To her, the forest are reminiscent of human families and communities.  The interconnectivity of the trees proves the existence of communication, feedback loops, adaptation abilities, and hubs that seem almost sentient.  But the networks also make the communities very susceptible to disturbances like logging and bark beetles.  Taking out a few mother trees can collapse an entire community.  Canada, unfortunately, had the highest forest disturbance rate of any country in the world in 2014.  Annually, 3.6% of trees were being killed off, 4x a sustainable rate.  The problem was not only clear cutting, wildfires, and bark beetles, but also the replanting of forests with less diverse trees, making them more vulnerable and at risk for disease.

But the forest, because of their mycelial connection, have a remarkable ability to self-heal.  Simard proposes three solutions at the end of her talk.  The first is to transition to local enforcement of forests.  Currently, forests are protected by a one-size-fits-all mentality, but a better model would be to apply local knowledge. The second solution is to avoid cutting down mother trees.  Logging is a necessary practice, but if mother trees were avoided, the ability of the forest to grow back would increase exponentially.  There is a need to preserve the old growth forests and utilize the repository of mycorrhizal networks.  The last point she made was to regenerate the forests with diversity in order to strengthen the community.

Simard found that the forests work on an interconnected, interspecies level we never understood before.  It is proof that organisms in nature can exists using an almost compassionate level of cooperation.  Simard believes that this knowledge should shape the future of logging, and that it can lead to a more sustainable relationship between us and our forests.

Simard’s 2016 TED Talk aired today [01/16/17] on the TED Radio Hour during the episode Networks.  For more information, listen here on

How Do Trees Collaborate?:


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