JoAnne Skelly: Trees ‘network’ and share resources

My friend Paul sent me a link to a fascinating TED talk by Suzanne Simard, professor of forest ecology at the University of British Columbia. She has established trees in a forest collaborate and has been researching this for 30 years. In fact, there are “symbiotic networks in our forests that mimic our own neural and social networks” (

The way trees collaborate is by using “underground fungi networks to communicate and share resources.” Her research methods involved injecting gases into plastic bags covering forest seedlings. Different types of trees growing near each other received different gases. She then ran a Geiger counter over the seedlings first to determine if the gases had been absorbed by the plants and then to see if the gases were shared between plants. She found plants absorbed the gases and also the gases were shared, even between different types of trees such as Douglas fir and birch.

Trees communicate and cooperate with each other in the language of carbon, nitrogen, phosphorus, water, defense signals, chemicals and hormones. Networks of mycorrhizal fungi mycelium coat every soil particle, creating a dense web in forest soils. There could be hundreds of miles of mycelium under one footstep.

Trees grow and use resources differently at different times of year but can share when one has high resources to one with low. Simard says there are hub or mother trees that nurture young trees and seedlings growing in the understory. These hub trees could be connected to hundreds of other trees. They send excess carbon to seedlings and they can even reduce root competition so seedlings have enough soil space to thrive. When a hub tree is dying, it sends messages to seedlings transmitting carbon and defense messages for survival. “Trees talk,” reports Simard.

Back-and-forth conversations increase the resilience of entire community.

These overlapping networks provide feedback for adaptation and survival. They’re complex systems. Taking out too many trees, i.e. by clearcutting, wildfire or beetle kill, can collapse a whole system. Simard advocates saving old growth forests because they’re repositories of mother trees, genes and mycorrhizal networks. She proposes less cutting, but when cutting occurs, keep the mother trees with their networks and genes. She says regenerate forests with a diversity of species and genotypes.

Note: There’s a free workshop, “Compost 101,” from 11 a.m. to noon Nov. 16 at the Foothill Garden located on the Carson Tahoe Medical campus near the Cancer Center.

JoAnne Skelly is associate professor and Extension educator emerita at University of Nevada Cooperative Extension. E-mail


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