Cape Ann Vernal Pond Team

Biologist Nathan Mineo

Did You Know...?

Trees Can Talk

Written by Nathan Mineo 
Reprinted from the 2018 Cape Ann Vernal Pond Team Newsletter
Photograph by Cheryl Briscoe
Did you know that trees can talk? Actually, this isn’t anything new. It’s long been known that trees and other plants can communicate with one another using pheromones. One of the most famous examples is the iconic acacia tree of the African savanna. When a giraffe starts browsing on the leaves, it triggers the tree to produce high levels of poisonous tannins in the leaves, making them inedible. Also produced is a distress pheromone that is released from the leaves of the browsed tree, carried by the wind to the leaves of other acacias in the area, who then also start to produce high levels of poisonous tannins. Now that all the acacias in the area have inedible leaves, the giraffes have to move on.

Plant communication doesn’t only come from the leaves, however. Sometime in the late 80’s, scientists found that plants can communicate underground. Not only communicate but help each other out by sending carbon and other nutrients to trees in need. The fact that trees can do this is incredible! Even more incredible is how they do it. Growing amongst the roots of every plant sprouting from the Earth is mycelia. Mycelia is fungus — it’s kind of like the “roots” of a mushroom. Mycelia and plants have a mutualistic relationship. The plants provide the fungus with sugars, the fungus provides the plants with nutrients like nitrogen and phosphorus, and help the plants absorb water. The mycelia connect to one another, and connect plant to plant, and tree to tree, in what are called mycorrhizal networks. These mycorrhizal networks give entire forests a communication and delivery system. One of the leaders in this field of research, Susanne Simard, calls it “tree talk”. Simard was the first to study this in an actual forest and confirmed that trees can send carbon to one another via mycorrhizal networks. Since then, much has been learned. Trees can recognize and favor their own kin, they can supply nutrients to seedlings to help them establish, different tree species can swap resources, water can be transferred to help trees avoid drought stress, signals can be sent to trees to help them defend against attack from insects like aphids, the list goes on. Researchers have even mapped out these mycorrhizal networks and the connections between trees in forests. They found that older trees have more connections and therefore have more influence on the rest of the forest. Simard calls these trees “mother trees” (aka hub trees). Mother trees have the ability to help forests recover faster from disasters, such as logging, because they “nurture” their young by sending them nutrients. Identifying and preserving mother trees could be an important part of sustainable forestry.

The secret world of trees is fascinating!  Just think, when you are walking among them, they are talking and caring for one another. Hopefully that changes your perspective of trees and forests the same way it has changed mine.

     Photograph of the ever so humble, hobble bush
         (Viburnum lantanoides) by Nathan Mineo

For more information on this topic, check out Susan Simard’s TED Talk at:
https://www.ted.com/talks/suzanne_simard_how_trees_talk_to_each_other 


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