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Written By Karl VonBerg.

Posted on August 2nd, 2022.

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Did you know that trees in a woods can communicate with each other and the animals in the woods?  They send out information when they are getting attacked.  Information that helps others come to their rescue.  Check out how this works.

Have you ever heard a tree scream?  Me neither.

Large cherry tree

But they do let others know they need help. 

Some researchers in Germany set up an experiment* that helps unlock the fascinating details of what goes on when caterpillars start chewing on the leaves of a tree.

Spongey moth caterpillar chewing on a leaf

Each species of tree has a unique “bouquet” of volatile organic compounds (VOC) that it gives off.  Insects and birds can distinguish the VOCs that tree species give off.

Let’s check out the sequence of events leading up to a tree’s leaves getting eaten and the tree’s response:

 

3 tree response to insect attack

Sequence of events leading up to a tree’s leaves getting eaten and the tree’s response

Obviously, this relationship doesn’t always prevent a tree from being defoliated.   Gypsy moths wreaking havoc on an oak woods or forest tent caterpillars stripping a sugar maple woods show us that.

3 tree response to insect attack

Spongey moth defoliated woods

But perhaps, major defoliation is slowed or stopped more often than we realize by the sequence of events above.  This natural control of the population of caterpillars chewing on leaves early on may prevent a major defoliation from happening in the future.

What I find interesting is just how intricate the system is that allows a tree to protect itself.  We are just beginning to learn about the communication that goes on in a woods between individual trees of the same species, between tree species, and between trees and animals (insects, birds, etc). 

Trees communicate via more than just scent (volatile organic compounds or VOCs).  They communicate:

  • Internally through transport of chemicals in the phloem (living transport system) of the tree
  • Between trees through chemicals transported between tree roots via connections made by mycorrhizal fungi (beneficial fungi that provides increased water and nutrient uptake) attached to the roots.

Why not take a walk in a woods and contemplate what communication might be going on between the trees and animals in the woods?


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