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Can you hear the screams?

Posted: September 19, 2016

Listen carefully.
Photo Credit: JT Fleegle

Photo Credit: JT Fleegle

As I was scrolling through my facebook newsfeed, I came across this quote from an unknown author: "Let’s take our hearts for a walk in the woods and listen to the magic whispers of old trees…"

The thing is, I don’t think they are whispering.  A study recently published finds that trees know when they are being browsed by a deer and take action.  Yes, you read that correctly.  Trees “know” and react!

The study, conducted in Germany, looked at beech and maple saplings.  As a bit of background, the forest canopy there is dominated by oak and ash with understory regeneration mainly consisting of maples species, ash, and beech. 

Sound familiar?

So where is all this screaming coming from?  Well, it is more of a silent scream I guess.  Like Edvard Munch’s famous creation

Researchers simulated deer browsing by clipping buds off of saplings and applying deer saliva to the wound.  Sampling with this treatment increased production of salicylic acid which signals the tree to produce more tannins.  Saplings also increased their concentrations of other hormones, specifically growth hormone.  Tannins are not palatable to deer and may deter future browsing attempts. 

Saplings clipped without receiving deer saliva application did not increase salicylic acid production thereby not altering tannin or other defense metabolites levels.  Instead only production of wound hormones (i.e. growth hormones), which enhances the growth of remaining buds to make up for the lost ones, increased.  

GET OUT!

What compound the saplings are responding to in the deer saliva is unknown.  But there is definitely a measureable response!  Trees are not the stoic, passive, gentle giants of our forests.  They aren’t going to take being eaten alive lying down (or in this case standing up).  Like the Ents attack on Isengard, they aren’t going down without a fight.

So the next time you enter the forest, know that there is an epic struggle unfolding in the silence.  Instead of the magic whispers, you may hear the battle cries.

-Jeannine Fleegle
Biologist
PGC Deer and Elk Section

 

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