11 September 2015

"Crown shyness" explained

I recently encountered the term "crown shyness."
Crown shyness is a phenomenon observed in some tree species, in which the crowns of fully stocked trees do not touch each other, forming a canopy with channel-like gaps. It is also known as canopy disengagement, canopy shyness, or intercrown spacing.
The term was new to me, but the concept was not; it's quite readily observable by anyone who spends a significant amount of time in the woods.  What did surprise me was the notion that the cause of this phenomenon is unknown; I had always assumed it was a manifestation of contact inhibition of growth. Apparently it's not so simple.

Photo credit.


  1. next time i go for a walk in the deep woods, i will have to look up. i usually look down, looking for mushrooms, seeing deer poops, and watching where i am going so i don't stumble and trip.


  2. In a recent episode of the podcast "Ologies," dendrologist J. Casey Clapp was presented with the question of why crown shyness exists. He didn't have a definitive answer but speculated that it could be because leaves and branches knocking against each other create abrasions which result in these natural spaces in the canopy. (Full episode is available at https://www.alieward.com/ologies/2018/5/7/wdppyiv1wrcs8gchoslvhhuuboanau.)


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