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Crown Shyness

Mellow

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Pictures of a phenomenon called "Crown Shyness" pop up on Facebook from time to time. Is this a real thing? Has anyone here observed it in the field? These two pictures appear to show the canopies as a two-dimensional image but trees are three-dimensional. It would be extremely difficult to get a picture from the ground showing this simply due to the way branches grow.

Crown Shyness 1.jpg Crown Shyness 2.jpg
 

stig

Patron saint of bore-cutters
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I googled it and there are a LOT of different pictures.
Be a lot of work to fabricate all those just to prove a kooky theori.
 

DMc

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It has been talked about for years, and examples of the outcome are well documented. Nothing I have read leads me to believe anyone has a firm grasp on the "how" that enables it.
 

lxskllr

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Looks like a fairly limited group of trees that does it. Most people could probably go their whole lives looking at trees, and not see it happen.
 

DMc

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I'm willing to bet almost everyone here has seen it, just not recognized it. It is what is responsible for the separation, and layering of limbs we will sometimes see within a canopy. The pictures on the net are mostly dealing with entire outer canopies of multiple trees. Dramatic but much more rare.
 

cory

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I've never noticed it, been looking at trees since'77, but Imma keep an eye out for it.
 

BeerGeek

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I believe I stumbled across one of these on an old bike trail here in NJ back in the early 90 's. Of course, being the delinquent bone-head I was back then, I din't pay it much mind....
 

Marc-Antoine

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I saw a study at ground level, in a green house. I don't recall the specie(s). They found that the tip's growth can be inhibited by a mechanical contact, then kicks in again after a little time. Say a hand's sweep for example, not a hammer blow ! A repeated contact between the crowns /limbs by the wind should freeze them as is on their sides.
It's obviously species dependent, seeing the mess done by some trees planted in edges, like hawthorn, Leylandii or Pyracantha.
 

SeanKroll

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You ever notice how trees sometimes almost grow into the profile of a truck on streets' edges?

Part of that is pruning. I wonder if part of it is from mechanical contact ????
 

Marc-Antoine

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It's hard to tell. Beside the truck pruning, that's sure.
The strong air flow extremely turbulent at close proximity of the passing truck doesn't make for a quite growth, even without direct contact.
 

lxskllr

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If someone wanted to, you could probably experiment on a tree to see if you can affect growth. Go out every day and whack it with a stick. Not enough to break branches(or too many anyway), but knock off some leaves, and just let it know you were there. See if it reacts over time, and get a close look at the branches to see if they look different.
 
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