Have there ever been times that you just wanted to set a 360-degree no touch zone around yourself? I feel that way sometimes in super-crowded situations such as rock concerts, state fairs or even the city subway. What if I told you that this human sentiment for personal space also exists in the plant world – that there are trees that don’t touch each other deliberately? When trees have an aversion to being “touchy feely,” it’s referred to as crown shyness in trees. Read on to learn more and discover what causes crown shyness.
What is Crown Shyness?
Crown shyness, a phenomenon first observed in the 1920’s, is when the crowns of trees do not touch. But what exactly is a crown? It is the uppermost part of the tree where branches grow out from the main trunk. If you were walking in the forest and looked up, you would be looking at the canopy, which is a collection of crowns. Typically, when you look into the canopy, you see an intermingling of branches between the crowns of the trees.
Not so with crown shyness – the tops of the trees simply do not touch. It is an eerie phenomenon to behold and if you
Others have likened the appearance to a backlit jigsaw puzzle. Whatever description strikes your fancy, you get the general idea – there is a definitive separation and boundary, or “no touch zone,” around each tree crown.
What Causes Crown Shyness?
Well, no one is really sure what causes crown shyness, but multiple theories abound, some of which are more plausible than others:
- Insects and Disease – If one tree has “cooties” (such as leaf-eating insect larvae), then the spread of harmful insects is a little more difficult without a “bridge” to get to the next tree. Another hypothesis is that crown shyness prevents the spread of some fungal or bacterial diseases.
- Photosynthesis – Photosynthesis is facilitated by allowing optimal light levels to penetrate the canopy through the empty spaces around each crown. Trees grow in the direction of light and when they sense the shade from neighboring tree branches, their growth is inhibited in that direction.
- Tree Injury – Trees sway in the wind and thrash into one another. Twigs and branches get broken during the collisions, disrupting or damaging growth nodules, creating the gaps around each crown. Another related theory is that crown shyness is a preventative measure in that it allows trees to minimize or avoid this injury altogether.
What are Some Trees That Don’t Touch?
After reading this article, I’m sure you’re already putting on your hiking boots ready to journey into the woods in search of crown shyness in trees. You may discover that this phenomenon is somewhat elusive, causing you once again to question “Is crown shyness real?”
This is due to the fact that only certain types of towering trees seem predisposed to crown shyness, such as:
- Sitka spruce
- Japanese larch
- Lodgepole pine
- Black mangrove
It occurs primarily in trees of the same species but has been observed between trees of different species. If you are unable to view crown shyness in trees firsthand, google some of the places renowned for this phenomenon, such as the Forest Research Institute of Malaysia, in Kuala Lumpur or the trees at Plaza San Martin (Buenos Aires), Argentina.