Crown Shyness, A Natural Phenomenon Where Trees Avoid Touching

Crown shyness is a naturally occurring phenomenon in some tree species where the upper most branches in a forest canopy avoid touching one another. The visual effect is striking as it creates clearly defined borders akin to cracks or rivers in the sky when viewed from below. This intriguing behavior was first observed in 1920’s, but somehow researchers yet have to reach a consensus on what causes it.

Thus, various hypotheses have been presented since then in an attempt to explain it. It might simply be caused by the trees rubbing against one another, although signs also point to more active causes such as a preventative measure against shading (optimizing light exposure for photosynthesis) or even as a deterrent for the spread of harmful insects. Some believe it occurs to reduce the spread of harmful insects, while some believe that trees are attempting to protect one another's branches from getting cracked and broken in the wind, and it's also been suggested that "crown shyness" happens so that trees can optimize light exposure in order to maximize the process of photosynthesis.

One theory suggests that this empty space around the crown might be caused by breakage of twigs and branches from violent collision that happens during storms and high winds. Experiments show that if trees with crown shyness are artificially prevented from swaying and colliding in the wind, they slowly fill in the empty space in the canopy. Similarly, some research suggests that continuous abrasion at growth nodules disrupts bud tissue such that it is unable to continue with lateral growth. Despite these various theories however, nobody knows for sure why this occurrence occurs, but it serves to remind us of just how breathtaking Mother Nature can be. The next time you're out walking through the forest, take a moment to look above you and you might be pleasantly surprised by what you find.