Social distancing is quite familiar for us these days because of the COVID-19 pandemic. But have you ever heard that trees are maintaining social distancing way before COVID-19? Amazing, isn’t it? This phenomenon is known as ‘crown/canopy shyness’, where the treetops avoid touching each other by creating channel-like boundaries among themselves at the canopy level. The visual aspect of crown shyness is breathtakingly artistic, and it resembles the bird’s eye view of rivers! You might have seen crown shyness which looks like a giant jigsaw puzzle when you look up at the sky in some forests.

This mind-blowing natural phenomenon was firstly described in the 1920s and the term ‘Tree Shyness’ was introduced in the 1950s by the botanist Maxwell R. Jacobs. Since then, this has been studying extensively for decades in order to investigate the reason for the occurrence of this ‘social distancing’ among trees. Other than some hypotheses and theories which have been suggested to explain crown shyness, the exact physiological basis behind this mysterious behaviour of trees is not unraveled yet.

Crown shyness does not occur between all types of trees. Most commonly, it occurs between the trees of the same species. However, there are some incidents where crown shyness occurs between trees of different species as well. More interestingly, crown shyness can also be seen between independently swaying branches of a single tree.

But how do trees have their own space? Some scientists suggest that shyness gaps can be formed due to the abrasion between the branches by wind. However, it has been discovered that the wind is not the only reason behind crown shyness because the studies conducted in Malay camphor trees (Dryobalanops aromatica) have not shown any abrasions between trees. Furthermore, crown shyness was not significantly prominent in trees which are exposed to high winds than that of in less windy areas. Hence, scientists have suggested another hypothesis where the trees stop growing by sensing light through their growing tips when they are near to the branches of the neighbouring tree. There is another hypothesis which suggests the influences exerted by individual trees on each other result in shyness gaps. These two hypotheses focus on minimizing competition among trees for resources such as light which is essential for photosynthesis. In addition, there is one more hypothesis which explains the formation of these gaps in terms of allelopathy. This hypothesis is quite interesting because if this is true, it means trees communicate with each other using chemical compounds and notify the neighbouring trees to halt their growth towards them. It is believed that the real reason behind crown shyness is quite a combination of all these hypotheses rather than a single specific theory.

Amidst all these theories and hypotheses explaining the potential mechanisms of the occurrence of crown shyness, there are some other suggestions which describe the benefits of this peculiar phenomenon. Shyness gaps allow light to reach the forest floor nurturing the lower canopy trees including shrubs and ground cover. Moreover, trees can minimize the effects from wind, harmful flightless insects and pathogens by avoiding physical touches among each other. Trees can also avoid the spread of invasive lianas by having crown shyness.

These natural phenomena always remind us how astonishing and mysterious our mother nature is. Being sessile and silent, isn’t it amazing how trees respond to each other and communicate among themselves? See how respectful and cooperative they are! So next time, when you are walking through a forest, do not forget to look up at the sky and enjoy the magnificent view of crown shyness. And also, spare some time to capture an instagrammable photo of this panoramic spectacle of timid treetops.

References:

https://www.treehugger.com/what-is-crown-shyness-4869713

https://www.nhm.ac.uk/discover/crown-shyness-are-trees-social-distancing.html

https://daily.jstor.org/the-mysteries-of-crown-shyness/

https://www.nationalgeographic.com/science/2020/07/tree-crown-shyness-forest-canopy/

Image courtesy:

Featured image: https://www.nhm.ac.uk/content/dam/nhmwww/discover/crown-shyness/crown-shyness2-full-width.jpg

Figure1:https://www.richardx.co.uk/wp-content/uploads/2019/11/20191103-DJI_0733.jpg

Figure 2: https://www.jasonferrellphotography.com/images/xl/Ascension.jpg