This is not another article about how social distancing will flatten the curve. It’s not a plea for you to stay home. We trust our readers have the good sense to do so.
Instead, this is an article about crown shyness. A fascinating story of how some trees got this whole social distancing thing right, way before we did.
Crown shyness is also known as canopy shyness, canopy disengagement, or inter-crown spacing among other terms. It is a natural phenomenon where the crown (the uppermost branches or top of a tree) tend to avoid each other and not touch. This creates cracks in the canopy akin to a beautiful back-lit jigsaw puzzle in the sky when viewed from below. Since it was first observed back in the 1920s, several scientific studies have been conducted, putting forward a handful of hypotheses in an attempt to explain this intriguing behaviour.
Hypothesis 1: To optimize light exposure
It is a well-known fact that trees grow in the direction of light for the purpose of photosynthesis and tend to avoid shade for the same reason. This is possible due to light-sensitive proteins called photoreceptors, especially found on the leaves and stems of a tree. Photoreceptors sense light, shade, and therefore the proximity of neighbouring trees, inhibiting growth in that direction. Some scientists also theorise that this behaviour allows light to shine through the canopy to reach flora and fauna on the forest floors.
Hypothesis 2: To minimize branch casualty
You’ve seen broken branches on the floor, you’ve probably stepped on a few as well. Branches of trees often suffer physical damage from abrasions and collisions with each other, especially when there are strong winds. Crown shyness could therefore be a coping mechanism that trees employ to reduce the likelihood of branches colliding and breaking off, hence safeguarding their own health.
Hypothesis 3: Prevent spread of harmful insects and pathogens
Last but not least – and most relatable to us right now – would be the situation of pathogen spreading. If one tree has become infected with a viral, bacterial, or fungal infection, then the spread can be halted or reduced without a physical bridge to get to the next tree. The same would happen in the event of an outbreak of harmful pests like leaf-eating larvae and many other creepy crawlies.
For now, the mystery of crown shyness remains unsolved. It could be just one or a hefty combination of many proposed hypotheses that has led to what seems to be convergent evolution among certain species of trees. If you would like to see this striking spectacle of nature with your very own eyes, take a leisurely stroll through our parks and nature reserves while maintaining a safe social distance from fellow nature enthusiasts. Because remember: if trees can do it, so can you!
Written by Genevieve Teo
Illustrated by Lee Ai Cing