The canopies of some trees don't ever touch each other. It's a phenomenon called Crown Shyness.
Less than 100 years ago, back in 1920, a botanical phenomenon that gave us beautiful and impressive images of certain forests was observed for the first time. In 1955, the botanist Maxwell R. Jacobs described this phenomenon as “crown shyness” after studying various populations of eucalyptus. The crown shyness is also known as canopy disengagement, canopy shyness, or intercrown spacing.
This phenomenon consists of limited growth of the canopy of the trees, in such a way that the leaves and branches of adjacent trees do not touch each other. This produces figures and patterns with the sky in the background when the trees are observed from the ground.
Crown shyness has been observed in certain European oak and pine species and tropical and subtropical species, such as some eucalyptus, species of the Dryobalanops genus, Pinus contorta, Avicennia germinans, Didymopanax pittieri, Clusia alata, Celtis spinosa, Pterocymbium beccarii, Picea sitchensis and Larix kaempferi.
The scientific community has not yet reached a consensus that explains the mechanism that gives rise to this phenomenon.