Trees that don't touch

Crown shyness is a phenomenon observed in some tree species, in which the crowns of fully stocked trees do not touch each other, forming a canopy with channel-like gaps. The phenomenon is most prevalent among trees of the same species, but also occurs between trees of different species.

The next time you're out walking through the forest, take a moment to look above you at the beautiful trees, and you might be pleasantly surprised by what you find.

The naturally occurring phenomenon is called "crown shyness" because the uppermost branches of certain tree species don't like to touch one another. The intriguing behavior was first observed in the 1920s, and various hypotheses have been presented since then in an attempt to explain it. Some believe it occurs to reduce the spread of harmful insects. Others 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 to maximize the process of photosynthesis which is done by the tree leaves. Despite these various theories, however, nobody knows for sure why this phenomenon occurs, but it serves to remind us of just how beautiful nature can be.

Where it happens

Crown shyness occurs with many species of trees, such as black mangrove trees, camphor trees, eucalyptus, Sitka spruce and Japanese larch. Intercrown spacing can happen between different species, the same species or even within the same tree. You can see this intercrown spacing in action in the video above.

Crown shyness doesn't happen all the time, and it can occur in any forest.

You're more likely to see crown shyness in a tropical forest, which tend to have flatter canopies, according to Venerable Trees.

The Smithsonian describes crown shyness as "a giant, backlit jigsaw puzzle. A thin, bright outline of light isolates each tree from the others."

It helps to think of each tree as an individual island in the forest, says Steve Yanoviak, a researcher at the Smithsonian Tropical Research Institute in Panama. These "islands" are still connected via a network of woody vines known as lianas that act like telephone lines.

Generally, bigger islands have more species than smaller islands. Yanoviak's research shows the same is true in trees.