Crown Shyness

The fact that trees do not rub on each other is known as "crown shyness." Google Scholar lists about 200 scientific journal articles using the term "crown shyness":

http://scholar.google.com/scholar?as_sdt=1,49&q=%22crown+shyness%22&hl=en&as_vis=1

A nice little literature. One abstract says the issue was first identified in the 1920s, making it almost 100 years old. Cool! The prevailing theory seems to be that the trees touch when the wind blows so stop growing, although this is questioned and crown shyness is often termed a mystery. 

So this is a known issue. However, what I observe is much more complex than a "crown shyness" where the branches simply stop growing. They change direction and keep growing, forming intricate avoidance structures.