LOL Walter. I have asked this question on a few forums as I was having trouble getting answer. It seems it may be the slow growing Pines (white pine?) that people are most fearfull of taking too much off! That is why I found Jerry's anwer making the most sense so far!
I guess you include all pines from your answer but maybe you can clarify?
I hope Jerry Merslik doesn't mind me quoting his best guess from a thread at Bonsai Vault!
Hi Brett,
You asked about why pines can't be pruned as hard as other trees?
Simply, I don't know the answer.
In my reading and guessing, the evolution of pines is that they have grown and adapted mainly to areas where deciduous trees can't easily grow. In these areas of dryness or high heat or extreme cold or extreme wind they survive by being economical in their growth. Most survive these tough conditions by being slow growers in their environments although a few given the right conditions can grow amazingly fast for a period of time. They do not waste energy by making and losing leaves on a yearly basis but economize by keeping needles for a number of years.
Their basic physiology is such that they do not carry the reserves or even the latent buds to allow recovery from severe attacks. They survive but do so without much excess in their recuperative powers.
How is that for a pure guess?
Jerry