I think that it dpends on the species. Certain vigerous types can be "Hard Pruned" taking off more then 25%. It also depends on the age of the tree and over all health. If you take a tree that has been slowly getting by ( from being in the wrong hardiness zone or poor soil conditions ect..). Then you come along and over prune it the tree may have a hard time recovering. It is good question though. To bad for us were not here long enough to see some of the results we have on trees. When you prune a 80 year old tree it would be nice to see it again when its 180yrs.old. Butchers beware!!!!!!! You will be brought out into the light. Time will show your work as fraud. The trees dont lie.
