|the trees in my backyard need to be cleaned out. is there a certain|
|I'm afraid the answer depends upon the type and size of the tree. Generally you can completely remove limbs, back to the branch collar, when you are thinning the canopy, but you won't want to remove more than about a third of the limbs of your tree (regardless of size). If you'd like to read a little about pruning trees and see some line drawings to help you decide the best approach, here's a publication from the University of Florida to download: http://edis.ifas.ufl.edu/mg087
I hope it offers some helpful tips.