Tree pruning, tree cutting, tree surgery, tree trimming –whatever terminology is used, it all involves removing branches from the crown of a tree.  Tree pruning is a necessary part of tree maintenance in the urban environment.  There should always be a compelling reason for each branch that is pruned from a tree.  Live branches should never be removed unnecessarily.

       Tree branches perform several important functions for the tree.  Chief among these is the production of energy, sometimes known as tree food.  Since photosynthesis produces the carbohydrates and sugars that ‘feed’ the tree, removing live branches without good cause may adversely affect the health of the tree.

       There are reasonable objectives that an arborist mayh have in mind when pruning trees that often include one or more of the following:  Removing deadwood; removing crossing, rubbing, broken, diseased or dying branches; cutting branches back from buildings, sidewalks, roads and other impediments; opening up vistas; and elevating or removing lower branches to allow room for walking under the tree.  Sometimes live and healthy branches are partially or entirely removed to maintain the shape or structure of the tree.

       Once the decision has been made to remove a branch, the technique used by the arborist will be determined by factors that may include size, location in relation to its proximity to targets, and other considerations.  Whatever the technique, the final result must leave the cambium layer intact so the wound can close over.

       Tree wounds do not ‘heal’ the way we humans do.  The affected tissue is compartmentalized (blocked off) chemically from the rest of the tree and the cambium layer grows on the outside to close it over.  You’ve probably noticed donut shaped rings slowly growing over open pruning wounds.

       The pruning cuts must be made carefully to avoid either cutting off the cambium layer with a flush cut, or conversely, leaving too much wood (stub cut).   Either case can cause decay to enter through the wound into the interior of the tree.    Larger branches often involve several cuts to avoid the weight of the branch from ‘ripping’ down the trunk, leaving an ugly open wound or tear in the bark that may not close over. 

       The firstpruning cut is made on the underside of the branch partially through it at about a foot or so from where the final cut will be.  The second cut will be just outside the first cut, but from the top.  This cut will go all the way through the branch, removing most of it.  Now most of the weight of the branch has been removed, allowing for the final cut to be made.  What is left at this point is a stub about a foot long or so. The final cut is made at an angle, just outside, but not touching the cambium layer.

       Proper tree pruning technique is vital for the overall health and structure of the tree.

              Proper tree pruning technique is vital for the overall health and structure of the tree.  Improper tree pruning can result in tree wounds thatmay permanently disfigure and structurally harm the tree, as well as give an opening for decay, disease and pest problems.