Deciduous Tree Pruning, when practiced by experienced, knowledgeable arborists, can be beneficial to trees. However, pruning might not be helpful, and in fact can be harmful, in a number of scenarios that frequently present themselves.
Deciduous trees should not be pruned in the wrong seasons. During the late Summer/Fall time period, trees are under stress (i.e.: using energy), and should not have live limbs removed (deadwooding is a different story). The other season when trees should not be pruned is the period in the Spring when they are using energy to form new leaves.
Trees should not be pruned if they are under stress from other causes, such as recent storm or construction damage, draught conditions, insect infestation or recent over-pruning, topping, over-fertilizing and other abusive practices.
Old, declining (dying-back) trees should not have live growth removed. Such trees need all the leaves they can produce, and pruning will speed up the rate at which they decline. If an old tree is determined to be a hazard, cabling may constitute a temporary solution; in many cases the tree should be removed (replaced).
Finally, many trees are doing just fine by themselves, and don’t particularly need pruning. Pruning such trees could be seen as a pretty shady practice. (sorry).
Hangin' in Boulder
Every arborist can come up with a similar list of reasons why pruning certain trees is not warranted; what sets tree services apart is whether they abide by such a list. At Berkelhammer Tree Experts, Inc. we make it a point of pride to fit tree pruning into the larger goal of providing sound tree care. Trees should be pruned when and only when they will benefit by it.
So why prune trees? Proper pruning can improve the health, physical strength, longevity and aesthetic appearance of trees. The International Society of Arboriculture, in its pruning standards, defines four basic pruning procedures: Crown cleaning, crown thinning, crown reduction, and crown raising. When performed competently, using proper cuts and in appropriate circumstances, these procedures should achieve some or all of the above goals.
Crown cleaning (see photo at right), which involves removal of dead, broken and hanging branches, is almost always helpful (exception: when storm damage is severe enough that a tree should be removed.) This procedure is especially important for achieving the principal goal of pruning for tree health, that of preventing decay. Cleaning the crown is a relatively simple and inexpensive way to greatly improve the health and appearance of a tree.
Crown Cleaning (deadwood removal)
Crown thinning (see photo at right) is the selective removal of live branches which are weakly attached, interfere with other branches, cross them, or parallel them too closely. Thinning allows greater light penetration into the crown, which improves the health of the remaining branches. Skilled arborists know how to select the eventual “winners” in the quest for light within a tree.
They also understand how to help two branches coexist in circumstances where it’s apparent that the tree needs both. An experienced arborist is always careful not to remove too much live growth in a given year, and can come up with creative ways to effectively thin a tree. This may require a finer focus, in which many small cuts are made instead of several large ones. A careful arborist can “work with” a tree, sometimes over the course of many seasons, to help it a achieve a graceful, sound branching structure. Crown thinning can help a tree achieve such a structure while also helping reveal it to the untrained eye.
Crown Thinning (selective removal)
Crown reduction (see photo at right) involves the cutting-back of the ends of a tree’s outer branches. When done properly, through the technique of light or moderate drop-crotching, crown reduction can significantly reduce the likelihood of major storm damage occurring in a tree, while introducing only insignificant amounts of decay into the wood. Light to moderate crown reduction is a very difficult task for most tree climbers, as it requires one to climb further out along many of the branches, and also to be adept at the use of pole saws and pole clips while stationed in very tenuous positions. Our climbers are competent at these techniques, and use them when required. Please note: Aggressive crown reduction, or “topping”, should never be advised or practiced by any arborist. Don’t top trees!
Crown raising is simply the removal of some of the lowest branches on a tree, and is done for reasons of convenience and/or aesthetics, rather than for health reasons. Excessive raising of the crown can cause a number of problems, and should be avoided.
Experienced arborists understand how trees respond to different pruning approaches. They’ve followed the changes in many particular trees through the seasons and the years, and thereby learned how to care for them, whether through careful pruning, or by choosing not to prune when it could cause harm. Before choosing an arborist to prune your trees, ask him or her to give you the locations of trees he or she has worked with over the years. Trees are precious commodities in the Front Range region, and we need to care for them properly.