Lopping is perhaps the most harmful tree pruning practice known. Yet, despite more than 25 years of literature and seminars explaining its harmful effects, lopping remains a common practice. This brochure explains briefly why lopping is not an acceptable pruning technique and offers better alternatives.
Lopping is the indiscriminate cutting of tree branches to stubs or lateral branches that are not large enough to assume the terminal role. Other names for lopping include “topping, heading,” “tipping,” “hat-racking,” and “rounding over.”
The most common reason given for lopping is to reduce the size of a tree. Often homeowners feel that their trees have become too large for their property. People fear that tall trees may pose a hazard. Lopping, however, is not a viable method of height reduction and certainly does not reduce the hazard. In fact, lopping will make a tree more hazardous in the long term.
Lopping often removes 50-100% of the leaf-bearing crown of a tree. Since the leaves are the food factories of a tree, this can temporarily starve a tree. The severity of the pruning triggers a sort of survival mechanism. The tree activates latent buds forcing the rapid growth of multiple shoots below each cut. The tree needs to put out a new crop of leaves as soon as possible. If a tree does not have the stored energy reserves to do this, it will be seriously weakened and may die.
A stressed tree is more vulnerable to insect and disease infestations. Large, open pruning wounds expose the sapwood and heartwood to attacks. The tree may lack sufficient energy to chemically defend the wounds against invasion, and some insects are attracted to the chemical signals trees release.
The preferred location to make a pruning cut is just beyond the branch collar at the branch’s point of attachment. The tree is biologically equipped to close such a wound, provided the tree is healthy enough and the wound is not too large. Cuts made along a limb between lateral branches create stubs with wounds that the tree may not be able to close. The exposed wood tissues begin to decay. Normally, a tree will “wall off” or compartmentalize the decaying tissues, but few trees can defend the multiple severe wounds caused by topping. The decay organisms are given a free path to move down through the branches.
Branches within a tree’s crown produce thousands of leaves to absorb sunlight. When the leaves are removed, the remaining branches and trunk are suddenly exposed to high levels of light and heat. The result may be sunburn of the tissues beneath the bark. This can lead to cankers, bark splitting, and death of some branches.
The survival mechanism that causes a tree to produce multiple shoots below each topping cut comes at great expense to the tree. These shoots develop from buds near the surface of the old branches. Unlike normal branches that develop in a socket of overlapping wood tissues, these new shoots are anchored only in the outermost layers of the parent branches. The new shoots grow very quickly, as much as 20 feet in one year, in some species. Unfortunately, the shoots are very prone to breaking, especially during windy conditions. The irony is that while the goal was to reduce the tree’s height to make it safer, it has been made more hazardous than before.
The natural branching structure of a tree is a biological wonder. Trees form a variety of shapes and growth habits, all with the same goal of presenting their leaves to the sun. Lopping removes the ends of the branches, often leaving ugly stubs. Lopping destroys the natural form of a tree.
Without the leaves (up to 6 months of the year in temperate climates) a lopped tree appears disfigured and mutilated. With the leaves, it is a dense ball of foliage, lacking its simple grace. A tree that has been lopped can never fully regain its natural form.
The cost of topping a tree is not limited to what the contractor is paid. If the tree survives, it will require pruning again within a few years. It will either need to be reduced again or storm damage will have to be cleaned up. If the tree dies, it will have to be removed.
Lopping is a high maintenance pruning practice, and there are some hidden costs of lopping. One is the reduction in property value. Healthy, well maintained trees can add 10-20% to the value of a property. Disfigured, lopped trees are considered an impending expense. Another potential cost of lopped trees is the potential liability.
Lopped trees are prone to breaking and can be hazardous. Since lopping is considered to be an unacceptable pruning practice, any damage caused by branch failure of a lopped tree may lead to a finding of negligence in a court of law.
There are times when a tree must be reduced in height or spread. Providing clearance for utility lines is an example. There are recommended techniques for doing this. If practical, branches should be removed back to their point of origin. If a branch must be shortened, it should be cut back to a lateral that is large enough to assume the terminal role. A rule of thumb for this is to cut back to a lateral that is at least 1/3 the diameter of the limb being removed.
This method of branch reduction helps to preserve the natural form of the tree. However, if large cuts are involved, the tree may not be able to close over and compartmentalize the wounds. Sometimes the best solution is to remove the tree and replace it with a species that is more appropriate for the site.
Pruning large trees can be dangerous. If pruning involves working above the ground or using power equipment, it is best to hire a professional arborist. An arborist can determine what type of pruning is necessary to improve the health, appearance, and safety of your trees. A professional arborist can provide the services of a trained crew, with all of the required safety equipment and liability insurance.
There are a variety of things to consider when selecting an arborist:
– Membership in professional organizations such as the Arboriculture Australia, or the Victorian Tree Industry Organisation (VTIO).
– Proof of insurance.
– A list of references (Don’t hesitate to check.)
– Avoid using the services of any tree company that:
– Advertises lopping or topping as a service provided. Knowledgeable arborists know that lopping is harmful to trees and is not an accepted practice.
– Uses tree climbing spikes to climb trees that are being pruned. Climbing spikes can damage trees, and their use should be limited to trees that are being removed.
The team at Total Tree Care are trained in the latest arboricultural techniques and fully equipped to give your trees the best, long term results that will address your tree related concerns.
Our team are ready to take your call.