Lopping versus Trimming

Lopping versus Trimming. (used with permission QAA)

Lopping is not good for trees, neither is it good for tree keepers. Here is some simple information on what lopping is and why it is bad for trees and the people who own or manage them.

What is lopping?

Lopping is the cutting of stems or branches to “stubs” or to lateral branches that are not large enough to assume their terminal role.

We hear regularly from concerned tree owners that their trees have been lopped, often after they were advised by a “tree lopper” that this would solve a perceived problem: maybe the owner was concerned that the tree has grown too tall to manage or that too many leaves were clogging up their gutters.

The reality is that lopping creates many more problems than it solves. Lopping often removes between 50-100% of a trees’ canopy. As a trees’ foliage is essential for food production, this kind of shock triggers new growth that is added to combat the massive amounts of stress that the tree suffers. This new growth is sometimes called epicormic or reaction growth.

The tree needs to produce a new crop of leaves as soon as possible in order to continue to produce enough food to survive. If a tree does not have stored energy reserves to do this, it may die.

Trees that are stressed are vulnerable to insect and disease infestations, while large, open pruning wounds expose the sapwood and heartwood to decay and fungi.

Lopping makes beautiful trees ugly.

The natural branching structure of a tree is a biological wonder. Lopping removes the ends of branches leaving ugly stubs. Lopping destroys the natural form of a tree.

Lopping is expensive.

If a tree survives, it will require pruning again within a few years i.e. epicormic growth will need to be removed in order to reduce the tree failing. Another cost, not often perceived, is the reduction in property value. Healthy, well maintained trees can add 10-10% to the value of a property. Disfigured, lopped trees are considered an impending or ongoing expense.

Another unseen cost of lopped trees is the potential liability: Lopped trees are prone to failure and can be hazardous: since lopping is considered to be an unacceptable pruning practice (see Australia Standard AS 4373-2007; Pruning of Amenity Trees), any damage caused by branch failure of a lopped tree may lead to a finding of negligence in a court of law.

Lopping may lead to decay.

The preferred location to make a pruning cut is just beyond the branch collar at the branches’ point of attachment. The tree is biologically equipped to occlude this kind of wound over time, provided the tree has sufficient vitality, and the wound is not too large.

A cut made mid-way along a branch or halfway up the stem creates “stubs” with wounds that the tree may not be able to close. Exposed heartwood may begin to decay. Few trees can successfully defend the multiple severe wounds caused by lopping.

Lopping creates hazards.

The survival mechanism that causes a tree to produce epicormic shoots presents further problems. The shoots develop from buds near the surface of the old branches. Unlike normal branches that develop in a socket of overlapping wood tissues, the new shoots are anchored only on the outermost layers of the parent branches.

The new shoots grow very quickly, often as much as 3-4 meters in one year in some species. Unfortunately, the shoots are prone to failure especially during windy conditions.

Ironically, while the goal was to reduce the tree’s height in order to make it safer, lopping has severly increased the risk of failure.

Lopping may lead to sunburn.

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 of which may be sunburn of the tissues beneath the bark. This can lead to the formation of cankers; bark splitting; branch failure and death of some branches.

Tree Loppers are often untrained and not educated in correct pruning techniques; they are therefore not able to make informed decisions about your trees. Tree lopping is often sold as a “quick fix” for tree problems but this creates far more problems than it fixes.

Alternatives to Lopping.

Pruning or canopy reduction of a tree is sometimes unavoidable.

There are recommended techniques for performing this work (see Australia Standard AS 4373-2007; Pruning of Amenity Trees). If a branch must be shortened, it should be cut back to the lateral that is large enough to assume the terminal role. A guideline for this is generally to cut back to a lateral branch that is at least 1/3 the diameter of the limb being removed. This method of branch reduction should ideally retain the natural form of the tree.

Pruning large trees can be dangerous.

If pruning involves working above the ground or using power equipment, you should hire a Qualified Arborist. An Arborist can determine what type of pruning is necessary to improve the health, appearance and safety of your trees.

What services can a Qualified Arborist provide?

Consultation: Advice on everything tree related, from correct planting of recommended species to tree health, structure and stability.

Tree Health Care: Soil amelioration, foliar applications, pest and disease management.

Report Writing: Arborist’s reports for Local Authorities regarding Development Sites (compliant with Australian Standard AS4970-2009 Protection of Trees on Development Sites), Tree safety and/or Impact Assessments.

Pruning: Professional pruning techniques are used to: reduce risk, reduce wind resistance, improve access over roads or to improve the structure of young trees.

Removal: Safe, controlled techniques to remove hazardous or dangerous trees.

Management Plans: Long term plans for long lived plants or pruning and management programs for Body Corporates, Shopping Centres and School.

Qualifications.

As with all trades and professions, there are different levels of qualification for operators and consultants. If you are employing a consultant, they must me qualified to AQF (Australian Qualification Framework) Level 5 Diploma in Horticulture (Arboriculture). If you want a tree removed or pruned professionally, your Arborist must be qualified to the minimum AQF Level 3 in Horticulture (Arboriculture).

When selecting an Arborist, please check that they have:

  • Membership of a professional organisation, such as QAA (Queensland Arboricultural Association).
  • AQF level 3 in Arboriculture (as specified in the Australian Standard referred to above)
  • Proof of a current Public Liability Insurance
  • A list of references from previous clients.

Avoid using the services of a tree a company that:

  • Uses lopping as a technique
  • Uses spikes for any works apart from when a tree is to be removed.