A Brief Introduction to Tree Work Terminology and Definitions

Tree pruning is one of the most important aspects of tree maintenance and upkeep. Pruning keeps a tree in a safe condition, by removing dead or crossed branches, promoting strong future growth. It is also paramount in regulating the overall size of the tree, and the quality of the flowers and/or fruit that it produces.

Of course, as important as tree pruning is, when done incorrectly or too frequently, it can spell disaster for your tree. Improper pruning can lead to trees becoming diseased, unstable, and aesthetically unappealing.

Why is it so important to understand basic tree work terminology?

You must understand some of the basic terms that are most commonly used in tree work so that you can ensure that you end up paying for the appropriate service. Something as simple as mixing tree lopping and tree pruning up can be disastrous. But it also helps to understand what your arborist is recommending.

For example, crown thinning will not reduce the height of your tree, which is a common misconception, and neither will a crown lift. A basic understanding can help you to secure the services that you want, absent any mistakes.

What are the three main tree pruning options and how are they different?

Below we are going to list the three main pruning services offered by arborists:

Crown Thinning

Crown thinning is essentially the removal of a portion of the smaller branches at the outer crown of the tree, to create a more uniform density of foliage around an evenly spaced branch structure. This tidying up of the crown is typically confined to the more broad-leaved species of tree.

Crown thinning doesn’t reduce the overall size or shape of the tree, but it can certainly help to tidy it up. The main purpose of crown thinning is to ultimately allow more sunlight through to the lower levels of the tree. It is also helpful for reducing wind resistance, weight, and for keeping trees that are known to produce significant ‘epicormic’ growths in check.

As a word of caution, you should be careful not to have more than 30% of the tree’s canopy removed in one sitting. This can cause serious trauma to the tree. Give it time to recover. If you are unsure, seek professional guidance before going ahead with this.

Crown Lifting (or Raising)

Crown lifting as the name suggests is the removal of the lowest branches. Proper practices dictate that crown lifting should not include the removal of large branches that are growing directly from the trunk, as this can cause large wounds that may grow extensively decayed, thus leading to dangerous long term issues (or short term biomechanical instability).

To be honest, crown lifting on mature trees should be avoided if possible. If not, at least ensure that the branches that are removed are strictly secondary. Otherwise, you can shorten the primary branches.

Crown lifting is effective for increasing light transmission to the lower rungs of the tree. Crown lifting should be specified with a certain height or fixed point in mind, to ensure that the right amount is removed, and no more than the recommended amount.

Crown Reduction

Crown reduction is the reduction of the height (or spread of the crown) of a tree. Crown reduction can be used to reduce the amount of mechanical stress on the various individual branches, or the entire tree itself. This process can make the tree better suited to its environment, by reducing the effects of shading and light loss.

The result of crown reduction should be to maintain the inner frameworks of the crown, and thus a significant amount of the leaf-bearing structure should be left.

When making crown reduction cuts, they must be as small as possible, and as a general rule of thumb, should not exceed 100mm in diameter (unless of course, it is necessary to do so for the tree’s health).

Not all species of trees are suitable for crown reduction. It should also not be confused with crown ‘topping’, as it can be an incredibly harmful treatment for the tree.

Why is it so important to make the correct cuts when pruning?

The fact is, whenever you cut the tree while pruning, you are effectively wounding the tree. The ability of a tree to withstand the wound and maintain a healthy growth pattern will be greatly impacted by the overall size, angle, and position of the cut.

As a rule of thumb, branches should be removed at the point of their attachment, or shortened to a lateral that is at least 1/3 of the diameter of the removed portion of the branch itself. All of the cuts should be kept as small as possible, to inflict as little trauma on the tree as is necessary.

Pruning is kindness when done properly. You can think of it as removing a child’s tonsils if they keep repeatedly getting poorly. You see, when left to their own devices, often trees can grow crossed and malformed branches or end up with various diseases. This is why a qualified arborist needs to come in and make the necessary changes, promote strong future growth, and keep the tree looking happy and healthy.

A word of caution for those looking to have their trees pruned

Be mindful of the fact that many trees are legally protected. Thus felling, or even pruning a protected tree without permission from your local planning authority may be deemed as a criminal offence.

Be sure to check for any tree preservation orders, or conservation area restrictions with your local council, before carrying out any work.

If you are unsure about the species of a tree in your garden, or you don’t know if it is protected, contact your local arborist and consult their expertise.