• Treelands NZ

Why topping trees is bad, can cost you money, and be unsafe!

Updated: Jul 20

As Arborists, we often get asked if we can top a tree and our answer is “NO”. But why is this? The main reasons are:

  1. It’s detrimental to the tree's health and creates a safety issue.

  2. It will create a bigger problem and cost down the line.

  3. It’s bad arboricultural practice.


What is topping?

Topping refers to a pruning technique which removes large amounts of a tree's crown, usually more than 30%, often close to 50% or more. See the photos below for a example.


Photos from "crimes against treemanity" Facebook group


Why is it bad for the tree's health?

Topping a tree often drastically reduces its lifespan. The tree cannot recover from the large pruning wounds, and will slowly decay at these points. The tree will either die, or respond by growing lots of vigorous shoots, often around the pruning wounds, or from the trunk and branches of the whole tree. Further down the track, as decay sets in at the topping points, there is little wood left for the shoots (which are now large branches) to be supported by. This can cause a hugely dangerous situation as they begin to fail. Once topped, a tree will never be the same again, the structure is ruined and it can take decades to correct bad pruning in a large tree.


Why does it create a bigger problem and cost down the line?

As well as the safety issue already highlighted, the vigorous shoots that form because of the topping, will grow at a faster rate than if the tree hadn't been pruned or was pruned correctly. This growth response is a reaction to losing large amounts of canopy. Meaning, that the tree might well get bigger, faster with more dense unstable branches, causing the original problem to be worse than it was before. So you may well end up having to pay to have the tree pruned again or even removed.


Why is bad arboricultural practice?

Because of bad health implications to the tree, safety issues it can create and causing further cost and issue down the line, it is not recommended by professional, qualified Arborists to top trees. An Arborist will recommend that the tree gets “reduced”.


What can you do to make your tree smaller?

To make your tree small/have less mass, you can carry out a reduction. Canopy reduction involves pruning small to medium sized portions of the canopy extremities, whilst retaining a suitable growth point on the branch/es which are being pruned back. The amount which can be removed without detriment to the tree varies based on not only species, but also each individual tree, but will be no more than 30% of the tree's crown. The aim is to achieve a tree which has a similar or improved form, but slightly smaller. This technique is also used to reduce wind loading, subsequent loss of limbs or portions of the tree. If you want a tree which is half of the size of your current one, that tree is probably not the ideal species for the site. View the clip below for a great example of one of our reduction to a London Plane



Are there exceptions?

Yes, but it is a management option used by Arborists in very specific cases. A heavy reduction can be used to stabilise large old trees, or trees with major defects. In this case, it is the lesser of two evils, but will allow you to retain the tree.


Conclusion

In summary, “topping” of a tree should not be done. It creates health issues for the tree, safety problems and may well cost you more money down the line. Instead of topping a tree, a reduction should be carried out as this will have less impact on the tree's health, the regrowth will be slower(meaning your tree stays smaller for longer),it won't create safety issues, and means you won't have to prune your tree so often therefore costing less.


Above our examples of correct reduction pruning from "Treelands before and after album" on the Treelands facebook page


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