Topping Trees Is Bad
To top a tree essentially means to aggressively remove the upper portion of the tree causing permanent harm to its structure. As an Arborist I get this request frequently. Recently I came across a failed Poplar tree that I think perfectly illustrates why you should not top trees. It exhibits the long term effects and the chain reaction of a topped tree.
Let’s examine and break down what’s going on in this tree and what led to the failure.
TOPPING POINT
This stem is where the tree initially was topped. In this particular case it was actually blown out by strong winds but the effect would have been the same if it was manually cut.
DEAD LEAD
This stem was the dominant lead or main trunk of the tree prior to it being topped. Due to its wound the remaining trunk decayed back to the next growth node down, the main union (decayed union).
FAILED STEM
This was the current dominant stem of the tree before its failure.
The original dead stem and this failed stem were likely somewhat similar in size earlier on in the trees life, both fighting to be the dominant leading trunk of the tree. When the dominant lead had its top removed, our failed stem then became the dominant lead. Without having to compete with its neighbouring branch it quickly put on weight and size. Poplars grow fast.
DECAYED UNION
This growth node, where numerous stems formed was the main union of the tree and as a result of the die back from the topped dead lead, decay has spread down and compromised its holding wood, severely weakening it.
Over time, the wood fibers began to further diminish through decay and ultimately led to the tree failing.
REMAINING STEMS
Interestingly enough, we can now see the two remaining stems which are growing at the weakened main decaying union, one of which will become the new dominant lead of the tree. You could probably guess where this is going, the cycle of failure will repeat itself in this tree.
This is why topping trees is not recommended, you get short term gains in return for long haul problems. Topping trees weakens structure and leads to poor branch development. Ironically, people often top their trees for the sake of safety.
HOW COULD THIS OUTCOME HAVE BEEN AVOIDED?
Maintenance early on in this trees life could have have prevented its demise. Through pruning, by reducing the appropriate stems and creating an even canopy with a strong dominant stem this Poplar tree would not have failed to begin with.
IS THERE EVER A TIME WHEN TOPPING TREES IS ACCEPTABLE?
The only reason a tree should ever be topped is hazard mitigation. For example, if the Poplar tree mentioned above was to be retained, it will require continual topping so as to not allow the portion of the tree above the decaying union to get too heavy and once again fail. This is not very cost effective and reflects another reason not to top your trees. Topped trees will require more maintenance as compared to correctly pruned trees.
It is important to understand that not all tree species will tolerate being topped to begin with. Some trees will end up dying shortly afterward due to shock. Topping creates a tremendous amount of stress for any tree to handle. It substantially reduces its energy producing capacity. Trees that do survive will be left permanently disfigured with canopies prone to fungal infection, pests and sun scalding.
I’VE HEARD ABOUT POLLARDING, IS IT THE SAME AS TOPPING?
The short answer is no. Pollarding trees is a pruning technique that is generally used to control the size of trees as well as to promote growth for harvesting purposes and it begins very early on in a trees life. Pollarding requires extensive knowledge of tree biology and an understanding of specific species. Not all trees will tolerate pollarding. Old mature trees are not good candidates for pollarding.
SO HOW DO I CONTROL THE SIZE OF MY TREE?
It’s worth mentioning tall trees are not inherently hazardous. Many home owners are frightened of trees being too tall. Always contact a qualified Arborist for a tree risk assessment. Through appropriate canopy weight reductions, competent pruning and a long term maintenance plan, your trees can be made safe without having to top them and while preserving their natural beauty and structure.
IN SUMMARY, WHY IS TOPPING TREES BAD?
- Shocks the tree, making it more susceptible to disease.
- Creates decay.
- Increases maintenance costs.
- Creates new weakly attached growth susceptible to failures.
- Could kill your tree.
- Ruins the natural aesthetic.
Hopefully you now have a better understanding of why trees should not be topped. We’d love to hear from you. If you need help with your tree maintenance or have any questions regarding tree health or safety, please contact us.
