Improper tree pruning can have unwanted results. These trees were topped about 3 years ago. Over 80% of their foliage was removed at that time. Surprisingly, one of the trees still has foliage, the other two are not doing well. What happened?
Whenever you prune a tree, it will respond with new growth. The tree will use its stored energy reserves to produce growth. It senses that it needs more leaves to make up for the loss food (carbohydrates from photosynthesis) production for survival. The tree has only so much energy reserves. Removing a vast amount of foliage at one time can send it into shock. Immediately, new growth will occur as the tree tries to recover from the loss of photosynthesis. The middle tree above has no new shoots, it has only a cluster of leaves around the middle. The tree on the left shows a reduction of growth too, but probably not enough to sustain it for long. The trees here will probably not be able to sustain any new growth, they have used up their stored energy reserves. I don't know what the property owner had in mind when the trees got topped. Was it the art? Or maybe shade reduction? If the owner was looking for premature tree death, then why not cut the tree completely down?
Here is another example of excessive pruning. The tree on the right in front of the palm has been pruned leaving only a large number of leaves on the top of the tree. The owner may have wanted to let some light into the house. Bur now all the weight of the tree is at its top. In the wind the mass of leaves becomes a large sail whipping the tree around. A strong wind can break the tree. The palm tree is fine its structure allows it to be flexible in the wind. The leaves of the palm allow much of the wind to flow through it freely. The trees on the left side street have been pollarded (a little different than topping). There are no leaves left to produce energy for the trees. Again, the tree needs to rely on its stored energy to respond. New growth will appear on the tops of the cuts. The trees will send out energy to produce numerous shoots on each stub. These new shoots will be long and about ½ -!” wide with lots of leaves. The branches will have weak connections and have to be re-cut at least every other year.
When pruning a mature tree or any tree for that matter, do your homework, and ask the question of: “Why are you pruning? “ Consult an arborist and visit a tree nursery website.
Trees need leaves to survive. Never remove more than 25 – 30% of a tree's foliage at any one pruning session. Don't prune for tree failure.
Pollarding -” Pollarding is a pruning system involving the removal pf the upper branches of a tree which promotes the growth pf a dense head of foliage and branches.” Wikipedia