I use the term loosely. Okay, so maybe I use it mockingly in this context. This sort of thing really should have no connection to the works of Calder, Rodin or Brancusi. It might be worthy of a few fancy adjectives, such as ‘severe’, ‘unusual’, ‘dramatic’ and ‘bold’. Horticulturally though, we might be thinking more like ‘disgraceful’, ‘abhorrent’, ‘ridiculous’ or ‘just plain sad’.
There is nothing wrong with pollarding, that severe sort of pruning that almost all other arborists will tell you is wrong. It involves pruning trees back to the same distended terminal knuckles every winter. Only a few trees are adaptable to the technique, and technically, sweetgum happens to be one of those few trees.
The stipulation is that once pollarded, they MUST be cut back to the same knuckles EVERY winter. A small stub or maybe two can be left on knuckles to allow them to elongate a bit annually, but that is about all. Pollarding is severely disfiguring, and ruins structurally integrity for all growth after the first growing season. Without this annual and aggressive maintenance, pollarded trees are very likely to drop limbs and possibly disintegrate faster than they can recover.
Sweetgums are not often pollarded because they are usually grown for their autumn color. Secondary growth that develops in response to pollarding is too vigorous to color well. The foliage stays green well into winter, and then falls without much color at all. Pollarding sort of defeats the purpose of growing a sweetgum.
The real problem with this particular tree is that it was not pollarded correctly. For one, it was probably cut like this because someone thought that it was too big. It should have been cut much lower if someone was going to put the work into pollarding it at all. Now, the secondary growth that must be pruned away will be very high, and take much more work to prune away. It will also be more exposed to wind. Limbs that break away will fall from higher up, so will fall farther away, and with more inertia.
Secondly, the pruning technique really was ‘abhorrent’. Small stubs are acceptable on established knuckles in order to direct growth. Long stubs that are expected to develop into knuckles are also acceptable. The weird stubs on the trunks of this tree are both too short and too stout. Because they are too short, they will be too shaded to develop into knuckles. They are too stout to compartmentalize or ‘heal’ (if they do not form knuckles) so are likely to decay, and spread decay into the trunks.
Thirdly, this tree was pollarded in summer, which is why the secondary growth is so stunted and underdeveloped now that the tree should be going dormant for autumn. The stunting should not be much of problem, since new growth should develop in spring. The problem is that the lightly colored bark likely scaled when it suddenly became exposed to sunlight by the removal of all of the foliage in the middle of summer. The scalded areas will eventually decay and become open wounds, which will spread decay into the main trunks and limbs. Even if secondary growth is healthy, and the tree gets pollarded correctly every winter, the limbs will eventually become unable to support the weight of healthy foliage.
This is one of the many reasons it is so important to procure the services of a qualifies arborist. Someone payed a significant amount of money to get this valuable tree ruined, and will eventually need to pay more money to have it removed. It would have been much less expensive to pay a bit more to get the tree pruned properly, or to have it removed completely.