How to prune trees with bad structure?

[Poda Girona]

Hi,

I am an arborist from Spain. Arboriculture is not at a high level in some parts of Spain. I regularly see trees with a very poor structure in cities. On the photo below there is an example of many city-trees in my area.

What is your opinion on these trees and how would you prune them?!

gracias,
Koert

 

[sgreanbeans]

Those trees didn't have bad structure, they had bad pruning. Trees like that need to be left alone. Let the epi's grow and select the ones with good attachments to stay and develop into branches. You can restore structure, but it takes a long time.....several years. Those trees have been topped and then maintained by "lift and gut" city peeps or contractors with a ordinance dictating what has to be done. Cleared for pedestrian traffic and vehicles. No proper pruning there. Urban trees planted in those areas are planted with good intent. Going Green is trendy. Then those darn trees go and do something stupid, they get bigger. And we cant have that can we. So city bubs, in power, who really don't give a chit about the trees other that the "Tree City USA" designation, but other than that, they hate them, they get complaints, lawsuits, they cost a bunch to maintain thousands of street trees, so in general, they are considered a nuisance to them. So the need for proper care is listened to, but never really considered, as that would mean letting them get big and have a structure that would interfere with lights, buses, peeps and mess up sidewalks and a huge list of other problems. They are great until they get a little size to them, after they do, they often get abused like that. They are usually planted in mass quantity's, by volunteers, watered once and then forgotten about until they are a problem with the size or they die from improper planting. Then they are so outa control its hard to get them back into shape, it can be done, but that means the city has to pay, and that is where it goes wrong. It takes little time to do that, pictured there, and a bunch of time to do it right. The city does not want to spend any money on trees, but know they have to, so it is the bare minimum and the lowest bid........most of the time. I was responsible for downtown San Diego, most of it anyways and it was a total nightmare. Those poor trees just don't have a chance once they get a little size to them. When given parameters like this: Up 8ft over the sidewalk,14ft over the street, don't block any signs, lights or corners, nothing over the benches, nothing within 3ft of any line, 10ft from the trolley lines, 5ft away from any building, keep them below the windows for beach views...etc, You cant really have a nice structured tree. Too often, if not most of the time, they are always planted 2 close and have no soil to speak of and are planted in areas that they should never be. I have seen trees completely cooked on one side because of a reflection off a building. I have also seen decent sized trees shaped like lolly pops with a hedge trimmer We try to manage urban trees in cityscapes, but sometimes it is pretty futile. Good luck with your job, its not a easy one. You will never please everyone. No matter the shape or condition of the street trees in a big city, someone always has a problem with them. Branch blocks view, dropped a 6" long twig on my car, drops too many leaves, has seeds! It never stops. Some of the people that you try to educate will walk away with a change of heart and a different outlook when it comes to the trees, but most won't/don't care and just want it their way, period. I had the idea of up potting 16' box into a 36" and dropping them into the wells, keeping them in there until too big for the box and need to be up potted again, pop them out, and instead, do it again and replace them with the smaller "beginners" in 16"s and plant the old one's in the parks or general common areas through out the city, where they would have space and soil, then do it all over again when the next batch gets to big for the box, say 4-7 years. This Would save lots of money, the trees would never be a issue to anyone and they will always stall small, reducing the city's liability, keep their recognition for being green and keeping most of the folks happy. But again, you will never have that 100%. Someone will complain about city tree shading out there precious tomato plant, on their balcony and want it topped, lifted and gutted or removed altogether and loud squeaky wheels get greased.

 

[beastmaster]

City and commercial trees don't have a chance. Everyone loves a tree intail its blocking their view or their store's sign. Lots of the time there are legitimate safety issues that have to be addressed and leads to the mauling of a tree. But most of the time the main root of the problem is poor tree selection by the powers that be. People outside the industry have trouble thinking in tree. No one today seems to be able to foresee what a tree is going to look like or how big it'll be in 20, 40, or 100 + years.
In this day and age we can find a tree to suit every kind of sight for the most part. So why do city planners, and landscape contractors keep planting Liquid Ambers under power lines, or Ficus next to side walks..
Lot of the problem is people think of trees as disposable assets. Their full life span isn't addressed if thought of at all. They get to big some pencil pusher calls someone to "Fix them".
The street trees in the pictures have been topped and headed back at some point in their life. But considering the abuse it looks like some one has tried to make the best of a bad situation and rehabilitate them back into trees. To little to late? More then likely. Those trees will start developing problems if they haven't started already from having an un-natural, altered structure. At some point they'll have to be removed, and then an equally unsuited tree will be planted in their place, and the cycle will continue.
There is a simple answer to prevent these problems, hire professional Arborist to handle those things that concern trees, and not some landscape contractor who choses what tree goes where based on nursery prices.
The right tree for the local, early on structural pruning and management while the trees still young, is all it would take and would save millions if not billions of dollars.
I am very prejudice, once a tree has been butchered it'll never regain its natural treeness again. There are lots of things you can do to rehabilitate a hammered tree, but with few exceptions itll never be the tree it could of been.

 

[BC WetCoast]

I have a slightly different opinion from my esteemed colleagues.

These trees provide value to the urban landscape and I would suspect that any attempt to remove them due to any other factor than safety would be met with significant public outrage. Having said that, most municipal arborists realize that the growing site, pruning style and extent will greatly reduce the lifespan of the trees. These needs to be budgeted for future replacements, just like water mains or sewer pipes have to be replaced in a regular schedule (regular schedule can be range from yearly to 100 years depending on the piece of infrastructure - and street trees are just another piece of municipal infrastructure).

In my opinion the trees in the second picture look reasonably pruned. The crotches and junctions are wide and secure, reducing the risk of codom failure. There is foliage for the length of the condoms, which will ensure growth along the entire length of the codom, thereby increasing taper and lowering risk of failure.

In the first picture, the trees have been raised and gutted. The problem I see is all the tight crotches at the old topping cuts. I would be pretty confident there are junctions with included bark that would be susceptible to failure. I'm sure the local population thinks these trees look beautiful. So someone needs to make a policy decision. Maintain the current pruning style/method knowing that the lifespan of the tree will be shortened, or change the pruning style to lengthen the lifespan.

I suspect these trees are on a short pruning cycle (number of years between prunings) and if the decision was to lengthen the lifespan, I would begin by removing some of the tight crotch codoms, subordinate others to create a number of dominant codoms. This could be done over a number of pruning cycles.