I know there was a thread about it in the past but I didn’t find it.
I can’t remember what the reasoning was. Why are there cages around city trees? What are they protecting? Is it to protect the bark, prevent climbing, prevent animals from urinating on it. What is it?
To prevent damage to the tree, from cars, people, baby strollers, municipal curb grass manicurists, dogs, etc. You’d be surprised how many people scrape a tree when they parallel park in a spot that’s near one.
Usually, especially with young trees, it is to prevent rodents from eating the bark layer around the bottom of the tree during the first few winters. This girdling would kill the tree.
Wait, are we talking about a small-gauge wire mesh fence or are we talking a thicker decorative fence? The small-gauge would be for rodents, but the decorative isn’t going to keep squirrels or rats or mice or anything away from the trunk.
Protecting them from deer is also a big issue in some cities.
Thick decorative iron stuff. This isn’t for rats or even squirrels.
The large cages are mostly to protect from people. A vehicle is still going to run it down. The cages can make a big difference in a tree making it to a large size at which point people are not as likely to break it, bang it, kick it, or or carve it when drunk or bored.
Could be also to keep bicyclists from chaining their rides to them.
Vehicles will do a whole lotta damage to a young tree at once, but even unarmed pedestrians can wreak havoc to trees in much-used environments. Some people (mostly young males) like to kick everything they can. Enough kicks in one place and the tree bark will wear through, offering a route for pathogens to go in and infect the tree. Ripping out diseased / dying park trees and replacing them with healthy ones is very expensive.
When I lived in an inner city neighborhood in Atlanta, small trees without cages were generally cut down or pushed over in the winter by people who would then use them for firewood.