
It depends entirely on how far around the trunk the damage went. Under roughly a third of the circumference and the tree generally recovers on its own with no intervention at all. Between about half and two-thirds it is a genuine maybe, worth a season of watching. All the way around and it is finished — a fully girdled young tree cannot be saved, and repair grafting is a specialist technique that is not economic on a landscape tree. Do not wrap the wound, do not paint it, and do not tape the bark strips back into place; removing loose flapping bark is the whole of the first aid. The real work is prevention: a rigid trunk guard or a ring of fencing standing off from the trunk, installed before the next fall, is the only thing that reliably stops a repeat.
Nothing here is a safety hazard — a two-inch sapling is not going to injure anyone, and there is no reason to rush a crew out. The clock that matters is biological and runs over one to two growing seasons: a girdled tree can leaf out looking perfectly healthy the following spring on stored energy and then collapse in midsummer, so surviving one spring is not proof of survival. The second clock is the calendar. Protection has to be in place before the next fall, because a tree rubbed once is likely to be rubbed again, and that repetition is what converts a survivable one-sided wound into a fatal ring.