When I was a boy we always seemed to be climbing trees. It was so prevalent that you couldn't pass a tree of any size without spotting a boy somewhere in it. I use the term boy as I can't for the life of me remember that any girls ever went in for the activity.
As far as I can remember, no-one ever fell out of a tree and we didn't damage them - we were fond of the great beasts and considered them to be part of our environment. On returning to an area I knew as I child some years ago, all the buildings had gone, but I recognized some of the trees I had climbed. They were like old friends.
I don't think I've seen a boy in a tree in several decades, and that's a shame. Maybe the trees are glad but it speaks of how our society has changed. For instance, any injury incurred would result in some lawsuit against the owner, be it park, city or private. So any likely looking boy would be chased off.
But then they're all sitting down playing Nintendo, or searching Facebook. Somehow I think my childhood was better.