I hate to be a spoilsport.....
....but the comment about public lands is right on. What people do on their own land is their business, but a lot of resources, goodwill and money can get lost by shooting up trees. Target stands are easy to build: nailing a target to a tree is right up their with sticking it on a metal sign, Ralphie. And hitting bullets with saws and milling tools is no fun.
Now I have to confess that I've done it to trees on our range that were already so bullet ridden I did not want to damage a chain or blade. I also knew a dendrologist who collected samples of nuts and cones with a shotgun.
I am also not adverse to cutting up 4x4s and such that serve as targets. It makes for a good race between relays to see who can cut their post first, and I dont have to inventory a lot of excess ammo afterwards.