And here's where the "fed up" in me wants harsher judgement. He wanted to harm the public, so let his name be public; it's clearly the attention he wanted, so give it to him, and let him feel it. Hopefully for him, it'll be as fun as chopping down that tree.
I don't know who of you has ever chopped down a tree, but it requires a level of planning and pre-thought that can't be dismissed as adolescent impulse. I WANT him to forever be that guy that chopped down an historic tree for lolz so that as age distances him from this "grand" idea, he's able to appreciate it for how stupid, pointless, hateful, and hurtful his actions were. Maybe in his 30s, when this incident is out of the immediacy of tomorrow, he can apply for a job at a McDonald's, get it, and be thankful that the thoughtlessness of his youth has ceased to haunt him for a while.
I'd also like for it to serve as a lesson for any other youths (or anyone, really) sitting on a stupidly nonsensical plan to affect society, that it's not tolerated. When you ruin us, we will ruin you. Repercussions. Consequences. If it's a fine, ok, but make it financially crippling. Put his ass deep in debt before he's old enough to have credit score. Personally, I'd like to see some prison time. Nothing too severe, maybe 6 months, just enough for him to miss homecooked meals and spend his every waking hour with REAL criminals to appreciate that whatever statement he was making chopping that tree down pales in comparison to the REAL evil shit people are capable of. Spend a couple of months being forced to poop in the opposite direction, and watch how quick he joins Greenpeace when he gets out. (Okay, that last part is a bit harsh.)