Here's my take, having just read it for the first time (thanks for the link, benbradley):
There's no allegory. It's a tree. It didn't actually say any of those things, because trees and humans can't communicate with each other.
So.
Stop raping the planet in your lame, ineffectual attempts to be "happy," you stupid, selfish humans! At the very least, don't justify your pillaging with claims the trees are all fine and dandy with you cutting them all down!
I'm mostly kidding. But I was raised in a conservative Christian home where it was taught the earth was made "for us" and we were given "dominion" over all the other creatures, so that's were my (admittedly literal) mind went. Frame of reference can be fun.