Christ, you guys are really bad a watching movies. Did you not notice that some people lived while others died? It had nothing to cutting down trees. The people that lived where the ones that had an absence of anger / knew love. It was a freak'n love story. Marky Mark's character was great, and I thought it would be clear to everyone.
What's funny, is the one thing I hate about M night is he sometimes clearly spells out things for dumb people; I like it better when there is no "reveal" and you're left wondering what the point of the story was. The ending was perfect because there was no, "looke at me, this is what the movie was about!" moment. I thought for sure when Marky's character left the cabin to spend his dieing moments with the woman he loved only to be spared by the trees would be clear enough for everyone; but it apparently it wasn't. As when I was taking a piss after the movie and heard a couple of guys pondering the ending... I told them the people survived because they "had love in their heart" they just laughed at me and walked away. dumb asses.