I suppose if someone wanted to rob, kill, or rape someone in a forest, declaring it a gun free area would deter them. I mean, they're going to abide by the law in their criminal act, right?
Think of it another way. Just look to our friends to the north, Washington D.C. and Maryland. Strict gun control has worked very well there.
To those that don't understand, this entire post is completely sarcastic. I carry my gun to protect myself from those that'd do me harm.
If they're intent on robbing or killing me, then I don't think they're worried about a weapons violation charge.