Short question: If someone hit a cedar tree about a foot wide with enough force to knock down the tree, would that also kill them? Assume that the things which got them up to speed didn't kill them first.
Yes. You are seriously underestimating the strength of trees if you think it's even close, especially a hard wood like cedar. This is the amount of damage a car hitting a tree causes. That tree is about a foot wide, could you imagine how much harder you'd have to hit it to knock it over? Hitting a tree skiing might kill you, and it doesn't even bruise the tree.
That'd probably be best, you couldn't even make the tree smaller, even a small tree will kill you if you hit it hard enough to knock it over. Think about it this way, a baseball bat is the thickness of a very young tree, would the bat kill you before you broke it? (Bats are more breakable than living wood too.)
