[Stitch moves surprisingly quietly when he wants too, particularly when there's nothing for his claws to clack against. He can smell the man and stealthily makes his way over there. Instinct tells him to pull the tree up, but that might hurt him, so he quells that thought.
Instead he stays hidden under the snow and places all four hands on the tree trunk when he finds it, and gives it an almighty push. The tree practically groans in protest, and only the fact Stitch isn't using his full strength keeps it upright. But it certainly causes the top of it to shake]