That's an interesting scenario... tree is a permanent fixture as others have pointed out; however I wonder if there are times when you can't easily tell if the ball actually brushed a leaf, or passed through cleanly? Also, what if you lose sight of the ball as it's going through the tree; even if it does not end up hitting any leaves, is the fact that your vision is obstructed grounds for anything?
Funny and true story: I once hit a bird in flight! Big pelican or whatever, flying maybe 30 ft over the court as I hit a lob; ball hit the bird and fell into the court. We had no idea what the correct call was at the time, so we just played a let (after we recovered from laughing)