The first tree in the game, the one you face initially, acts as a mere starting point. After turning your head, you see more trees, kind of a light forest. These trees have no function besides setting the mood. The tree inside is kind of a methaphoical connection to the outside world, but has no function gameplaywise. But in the same room you can find a rather important item. After that, i can assure you, there will be no more confusing trees ;)
