The thing about trees is that they know what to do. When a leaf loses its colour, it's not because its time is up and it's dying, it's because the tree is taking back into itself the nutrients the leaf's been holding in reserve for it, out there on the twig, and why leaves change colour in autumn is because the tree is preparing for winter, it's filling itself with its own stored health so it can withstand the season. Then, clever tree, it literally pushes the used leaf off with the growth that's coming behind it. But because that growth has to protect itself through winter too, the tree fills the little wound in its branch or twig where the leaf was with a protective corky stuff which seals it against cold and bacteria.
Otherwise every leaf lost would be an open wound on a tree and a single tree would be covered in thousands of little wounds.
Clever trees.
