It's not the most scientific explanation I've ever heard but it made me laugh, as I thought of some teenage rooms I have known. So I took a photo of this teenage forest, of the downed trees, crowded saplings and logs like random tennis shoes.
But the forest grows up too. The mature growth crowds the patchy sunlight that allows young trees to grow. The old growth forest is placid and lofty and purposeful.
Not nearly as much fun, though.