If it has to do with trees, you can call it arboreal. Monkeys that live in trees are arboreal. The rings of a tree are an indication of arboreal age.
The word arboreal comes from the Latin arboreus, which means "pertaining to trees." It's a word that refers not just to animals that live in trees, but also to anything that resembles the branching form of a tree — like a chandelier or a family geology drawn out. It even can be used to describe, as its Latin root suggests, something pertaining to trees. A Christmas tree shop is an arboreal wonderland. There are trees everywhere!