Inhabiting or frequenting trees - arboreal, tree-living
Abounding in trees "an arboreous landscape" - arboraceous, woodsy, woody
Resembling a tree in form and branching structure - arboreal, arborescent, arboresque, arboriform, dendriform, dendroid, dendroidal, treelike, tree-shaped
See also: arbor [N. Amer, Austral], branchy, wooded