I can explain why dragons can't be arboreal, first of all, the term arboreal refers to animals that live in trees, like momongas, monkeys, tree snakes ...etc, so to have an arboral dragon, the dragon must live in a tree, so, unless the dragon is as big as a lizard, he will be breaking lots of branches and usually fall down, second, dragons are (usually) aggressive and territorial, traits that are usually not found among arboreal creatures, and third, dragons shoot fire, which is why dragon's nests doesn't have much flora arround it. and, dragins have wings, and fying is hard in the woods, and since wings must be bigger than the size of the body, they won't be able to fly.
so, unless a dragon doesn't have wings, can't spit fire, and is tiny. he can't be arboreal, and any dragon like that is actually a "Lizard" and not a dragon. so, petaldramon should have his name changed