Some mosses will happily grow over almost any surface, while many mosses are are more particular of their growing substrate. As a general rule, if the moss does not appear to have ‘roots’ (moss does not have true roots), the moss will happily grow on almost anything, such ascork or wood. If the moss appears to have ‘roots’, and grows in a mat-like fashion, such as mood moss, it generally prefers a soil-like substrate, such as ABG mix or sphagnum. Once again, if you’re not sure what your moss likes, split it up and spread it around.
Some mosses are perfectly fine growing directly on wood, and do not require special substrates.