- Woody vegetation including shrubs and scrub trees of non-commercial height and form, often seen in the initial stages of succession following a disturbance. Brush often grows in very dense thickets that are impenetrable to wild animals and serve to suppress the growth of more desirable crop trees. However, brush can also serve an important function as desirable habitat for a range or bird, animal, and invertebrate species, and often provides a good source of browse and cover for larger wildlife. It adds structural diversity within the forest and is important in riparian zones. It is also termed scrub.