Old growth forests can have a variety of different characteristics, but most have significant numbers of trees over 150 years old, large diameter trees, a wide distribution of tree sizes, and a large volume of coarse woody debris (i.e., downed trees). In Maryland, the Department of Natural Resources (DNR) defines old growth areas as areas containing a minimum of five acres with mostly older trees, the oldest of which exceed half the projected maximum attainable age for the species (Jolly, p.7.).