Succession-nothing in plant, community, or ecosystem ecology has been so elaborated by terminology, so much reviewed, and yet so much the center of controversy. In a general sense, every ecologist uses the concept in teaching and research, but no two ecologists seem to have a unified concept of the details of succession. The word was used by Thoreau to describe, from a naturalist's point of view, the general changes observed during the transition of an old field to a forest. As data accumulated, a lengthy taxonomy of succession developed around early twentieth century ecologists such as...