Eighty-nine upland forest stands were selected to cover the ranges of tree species composition, stand ages, understory composition, and site in the area. The role of each tree species as a pioneer, transient, or self-maintaining component of the forest was determined from the number of stems, their vigor, and distribution in tree, sapling, and seedling strata among all stands and from growth increment cores of trees and saplings in 39 stands. Conclusions are drawn regarding the species likely to dominate different sites following severe fire and the kinds of vegetational change likely to occur on them between disturbances. Changing patterns in the non-arboreal vascular flora, moss, and lichen cover were related to changes in tree species composition with site and time. The forest and its environment are linked in an irregular "pulse" strategy of alternating disturbance and regrowth that repeatedly rejuvenates the growing stock.