A history of botanical field activity in the Cheboygan County region has been prepared by Voss (1956), who reviewed the lumbering activities which date from 1844, although a peak in cutting of timber was not achieved until very late in the century. A number of major fires followed lumbering. Vast areas altered by cutting and burning were pioneered by aspens. Several workers, some dating back to 1909, have investigated stands of aspen in the environs of the University of Michigan Biological Station; their publications are listed by Benninghoff and Cramer (1963). This report is intended to characterize in detail for the year 1976 the arboreal composition of a mature large-toothed aspen (Populus grandidentata) forest in Cheboygan county, in the upper part of Michigan’s lower peninsula, and to establish base-line information for future measurements showing the rate of change as this forest plot is succeeded by a climax forest type. Since the study area is located within the boundaries of the University of Michigan Biological Station at Douglas Lake, its security is enhanced for future long-term comparisons. The widely recognized label for climax forest type in this region is northern hardwoods with hemlock and white pine (Braun, 1950).