Th e national FIA plot design (Fig. 1) consists of four 24-ft-radius subplots confi gured as a central subplot and three peripheral subplots. Centers of the peripheral subplots are located at distances of 120 ft and at azimuths of 0, 120, and 240 from the center of the central subplot. Each tree with diameter at breast height (d.b.h.) 5 inches or greater is measured on these subplots. Each subplot contains a 6.8-ft-radius microplot with center located 12 ft east of the subplot center on which each tree with d.b.h. between 1 and 5 inches is measured. Factors that diff erentiate forest conditions include forest type, stand-size class, stand origin, land use, ownership, and density. Forest conditions that occur on any of the four subplots are identifi ed and recorded; if the area of the condition is 1 acre or greater, the condition is mapped on the subplot.