Ten study plots on the Fitch Natural History Reservation were checked for invading arborescent vegetation in 1999 after 50 years of protection as a natural area. These plots were treeless or nearly so in 1948. Plots were one hectare (8), 0.52 hectare (1), and 1.30 hectare (1). All trees of 6 cm or more in diameter breast high were counted, and totaled 6,530 of 25 species with American elm, Osage orange, white ash, black walnut, common hackberry, honey locust, red cedar, Plains cottonwood, black oak, black cherry, redbud, and red mulberry as the most important species, and with 13 other species each less than one percent. The climax oaks and hickory constituted 3.5% of the total. Trees reached maximum abundance on two bottomland plots that earlier had been cultivated. Upland areas, including prairie, old-fields and former pasture were somewhat less productive in terms of tree numbers, but some were more diverse or were characterized by a larger average basal area per tree than the old-field bottomlands.