Park vegetation features mostly second growth forests of various vintages, and small areas of old growth. Approximately 45% of park land was fields and pastures prior to park establishment. These old fields are largely dominated by eastern red cedar and Virginia pine mixed with deciduous trees along the outer margins. More mature upland sites are generally oak hickory forest, and in moist hollows, beech-maple-tulip poplar forest dominates. Along the Green and Nolin Rivers, sycamore, silver poplar, river birch, box elder and American elm are found. Special communities of limited distribution include upland swamps with pin oak, red sweetgum, and red maple; deep sandstone hollows with hemlock and umbrella magnolia; dry limestone cedar oak glades; and cliff margin stands of Virginia pine on sandstone cliff margins. Patches of prairie, locally called barrens due to the lack of trees, were originally maintained by Native Americans through burning, and now exist in remnant patches in the park. Efforts at native prairie restoration are now underway.