The post-oak barrens of Buffalo National River represent transitional zones between glades and hardwood forests. Typically, they occur on shallow soils and contain floristic elements of both glades and forests. Prairie forbs are common under the open tree canopy characteristic of barrens (10-50% tree cover). The dominant trees of the barrens, post oak (Quercus stellata) and black-jack oak (Quercus marilandica) are well adapted to shallow soils, drought, and fire that are the natural perturbations of this ecotone. Barrens or savannas often yield the highest diversity of plants and wildlife in the Midwest because they support both prairie and forest species and are uniquely adapted to natural disturbances.