Tallgrass prairie is capable of supporting significant biodiversity. Parts of the ecoregion are among the "top ten ecoregions for reptiles, birds, butterflies, and tree species. Tallgrass species are found in the understory layer." Oak (blackjack oak (Quercus marilandica) and post oak (Q. stellata) ) and hickory tree species occur in some areas, but generally in moderate densities. Bison (Bison bison) were a dominant species.
