Oklahoma is a state in the South Central region of the United States, bordered by Texas on the south and west, Kansas on the north, Missouri on the northeast, Arkansas on the east, New Mexico on the west, and Colorado on the northwest.
Due to Oklahoma's location at the confluence of many geographic regions, the state's climatic regions have a high rate of biodiversity. Forests cover 24 percent of Oklahoma and prairie grasslands composed of shortgrass, mixed-grass, and tallgrass prairie, harbor expansive ecosystems in the state's central and western portions, although cropland has largely replaced native grasses. Where rainfall is sparse in the state's western regions, shortgrass prairie and shrublands are the most prominent ecosystems, though pinyon pines, red cedar, and ponderosa pines grow near rivers and creek beds in the panhandle's far western reaches. Southwestern Oklahoma contains many rare, disjunct species including sugar maple, bigtooth maple, nolina and Texas live oak.
Marshlands, cypress forests and mixtures of shortleaf pine, loblolly pine, blue palmetto, and deciduous forests dominate the state's southeastern quarter, while mixtures of largely post oak, elm, red cedar and pine forests cover northeastern Oklahoma.
The state holds populations of white-tailed deer, mule deer, antelope, coyotes, mountain lions, bobcats, elk, and birds such as quail, doves, cardinals, bald eagles, red-tailed hawks, and pheasants. In prairie ecosystems, American bison, greater prairie chickens, badgers, and armadillo are common, and some of the nation's largest prairie dog towns inhabit shortgrass prairie in the state's panhandle. The Cross Timbers, a region transitioning from prairie to woodlands in Central Oklahoma, harbors 351 vertebrate species. The Ouachita Mountains are home to black bear, red fox, gray fox, and river otter populations, which coexist with 328 vertebrate species in southeastern Oklahoma. Also, in southeastern Oklahoma lives the American alligator.