The tallgrass prairie, though at first appearing to be a monotonous sea of grass dominated by a handful of tall perennial grasses such as big bluestem, little bluestem, Indian grass, and switchgrass, contains great biological diversity. The grassland, woodland, and stream habitats of Konza contain over 600 species of plants, approximately 300 species of vertebrates, and several hundred species of insects, small soil organisms, and aquatic organisms. This diversity is maintained by complex interactions of grazers, fire, topography, soils, and a variable mid-continental climate. The tallgrass prairie once stretched over most of what is now Iowa, Illinois, southern Minnesota, northern Missouri, and the eastern portions of the Dakotas, Nebraska, Kansas, and Oklahoma, but most of this region was converted to farmland during the westward expansion in the 1800's, leaving only a small fraction of the original prairie. In the Kansas Flint Hills, however, steep slopes and rocky soils defied the plow, and about 5 million acres remain as the largest contiguous area of tall grass prairie in North America, where periodic fire and grazing remain important management practices.