Grassland

Grassland
The North American prairie biome is one of the most extensive grasslands in the world, extending from the Rocky Mountain edge on the west to the eastern deciduous forest on the east, and from northern Mexico in the south to the Canadian provinces of Alberta, Saskatchewan, and Manitoba in the north. The original grassland associations of plants and animals have been almost completely destroyed by humans. The prairies today have been transformed into the most productive agricultural region in the world, dominated by monocultures of cereal grains. In grazing lands virtually all the major native grasses have been replaced by alien species. Vast areas of Arizona and New Mexico have been converted from lush grasslands to parched desert by more than a century of livestock overgrazing. Of the once dominant herbivore, bison (Figure 39-9), very few survive, but jackrabbits, prairie dogs, ground squirrels, and antelope remain. Mammalian predators include coyotes, ferrets, and badgers, although, of these, only coyotes are common. Rainfall on the North American prairie ranges from about 80 cm (31 inches) in the east to 40 cm (16 inches) in the west. Average annual temperatures range between 10° and 20° C (50° to 68° F).