Great bison belt

The great bison belt is a tract of rich grassland that ran from Alaska to the Gulf of Mexico around 9000 BC. The great bison belt was supported by spring and early summer rainfall that allowed short grasses to grow. These grasses retain their moisture at the roots which allowed for grazing ungulates such as bison to find high-quality nutritious food in autumn.

These grasses are what allowed the bison population to thrive, as they were able to receive all of their nutrients from the short grasses, unlike other Ice Age animals which expanded in the postglacial period. This area was important to the Plains Paleo-Indians, who around 8500 BC turned to bison hunting instead of hunting a broader range of food.

About 50-75 million years ago, surging molten rock formed the mountain ranges of the west, including the Black Hills. About 10 million years ago, geological forces shaped the rest of the Great Bison Belt, the largest terrestrial biome in North America. When the Pleistocene epoch ended about 10,000 years ago, warmer and drier weather came to dominate the region, making the biome ideal for grasslands and vegetation. Before human intervention, the Great Bison Belt included most of the present-day United States as well as parts of Canada and Mexico. It stretched from Southern Mexico to Northern Canada, and from California to Virginia.

The environment of the Great Bison Belt has been defined by low rainfall, typically less than 24 inches per year. In drier areas, annual rainfall was less than 16 inches. The area has also been unstable and unpredictable. Periods of drought could quickly be replaced by excessive rainfall. There have been important regional differences to the environment. The southern plains, including the Texas panhandle, often received greater winds and less precipitation than regions to the north, such as North and South Dakota. As a result, droughts have been more prevalent in the southern regions of the Great Bison Belt. The droughts could be so severe that early explorers called it the Great American Desert. The Canadian prairies are similar to the grasslands of the American plains, although farmers deforested much of the region and converted grassland to farmland. The area from Northern Alberta to Alaska is mostly woodlands, and supported smaller groups of non-migratory wood bison.

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Wikipedia