A bison herd located in Iowa has calved the first bison calf, on the prairie, in 150 years. This herd was established specifically for conservation purposes. It is one of two “pure” bison herds, meaning that they have no cattle genes in their gene pool. Twenty-eight “pure” bison were introduced to the Broken Kettle Grasslands, in Iowa. Conservationist at Broken Kettle Grasslands believe that if this herd continues to grow they can help with prairie conservations efforts in Iowa.
According to American Prairie Foundation, at one point 20 to 60 million bison roamed the Great Plains there are only 500,000 bison in North America today and of these less than four percent (about 19,000 bison) live in conservation herds. Researchers are beginning to understand how fewer bison affect the prairies.
In Paulette Noser’s paper, Fire and Bison Grazing, Historic Strategies Used to Restore Custer State Park’s Mixed Grass Prairie, she explains how bison grazing leads to the restoration of the prairie, because they restore the native mixed grasses to the prairie and prevent pine and woody plants from growing in the prairie.
“Bison impact prairie species diversity in their selection of forage. The selectivity of bison grazing can be used as a technique to reduce the abundance of some species and thereby increase species diversity by allowing others to compete (Paulsen 1975). The mosaic habitat patches generated by bison grazing and non-grazing habits likely increased species diversity that would otherwise be excluded from the community by competition from the matrix grasses (Hartnet et al. 1996).” And increased biodiversity translates to a healthier ecosystem. Overgrazing, especially by elk and buffalo lead to prairie degradation. Conservationists are carefully managing the bison herds to ensure they continue to aid in the restoration of the prairies and not further the breakdown of the ecosystem. One way this is done is by measuring the rainfall. The rainfall signals to researchers the amount of grasses that will grow that year and therefore translates into the number of bison the prairie can maintain. The excess bison are sold in the fall to prevent overgrazing.
The second way bison help maintain the prairie is by preventing pine and woody plant encroachment. The bison graze, browse and trample the these plants, which prevents them from growing and taking over the prairie.
Because of these benefits conservationists are hoping to eventually have 200 bison living in Broken Kettle Grasslands. More bison will be introduced to the area, but there is a hope that the bison population will continue to grow and reproduce without human intervention. The birth of a calf indicates that the population is genetically diverse and stable enough to support a calf. It also indicates that the prairie is healthy enough to support additional individuals.