Where Bison Graze, Grasslands Thrive
The prairies where the bison roam are likely to be more ecologically healthy than other prairies in North America.
Research conducted in northeastern Kansas has revealed that grazing, particularly by bison, increases grassland biodiversity, even under conditions that reduce diversity, such as nitrogen addition and frequent burning.
This grazing effect was noticed in two experiments conducted by NSF ecologist Scott Collins and his colleagues at NSF's Konza Prairie Long-Term Ecological Research (LTER) site. In one experiment, grassland species diversity noticeably declined on burned and fertilized areas, but not in grazing areas. In the other, loss of species diversity caused by frequent burning was reversed by bison grazing.
North America's prairie ecosystem has been disrupted by reduced populations of bison and other grazers, nutrient imbalances in the atmosphere, and inconsistency in the occurrence of fires, according to Collins. Some researchers believe that less than 10 percent of the original prairie in North America still remains, he adds.
Collins points out that burning is not the single most effective way to manage these regions. He recommends grazing as a solution that should be introduced throughout the tallgrass prairies of North America.