MIGRATIONS OF GRASSLAND COMMUNITIES AND GRAZING PHILOSOPHIES IN THE GREAT PLAINS: A REVIEW AND IMPLICATIONS FOR MANAGEMENT

ABSTRACT-Ecologists commonly separate Great Plains grasslands communities into types based on grass height: shortgrass prairie, mixed-grass prairie, and tallgrass prairie. Grass height correlates directly with precipitation and thus lessens with distance westward and with drought. Grass height correlates inversely with grazing intensity and thus short-grasses expand eastward when grazing pressures are great and shrink westward when grazing pressures relax. Evidence about past distribu-tions of shortgrasses, coupled with the prehistoric and historic abun-dances of large grazers and the black-tailed prairie dog (a shortgrass indicator), suggest a far-eastward occurrence of shortgrass prairie in the late Pleistocene (despite a relatively wet climate), a shrinkage westward by late prehistoric and early historic times, and a farther shift westward in response to the bison's demise in the 19th century. After cattle arrived in the late 1800s, shortgrass prairie expanded and contracted dependin