From the Dust Bowl to the Green Glacier: Human Activity and Environmental Change in Great Plains Grasslands

Abstract

Before European settlement, the land between the Rocky Mountains and the Mississippi River of North America formed immense unbroken grasslands devoid of trees except those few forming gallery forests along lower river channels and those located in disjunct topoedaphic sites protected from fire. The Great Plains grasslands are now extensively fragmented by cropland agriculture, human occupation, and woody plant encroachment and altered directly and indirectly by livestock grazing and other anthropogenic disturbances. As a consequence of these processes, today’s grasslands bear little resemblance to those of pre-European settlement and are now recognized as one of the most endangered ecosystems in North America (Sampson and Knopf 1994). Awareness of the unique biodiversity of the Great Plains and its importance to our natural heritage has highlighted the need for a regional approach to conservation of remnant grasslands (Joern and Keeler 1995; Mitchell et al. 1999). In part, this need is urgent because many of the species endemic to the region are declining rapidly.