Forum: A Change in the Ecological Understanding of Rangelands in the Great Basin and Intermountain West and Implications for Management: Revisiting Mack and Thompson (1982)

Abstract

Reevaluating assumptions about the ecology and management of sagebrush and salt desert shrub systems in the Great Basin and Intermountain West is a proper role for science. These are complex rangeland ecosystems, and our management applications need to account for this complexity. Understanding and reckoning this complexity is vital to the future existence of these rangeland systems and their ability to provide critical goods and ecosystem services to society. The most influential ecological claim of the past 40 yr is based on ideas presented by Mack and Thompson (1982), that Great Basin and Intermountain West plant communities evolved with few or perhaps no large hooved-grazing animals. Our thesis asserts that Mack and Thompson's position is based on 1) an oversimplification of complex, heterogeneous, and diverse ecosystems; 2) a poor understanding of science, both in 1982 and now; and 3) the attribution of all recent ecological changes to a single land use. We review the archaeological and historical record of vegetation and large grazing animals in the region and then revisit Mack and Thompson's (1982) interpretations of the rangeland plants and plant communities, forage quality and nutrition, and soil biotic crusts east and west of the Rocky Mountains, adding the information necessary for a more comprehensive interpretation. We finish by proposing an alternative paradigm to guide management and conservation of sagebrush and salt desert systems of the Great Basin and Intermountain West and beyond.