Submitted to: Society for Ecological Restoration Symposium
Publication Type: Abstract Only
Publication Acceptance Date: April 6, 2003
Publication Date: November 19, 2003
Citation: Young, J.A., Clements, D.D. 2003. History of the great basin, cumulative impacts, livestock and weeds [abstract]. Society for Ecological Restoration Symposium. p. 63. Technical Abstract: The Great Basin is a vast area reaching from the Sierra-Cascade Mountains to the Rocky Mountains. During the Pleistocene, lakes formed in the hydrological basins with the Great Basin. Lake Bonneville and Lake Lahontan are well known pluvial lakes from this glacial epoch. The desiccation of these lakes during the Holocene left the lake plains with soils highly influenced by soluable salts. Wind erosion of lake plains and glacial river deltas subsequent to desiccation has greatly influenced the development of soils in the Great Basin. Periodically, during the Holocene, large herbivore populations expanded and contracted across the Great Basin. At the time of European contact, the American bison (Bison bison) was found only in far northeastern portion of the Great Basin. The Holocene vegetation evolved from the wreckage of vegetation that existed a much more and abundant biologically effective period of glacial epochs. The overstory was dominated by woody species of sagebrush (Artemisia sp.) with understories dominated by perennial grasses. Cattle and horses were introduced quite suddenly in the 1870s and 1880s. The concentration of excessive numbers of livestock during the late winter, early spring, summer, and fall seasons year after year resulted in the weakening and eventual killing of native perennial grasses. This allowed a biological significant increase in long-lived native shrubs. The void of native herbaceous species in the understory of shrub communities was eventually filled by exotic, self invasive annual species which formed a seral continuum, ultimately resulting in cheatgrass (Bromus tectorum) dominance. Cheatgrass increased the chance of ignition, rate of spread, and extended the season of wildfires. This greatly reduced the interval between wildfires and most importantly, in terms of restoration, resulted in biologically significant changes in site potential.