Impacts of livestock grazing in sagebrush ecosystems.
Havstad, Kris *,1, Vavra, Marty 2, 1 USDA, ARS, Las Cruces, NM2 Starkey Experimental Forest, La Grande, OR
ABSTRACT- Differential impacts of grazing by domestic livestock as a function of stocking rates (land area/animal numbers/time) on western rangelands have been recognized for decades. In the sagebrush steppe the general impacts of chronically excessive stocking rates are typically negative, long-lasting, and usually complicated by concurrent episodic disturbances (such as drought, fire, and species introductions). There are numerous general theories on the role of large ungulates in shaping rangeland systems, and though domestication has altered some behaviors of their historic predecessors, inherent foraging behaviors of livestock are similar to other wild ungulates. Today the issues surrounding grazing impacts by livestock revolve less around excessive uses and more about chronic direct and indirect impacts of preference, presence, and pattern of use. This review will acknowledge the well-recognized impacts of excessive use, describe associated impacts (such as landscape fragmentation, predator control, and encroaching or invasive species), and characterize the more pervasive direct and indirect impacts of managed grazing on sagebrush steppe rangelands.
Key words: management, sheep, rangeland, cattle
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