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The effects of 59 years of winter and spring grazing on a Great Basin salt-desert shrubland were analyzed using frequency and cover data. Spring grazing altered species composition more than winter grazing when compared to the nongrazed exclosures. Grazing in both seasons resulted in significant decreases in shrub importance. Introduced annuals increased in importance with spring grazing. Spring-grazed pastures show patterns of destabilization that are missing from winter-grazed pastures and nongrazed exclosures.