COVER COMPONENTS ON LONG-TERM SEASONAL SHEEP GRAZING TREATMENTS IN 3-TIP SAGEBRUSH STEPPE

The effects of fall and spring sheep use on cover components and recov ery following a change in seasonality of grazing practices, were studi ed within long-term grazing treatments of three-tip sagebrush (Artemis ia tripartita Rydb.) steppe on the U.S. Sheep Experiment Station near Dubois, Ida. Few significant differences existed among treatments with in the litter, moss, lichen, and soil components, but several differen ces in vegetational cover categories occurred. More live shrub and ann ual grass cover were observed in the long-term (since 1924) and new sp ring (since 1950) treatments than in the long-term fall (since 1924), new fall (since 1950), old exclosure (since 1940), and new exclosure ( since 1950) (P < 0.01). More perennial grass and forb cover, and less dead shrub cover existed in fall-grazed treatments (P < 0.01). The new fall-grazed treatment previously grazed in the spring failed to reach a more uniform mixture of perennial growth forms after 46 years such as was evident in the long-term fall, which suggests low resilience fo llowing spring grazing. The exclosure which was heavily spring and fal l-grazed prior to 1950 had even less perennial forb cover than the new fall treatment, indicating that the cessation of sheep grazing did no t promote herb recovery any better than continued fall use. The direct impact of sheep herbivory and its indirect effects on the competitive relationships among major plants appear to have affected the cover of sagebrush steppe components at this study site.