IMPACTS OF MULE DEER AND HORSE GRAZING ON TRANSPLANTED SHRUBS FOR REVEGETATION

Revegetation success on foothill ranges in northern Utah using big sagebrush (Artemisia tridentata Nutt. spp. wyomingensis Beetle and Young) and rubber rabbitbrush (Chrysothamnus nauseosus Britt. spp. albicaulis H. and C.) was determined as influenced by winter mule deer browsing and spring horse grazing. Treatment areas of 0.1 ha with 3 replications included a protected control, use by deer only, use by horses only, use by deer and horses, and use by deer with horse grazing delayed for 3 years after seedling transplant. Results from the first 6 growing seasons following transplanting of seedlings showed grazing by horses only tripled the available, per-plant browse production of big sagebrush compared to protected plots, whereas browsing by deer only resulted in a 40% decrease in browse production. Seedling survival of big sagebrush differed between treatments during the first 3 growing seasons but was not affected by grazing after the third growing season. Rubber rabbitbrush was not affected by treatments.