Appropriate use levels have not been established for wildlife browsing of true mountain mahogany (Cercocarpus montanus) and this study used exclosures to determine how natural levels of ungulate herbivory affected the growth and reproduction of these shrubs in Utah. Browsing increased annual twig growth, however, twig length of browsed shrubs was lower than unbrowsed shrubs due to length reductions caused by browsing. Flower and seed production were much lower on browsed branches than on unbrowsed branches in all years of the study, indicating that grazing can reduce the reproductive potential of these shrubs. During this three year study, utilization of 29% to 306% of the annual growth of true mountain mahogany maintained shrub size but decreased shrub reproductive potential, and based on these results the authors recommend that the use of these shrubs should not exceed 100% of annual growth.
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