In this review article, Ripple and Beschta examine the decline of deciduous woody species, found along riparian systems in the western U.S., and the need for restoration of those species at landscape scales. Such restorations would be facilitated if reference sites existed that were relatively unimpacted by ungulate herbivory (refugia), since they can provide an understanding of vegetation dynamics without the effects of herbivory. These areas can also help define the degree and extent of degradation in woody plant communities for other portions of the landscape, and possibly assist in setting restoration priorities by providing important targets for restoration programs. This article proposes three situations where refugia for deciduous woody browse species are likely to persist: (1) Where the browsing is predominantly from domestic ungulates, physical barriers to site access will control the occurrence of refugia, (2) Where wild ungulates are present but natural predators are not, both physical barriers and predation risk associated with human hunting will tend to control the occurrence of refugia, and (3) Where natural predators have a significant presence, physical barriers and terrain features that affect the perceived predation risk of prey animals at varying spatial scales will influence the number, size, and spatial distribution of refugia. It is suggested that identification of refugia across watersheds and other landscapes is needed to better understand reference conditions for woody browse species that may have existed prior to the influences of domestic livestock and the effects of native ungulates where major predators have been extirpated.
Citations and enhanced abstracts for journals articles and documents focused on rangeland ecology and management. RSIS is a collaboration between Montana State University, University of Idaho, and University of Wyoming.