VERTEBRATE HERBIVORY IN ARID SYSTEM RESTORATION SUCCESS: AN EXPLORATORY CASE STUDY AND SYSTEMATIC REVIEW

Success of ecological restoration relies on the sourcing of native plants that can successfully be grown commercially and establish at restoration sites. Plants used in the context of restoration face a variety of biotic and abiotic pressures, including herbivory. Vertebrate herbivores have the potential to significantly impact plant establishment and growth, but few studies have investigated how vertebrate herbivory affects plants deployed in restoration efforts. This paper examines the interplay of restoration materials and vertebrate herbivory in two ways. First, we report the results of an exploratory systematic review of papers examining the effects of vertebrate herbivory on restoration materials in the southwestern United States. Impacts on plant fitness varied by herbivore and plant functional group; however, more reported herbivory outcomes were negative than positive or neutral, suggesting that mechanisms to decrease herbivory may be important in restoration. Second, we share the results of a small case study on the effects of vertebrate herbivory on three species of native forbs grown in a common garden setting. We report the effects of vertebrate exclosure caging on plant biomass, height, reproductive output, and survival from two different populations of each species; we also report data from wildlife cameras, rodent track pads, and seed predation trials to establish a better understanding of the community of vertebrates present in the garden. In the case study, we did not find a significant effect of the vertebrate exclosures for either population of any species, despite known herbivore presence. Overall, the results of both the systematic review and case study suggest that although herbivory can have detrimental effects on restoration materials, these effects are highly context dependent. Restoration practitioners may find that plant material selection, vertebrate protection measures such as fencing, and planting timing can be selected to minimize risks from herbivory and maximize restoration effort success.