The Influence of the Foodscape on Quaking Aspen stand Condition and use by Ungulates

In order to study the effects of herbivory on plant communities, we determined whether the types and concentrations of chemicals present in different aspen (Populus tremuloides Michx.) stands and understories, i.e., the foodscape, are associated with aspen use by elk (Cervus elaphus L.) and with aspen regeneration and recruitment. Transects were established in aspen stands with high, medium, and low regeneration levels (N=5 locations/regeneration level; ranging from 2,331 m to 2,724 m in elevation) in Wolf Creek Ranch in northern Utah. Using non-metric multidimensional scaling (NMDS) ordination and regression analyses, we examined the relationships between aspen regeneration, recruitment, elk presence, browsing, and other landscape elements with the foodscape (e.g., biomass and chemical composition of the understory and chemical defenses of juvenile aspen trees). The foodscape was affected by elevation and canopy height but it did not explain aspen use or indicators of aspen resilience. Our findings suggest that foodscapes of lower nutrient content–occurring at lower elevations under drier climatic conditions–are more likely to foster aspen stands with less forb and grass understory, and thus lower nutritional biomass. Nevertheless, the extent of the decline in the availability of nutrients in the understory did not appear to influence aspen browsing or indicators of aspen resilience. Future research should focus on exploring the influence of additional–and more contrasting–gradients of chemical availability in the landscape on aspen use by herbivores