Species-Specific Responses Drive Browsing Impacts on Physiological and Functional Traits in Coast Live Oak (Quercus agrifolia) and Bay Laurel (Umbellularia californica)

Abstract

Herbivory is a fundamental ecological force in the evolution of plant physiological, morphological, and chemical attributes. In this study, we explored how browsing pressure by local deer populations affected leaf form and function in two California native tree species, coast live oak (Quercus agrifolia) and bay laurel (Umbellularia californica). Specifically, we investigated how leaf and stem vascular attributes shifted between browsed and non-browsed zones of each species and tested for differences in trait coordination as well as stem-leaf function. Browsing significantly altered traits such as leaf to phloem ratios and leaf area, but we observed few meaningful differences in leaf and stem anatomy between browsed and non-browsed material. We discuss these results in the context of such additional ecological factors and explore future research considerations for investigating leaf and stem vascular trait development with herbivore presence.