Escaping herbivory: refuge effects on the morphology and shoot demography of the clonal forest herb Maianthemum canadense

High levels of herbivory can reduce plant growth, reproduction, and ultimately, abundance. I compared the morphology and shoot demography of Maianthemum canadense on large boulder tops, which were inaccessible to white-tailed deer, and on small boulder tops, which are browsed. Vegetative shoots tended to be larger on boulder tops, but there were no differences between large and small boulder tops in internodal rhizome lengths or branching frequencies. Shoot densities, frequency of occurrence of flowering shoots, and frequency of flowering shoots within quadrats were higher on large boulder tops than small boulder tops. Such differences were not observed in Oxalis acetosella, a species which is not browsed. Similar patterns have been reported for other forest herbs throughout the eastern United States from locations where browsing pressure is great. Refugia may allow browse-sensitive plants to persist, albeit at lower densities, in overbrowsed habitats.