Changes in White-Tailed Deer Browsing Selection of Hardwood Tree Species with Increasing Stem Height

Abstract

To forage optimally, deer select individual plants highest in limiting nutrients, while avoiding individuals that are high in anti-herbivore defenses. For some woody species, deer may selectively browse on larger stems, which can provide a larger amount of younger, more nutritious tissue per individual. However, in some species, larger stems may possess increased levels of anti-herbivore defenses, ultimately discouraging deer from browsing on these larger individuals. We examined differences in the proportion of twigs and stems (individual seedlings/saplings/trees) browsed across three height classes for four species: blue ash (Fraxinus quadrangulata Michx,), white ash (F. americana L.), sassafras (Sassafras albidium Nutt.), and sugar maple (Acer saccharum L.), across multiple sites in central Indiana. Overall, we found that taller stems had a higher likelihood of being browsed, but smaller stems were browsed more heavily. We also found that sugar maple twigs and stems were most likely to be browsed, while sassafras twigs and white ash twigs and stems were least likely to be browsed. Our results indicate that under intense browsing pressure, preference should be given to smaller stems for protection, and that stands with greater vertical stratification of palatable species are more resilient to the effects of deer browsing.