Forage diversity, type and abundance influence winter resource selection by white‐tailed deer

QUESTIONS: The presence of a plant species can influence the selection of another plant species by herbivores. Natural communities encompass several plant species, and in these multi‐species environments, resource selection by herbivores could be partly explained by plant diversity. Our objective was to determine how winter consumption by a large herbivore (white‐tailed deer) varies relative to the diversity and composition of the plant community in a temperate forest. (a) Does browsing increases or decreases with diversity indices; and (b) are specific community compositions linked to high or low browsing by deer? We also aimed to determine whether neighbouring plant diversity and identity could modify browsing on a specific species, Pinus strobus (hereafter pine). LOCATION: Vallee de la Gatineau, Quebec, Canada. METHODS: We sampled 102 plots in the sugar maple (Acer saccharum)–basswood (Tilia americana) subdomain, a deciduous type of forest in the northern temperate zone. Each plot was centred on a pine and browsing by deer, plot diversity and composition were measured. RESULTS: Total browsing and browsing on focal pines decreased with increasing values of diversity indices, but only in plots with high resource abundance. This result is in accordance with optimal foraging principles, as diversified plots have a lower concentration of preferred species. Total consumption did not vary with plot composition, but browsing on the focal pine decreased with increased abundance of Diervilla lonicera and Lonicera canadensis, abundant deciduous shrubs. This associational defence could protect vulnerable pines from deer browsing. CONCLUSION: While our study revealed a relationship between plant community diversity and winter browse use and selection by deer, it also highlighted the importance of resource abundance and community composition – variables influencing the resource selection process. Diversity measures can describe vegetation communities, but probably do not represent the way in which herbivores perceive their environment.