Epiphyte species richness increases with tree species richness in boreal forest

Background/Question/Methods

Multi-scale mechanisms control epiphyte diversity; however, the relative importance of the potential drivers at any given scale has rarely been quantified. Explaining epiphyte diversity patterns therefore requires an understanding of the relative roles of the different factors that operate at a given scale. We sampled a chronosequence of stands of varying age and composition in the boreal mixedwood forests of central Canada to determine the relative roles of factors that change with stand development and secondary succession such as stand age, stand type, and basal area, tree species richness, evenness, and tree size and its variation in explaining epiphyte diversity patterns. We quantified the relative importance of these factors on epiphyte species richness using model selection and multi-model inference.

Results/Conclusions

We show that epiphyte species richness is driven by multiple factors. However, among all the factors tree species richness was the single most important driver of epiphyte species richness. Epiphyte species richness increased with tree species richness whereas all the other factors had no detectable effects on species richness. Our results highlight the importance local host diversity as a determinant of epiphyte diversity. Maintaining a multi-tree species community is therefore crucial for the conservation of epiphyte diversity.