Relationship between species richness and functional diversity of leaf traits in two evergreen species assemblages in a temperate rainforest

Abstract

The temperate rainforest (southern Chile) consists of several forest types that differ in composition and species dominance. These differences should determine changes in biodiversity components that are correlated among them. This study determined whether there is a link between woody species richness (S) and functional diversity of leaf traits, in two forest assemblages that differ in floristic composition: Valdivian and Coihue forest types. It was tested: i) whether there is an overall positive relationship between functional diversity and S; and ii) given that both assemblages differ in woody species composition, whether the magnitude of the relationship between functional diversity and S differ among the two forest types. The indexes community-weighted-mean (CWM) and functional divergence (FDvg) of the leaf traits leaf mass area (LMA) and relative chlorophyll content (Chlr), were used to describe the functional diversity. These leaf traits and species abundances were measured in all woody species occurring in both forest types (10 plots 225 m2 per forest type). There was an overall positive relationship only between FDvg-LMA and S. The same pattern emerged when this relationship was evaluated within each forest type, independent of the fact that these communities have different dominant species, and also differ in average FDvg-LMA. However, when comparing the magnitude of this relationship between the two forest assemblages no significant differences were found. Woody species richness can be a good surrogate of functional diversity in forest communities in the temperate rainforest, depending on the functional trait selected to infer this diversity component. Hence, it is possible to infer that the greater woody species richness in these forest communities, the greater is the likelihood to find species that differ in functional leaf traits as LMA.