Importance of functional diversity, as well as species richness, as a descriptor of community assembly process has been increasingly stressed. However, a relationship between the two aspects of biodiversity is not well-understood yet. Thus, in this study, we analyzed variation of functional diversity along a gradient of species richness of understory plants in a cold-temperate forest.

Species composition and five functional traits of the recorded species were collected for 129 1m² quadrats located across four land-use types, i.e. primary forest, secondary forest, fir plantation and larch plantation. Four indices of functional diversity, i.e. FRic, FEve, FDiv and FDis, were calculated.

Standardized effect size (SES) of FRic was significantly negatively correlated with species richness within primary forest while those of the other three indices were relatively independent of species richness. In the comparison among land-use types, SES of FRic tend to be negative in primary and secondary forests, where species richness was higher than in plantations. SES of FEve were not significantly different from 0 in all land-use types. SES of FDiv tend to be positive in plantations and SES of FDis tend to be negative in non-plantations. Meanings of these results will be discussed in our poster from both basic and applied perspectives.