Evaluation of nine distance-based measures of functional diversity applied to forest communities

Several methods for the estimation of functional diversity are employed in plant communities. However, it is hard to select the most suitable measures in practice. This work presents comparisons of nine distance-based measures applied to functional diversity analysis in forest communities (36 plots) along an elevational gradient in the Pangquangou Reserve, China. The employed indices and methods were: functional attribute diversity (FAD), Rao’s functional diversity (Rao’s index), single linkage (SL), complete linkage (CL), Unweighted Pair Group Method with Arithmetic Mean (UPGMA), Unweighted Pair-Group Method using Centroids (UPGMC), Median linkage (Median), fuzzy equivalence diversity (Fuzzy index) and minimum spanning tree index (MST). The results showed that all the nine measures successfully quantified the functional diversity in plant communities and described the changes along environmental gradient. It was concluded that all the employed indices and methods were equally effective and significantly correlated. Comparatively, fuzzy index, MST, UPGMC, UPGMA and Median were more suitable and should have priority over the other four measures in functional diversity analysis. A combination of a few measures of functional diversity within the same study was recommended. Functional diversity indices were significantly decreasing with elevation and correlated with species richness in the studied forest communities.