Measuring species diversity in a subtropical forest across a tree size gradient: A comparison of diversity indices

Shannon-wiener index and simpson′s diversity index together with other metrics,e.g.,richness,number of stems per species or species-specific density (n: s ratio),and kurtosis,were applied to characterize the woody plant diversity patterns of a subtropical broadleaved forest in south china. the aims of our study were to compare the efficacy and sensitivity to community diversity measures between shannon-wiener index and simpson′s diversity index. tree census data from a 5-ha sample plot was partitioned into 3 datasets by diameter class to represent 3 distinct woody plant communities for the characterization of diversity across communities. the 5-ha sample plot of the forest had a total abundance of 23,301 tree stems ≥ 1 cm dbh and a richness of 139 species. the majority of tree stems were seedlings (41.1%) and saplings (38.8%),whereas canopy trees only accounted for 20.1% of the total tree stems. both shannon-wiener index and simpson′s diversity index decreased significantly in response to a decrease in the n: s ratio across the datasets,but shannon-wiener index was more sensitive to plot-based richness changes and had a higher efficacy in predicting changes in species richness. our findings are contrary to the general belief that shannon-wiener index is an insensitive measure of the character of the n: s relationship and have demonstrated that it remains a good measure for species diversity in plant community studies for its sensitivity and efficacy. we also suggest that the kurtosis statistic can be used as a new diversity measure due to its sensitivity to diversity change. © 2017,pakistan botanical society. all rights reserved.