The calculation of Simpson, Shannon-Weiner, and Pielou
indices
The Simpson and Shannon-Weiner indices are both comprehensive indices of
richness and evenness, but the Simpson index is more sensitive to
species evenness, and the Shannon-Weiner index is more sensitive to
species richness (Xu et al., 2011). These indices are usually used
together to comprehensively evaluate species diversity (Heip et al.,
1998). The Simpson index is calculated as
\(D=1-\sum_{i=1}^{s}{P_{i}}^{2}\) (1)
where S is the number of tree species and \(P_{i}\) is the proportion of
the number of individuals of species i relative to the total number of
individuals in the community. The Shannon-Weiner index is calculated as
\(H=-\sum_{i=1}^{s}{P_{i}\ln P_{i}}\) (2)
where the meaning of the above parameters is the same as that of formula
(1). The Pielou index describes the evenness of the individual number
distribution among species in an ecosystem and is calculated as
\(J=H/\text{lnS}\) (3)
where H is the Shannon-Weiner index and S is the number of species.