Mar 17, 2017
Multiplicative beta diversity (gamma/alpha) ranges from 1 to N ( # of sites in the region). Therefore, to get a measure of differentiation independent of the number of sites (N) involved in the calculation, we need to standardize beta diversity. For example, the Sørensen index of dissimilarity is just beta-1 divided by N-1, which ranges between 0 and 1, and is independent of the number of sites (N).
Andrés Baselga, What is Beta Diversity