Measuring similarity among plots including similarity among species. An extension of traditional approaches

Aims: Presence/absence coefficients of (dis)similarity are generally based on various combinations of the matching/mismatching components of the classical 2 x 2 contingency table. While a few extensions of the contingency table to species abundance data were proposed, a generalization of such coefficients that includes species resemblances is still lacking. Methods: In this paper we introduce a new family of plot-to-plot (dis)similarity coefficients, which include species abundances and interspecies resemblances in the calculation of the matching/mismatching components of the contingency table. Within this family, the behaviour of five similarity coefficients is examined by graphical comparisons based on simulated data. Conclusions: This new family of similarity coefficients can equally apply to functional or phylogenetic resemblance among species, thus providing a unified framework for comparing species turnover among plots.