The Abundance-Preference Method for Assemblage Analysis: A Normalized Diagram with Algorithm Implementing the Method

Abstract

This research concerns a graphical method for analyzing species assemblages sampled in an ensemble of different habitats or sites. This approach provides a preference classification of species of an assemblage, combining two parameters in the same graphic, namely the abundance of species and their preferences for habitats, and the preferences are measured using an index adapted from the Shannon formula. In its initial version, this method provided pertinent analyses of assemblages, but it also showed some weaknesses. One weakness concerns taxonomic groups, where the available sampling methods provide only low abundances, generally converted into abundance notes or indices with low values. Therefore, a comparison between assemblages with different demographic strategies is inadequate. This research aims primarily to normalize this graphic method in the hope of minimizing the effect of demographic strategies on measuring the preference. Normalization mainly concerns the format of abundances, for which we propose alternative values that do not affect the other graphic components.