A Comparison between the Results of the Braun-Blanquet Method and Those of “Cluster Analysis”

Abstract

In deciding on the most suitable method to use in a survey of Irish vegetation, the Braun-Blanquet method was compared with a number of other methods using the same field data.¹ The Braun-Blanquet method is basically a polythetic, sub-divisive method of classification: a set of relevés is divided into two sub-sets depending on the presence or absence of a group of differential species and this process is continued until the eventual sub-sets have an acceptable level of uniformity in their floristic composition. Cluster analysis, developed mainly by numerical taxonomists (Sokal & Sneath 1963) is a polythetic, agglomerative classification, whereby the relevés are grouped on the basis of their overall similarity, and each of these groups are in their turn fused until the whole set of relevés is accounted for.