Ordination and cluster analysis

Abstract

In ecosystem studies, the ecologist has to face a great number of biotic and abiotic variables linked by a complex net of interrelations which rule the structure and the function of this ecosystem. Defining and describing structural patterns of a ecosystem, as well as formulating hypothesis on its function, requires a multivariate analysis of the data, like classification and ordination. This exposition aims a simple description of these techniques and comments on some important points for an adequate use. A criterions choice of the similarity index must be done, depending on the nature of data and the objective of the work. Different cluster and ordination methods are listed with comments. Advise on reading dendrogram and factorial plans and interpreting results is introduced.