On the basis of quantitative data (i.e., aAD), species have been classified by means of correlation coefficient and average linkage clustering algorithm, while sample sites have been classified by means of Bray-Curtis coefficient and minimum variance clustering algorithm. Principal Component Analysis (PCA) has been used to identify the main factors influencing the distribution of species over different habitats. PCA depicts components as orthogonal axes, and the relative position of sites on these axes was chosen as a tracer for each component (see ).