Numerical syntaxonomy of theAsplenietalia petrarchaein the Iberian Peninsula

A numerical syntaxonomic study of rupicolous vegetation of the Asplenietalia petrarchae in the Iberian Peninsula is described. The study is based on 37 local tables (OSUs) of different rupicolous communities from limestone cliffs found in the eastern half of the Iberian Peninsula. Three classification approaches were followed: (1) ‘hard partition’ techniques, (2) ‘fuzzy partition’ and (3) ordination partition. In order to find a direct solution, we tried an evaluation system based on the inertia associated with a CCA, Canonical Correspondence Analysis, and its relationships with the inertia of a similar CA, Correspondence Analysis. The most effective solutions were found through spatial partitions, and the best partition was obtained with CA considering five segments per axis. Among the fuzzy partitions the best solution was obtained with two clusters and a fuzziness value of 1.20. The best hierarchical partition was Complete Linkage with Chord Distance as a resemblance function. With the GRID procedure applied to the CA diagram, three different groups were distinguished. The first group is related to the Saxifragion boisseriano-reuterani, including five OSUs from Baetic ranges; the second group is very close to the Cosentinio-Lafuenteion rotundifoliae and includes 11 OSUs from thermo-mediterranean areas; the third group, including 21 OSUs basically related to meso-mediterranean areas, is strongly related to the Teucrion buxifolii.