Numerical analysis of the order Scorzoneretalia villosae

The Scorzoneretalia villosae (= Scorzonero-Chrysopogonetalia) order was originally defined to describe the sub-Mediterranean grasslands of western Croatia, but its distribution range has since been extended to Albania, Bosnia and Herzegovina, Bulgaria, Italy, Kosovo, Montenegro, Slovenia and Serbia. Major syntaxonomic revisions of the order have been performed at the regional or national scale and show inconsistencies both for the syntaxonomic schemes and relative diagnostic taxa. This situation presents some difficulties in comparing or transferring findings between regions or when using syntaxonomic information for practical purposes. To tackle these inconsistencies, nearly nine hundred relevés already assigned to the Scorzoneretalia villosae were classified with the goal of establishing syntaxonomic relationships among associations. Diagnostic taxa of the main clusters of relevés were identified via Indicator Species Analysis (ISA). Results of statistical analyses were then interpreted from a syntaxonomic standpoint. Associations were ordinated (non-metric multidimensional scaling) on the basis of taxa frequencies in order to visualise their floristic and chorological relationships. Based on the results, associations were grouped within four alliances: Scorzonerion villosae, Chrysopogono-Saturejion subspicatae, Saturejion subspicatae and Centaureion dichroanthae were assigned to two new suborders, the meso-xerophytic Scorzonerenalia villosae and the xerophytic Koelerienalia splendentis, classified within the Scorzoneretalia villosae of the Festuco-Brometea. The order covers the western part of the Balkan Peninsula and, in the northern part of its range, the southeastern portion of the pre-Alpine sectors. Floristic similarities between the Scorzonerenalia villosae and other eastern meso-xerophytic syntaxa of the class have been highlighted. I review the nomenclature for the order, describing or validating two suborders and four associations for the first time, and lectotypifying three syntaxa.