Garighe basse a Centaurea subtilis della Murgia Materana (Basilicata)

Low garrigue with Centaurea subtilis Bertol. in the Murgia of Matera (Basilicata). - Centaurea subtilis is an endemism of South East Italy whose distribution range comprises two disjoined areas: Gargano promontory and the Western side of Murge ridge. In Gargano district, C. subtilis charactherizes the chasmophytic communities grouped within an endemic alliance of Centaureo-Campanuletalia (Asplenietea trichomanis). On the other side, in Murge upland, it has abundantly grown in garrigues dominated by sufruticose and fruticose chamaephyte while it is very rare in cliff vegetation. Garrigue communities of Murge were studied using the Zürich-Montpellier School of Phytosociology method with the aim to contribute to a deeper knowledge of the sociological role of C. subtilis along its entire distribution range. These vegetation types, typically on shallow soils overlying the calcareous rock outcrops, were assigned to the association Centaureo subtilis-Thymetum capitati, herewith described for the first time. This latter was subdivided into two subassociations, occurring in different ecological conditions and differentiated by Scabiosa holosericea. Comparing the coenological and bioclimatic features of Murge communities to those of Gargano, considerable differences emerge; these results allow to hypothesize a probable ecotypic differentiation between the two populations.