Syntaxonomy of Pinus nigra s.l. communities in the Erico-Pinetea class and their distribution in the central Apennines and Balkan province.

The aim was to study the relationships among forest communities dominated by Pinus nigra s.l. in the Apennine-Balkan biogeographical province. The opportunity to deepen this argument was offered by Pinus nigra natural communities present in the central Apennines (Gran Sasso d'Italia). The data collected on the vegetation were elaborated with the phytosociological method, although in the choice of the higher order syntaxa, it was considered appropriate to broaden the approach to different tectonic, palaeobotanical, palaeogeographic and biogeographic analysis factors, to define the classes and reference orders. This led to the recognition that the black pine forests of the study area, together with those of the central-southern limestone Apennines, should be included in the class Erico-Pinetea Horvat 1959. For the territory investigated, we describe the new association Junipero hemisphaericae–Pinetum nigrae and the new order Junipero communis–Pinetalia nigrae ordo nov. hoc loco, of which the southern Balkan alliance Fraxino orni-Pinion nigrae Em 1978 is considered the alliance typus. In this context, the new alliance Junipero hemisphaericae–Pinion nigrae (typus: Junipero hemisphaericae–Pinetum nigrae) represents the central-southern Apennine vicariant. The new order Junipero communis-Pinetalia nigrae represents the vicariant of the order Erico-Pinetalia Horvat 1959 in the central-southern Apennine-Balkan mountain ranges. [ABSTRACT FROM AUTHOR]