Thermophilous deciduous forests in Southeastern Europe
This paper deals with the numerical elaboration of the database of 1764 relevés of thermophilous deciduous forests assigned by the authors to the order Quercetalia pubescentis in the northwestern part of Southeastern Europe. After elimination of relevés which were dominated by mesophilous deciduous and coniferous tree species, the stratification of relevés was carried out. The TWINSPAN classification revealed eight ecologically and phytogeographically interpretable groups. Additionally the analysis of Pignatti indicator values passively projected on the PCA diagram of the eight groups, and a chorological analysis of individual groups were made. The analyses revealed that all groups in general match with the traditionally accepted alliances, such as Quercion pubescenti-sessiliflorae, Aceri tatarici–Quercion, Quercion confertae, Quercion petraeae-cerris, Syringo-Carpinion, Pruno tenelle–Syrinion, Carpinion orientalis and Fraxino orni–Ostryion. Finally, a synsystematic classification of the elaborated group is proposed, and the nomenclature is harmonised with the International Code of Phytosociological Nomenclature. The results are also presented in a synoptic table together with calculation of the diagnostic species.