FLORISTIC INVESTIGATION OF QUERCUS CERRIS AND QUERCUS FRAINETTO COMMUNITIES IN BULGARIA

The present research is a part of the investigations over the structure of mixed forest communities of Quercus cerris and Quercus frainetto in Bulgaria. The investigated communities are typical for Habitat 91I0 - Euro-Siberian steppic woods with Quercus spp., and Habitat 91MO - Pannonian-Balkanic turkey oak-sessile oak forests. The floristic composition of about 100 described plant communities is defined. According to the geobotanical zoning they refer mainly to the European broad-leaved forest district and the Lower Danube province of Eurasian steppic and woodsteppic district. About 598 species of vascular plants and about 24 species of bryophytes have been established during the investigation. The life forms (according to Raunkier) and the floral elements (according to Assyov et al.) for the vascular plants have been determined. Over 60% of the species refer to the families Asteraceae, Fabaceae, Poaceae, Rosaceae, Lamiaceae, Caryophyllaceae, Scrophullariaceae and Liliaceae. In the species composition the participation of the Eur-Asian, Eur-Mediterranean, subMediterranean, Eur-Siberian and the European floral elements is bigger. The life form Hemicryptophyte clearly predominates. A comparative floristic analysis with published data for the investigated communities has been made.