OLIGOCENE FLORA OF BECHLEJOVICE AT DĚČÍN FROM THE NEOVOLCANIC AREA OF THE ČESKÉ STŘEDOHOŘÍ MOUNTAINS, CZECH REPUBLIC

The laminated diatomite of Bechlejovice in the suburbs of Děčín from the area of the České středohoří Mountains, northern Bohemia, has become a world-known palaeontological site of Tertiary frogs. It is now evaluated in respect of the flora and vegetation based on plant macrofossils. Also the so far accomplished explorations in palaeontological, geological and geochemical research are reviewed. The plant macrofossil record includes a bryophyte, two ferns (Polypodium, Rumohra), a cycad (? ), a single conifer (Torreya) and over 70 angiosperms, of which Mahonia pseudosimplex sp. nov., Tilia brassicoides (SAPORTA) comb. nov., Zelkova zelkovifolia (UNG.) BŮŽEK et KOTLABA forma bechlejovicensis forma nov., Rosa milosii sp. nov., Leguminosites cladrastioides sp. nov. and Ziziphus ziziphoides (UNG.) WEYL. forma bilinica (ETTINGSH.) stat. nov. have been newly established. Noteworthy elements, such as Platanus schimperi (HEER) SAP. et MAR., Sterculia crassinervia (ETTINGSH.) PROCHÁZKA et BŮŽEK, cf. Matudaea menzelii WALTHER, Haemanthophyllum sp. , Diospyros brachysepala A. BR. , cf. Pyracantha kraeuselii WALTHER, Ailanthus prescheri WALTHER, Dicotylophyllum deichmuelleri Z. KVAČEK et WALTHER, D. heerii (ENGELH.) Z. KVAČEK et WALTHER, and Arecaceae gen. et sp. have been newly recorded at this site. Vegetation reconstruction of this local macrofossil assemblage presumes only a narrow belt of aquatic herbs (“Typha”, Haemanthophyllum) rimming the lake. A mixed mesophytic broad-leaved forest with a small proportion of thermophilic elements (Lauraceae, Platanus neptuni (ETTINGSH.) Z. KVAČEK et al., cf. Quercus bavarica (KNOBLOCH et Z. KVAČEK) Z. KVAČEK, ? Sloanea artocarpites (ETTINGSH.) Z. KVAČEK et HABLY, Arecaceae gen. et sp. ), well developed shrubs (? Zamiaceae gen. et sp., Rosa, Mahonia, Ziziphus, Ampelopsis) and herb undergrowth (Rumohra recentior (UNG.) BARTHEL, Polypodium radonii Z. KVAČEK, Monocotyledonae gen. et sp. ) vegetated on the raised habitats around the lake on the fertile volcanogenic soils. Judging from the frequency of leaf impressions, the canopy and smaller tree storeys of the forest were dominated in close proximity of the lake by various hamamelids, such as Cercidiphyllum, Juglandaceae (Carya, Cyclocarya), Betulaceae (Alnus, Ostrya, Carpinus) and other woody elements, such as Craigia, Tilia, Ulmus, Zelkova and various species of Acer. The legumes, Populus, Rosaceae, Toxicodendron, Ampelopsis, Smilax and some more, partly enigmatic angiosperms represented minor accessory admixtures nearby the site. Palynological data inform us that this characteristic covers only a narrow section of the landscape, while additional conifers (including Pinaceae and Cupressaceae) and broad-leaved woody plants (including Engelhardia) were represented in wider environs. The Early Oligocene age of Bechlejovice is estimated in view of the presence of ancient Palaeogene elements (Boehlensipollis hohlii, Platanus schimperi, Sterculia crassinervia, Haemanthophyllum) and the correlation with the radiometrically dated level at Roudníky near Ústí nad Labem with umbrid fish and a similar flora. Both sites belong to the lower part of the volcanic complex characterised by older olivine-rich basalts (Ústí Formation sensu Cajz). Flora and vegetation, Early Oligocene, northern Bohemia, volcanic setting. Received April 7, 2004