Janus Pannonius Múzeum Évkönyve 43 (1998)( Pécs, 1999)

Természettudományok - Dénes Andrea–Ortmanné Ajkai Adrienne: A Dráva baranyai holtágai. Általános és botanikai jellemzés, természetvédelmi kérdések

26 A JANUS PANNONIUS MÚZEUM ÉVKÖNYVE 43 (1998) Oxbow lakes of river Drava in Baranya county (South Hungary). General and botanical description and problems of nature conservation Andrea DÉNES and Adrienne ORTMANN-AJKAI Drava Lowland is a varied landscape, rich in diverse habitats, one of the greatest wet lowlands of Hungary. As a consequence of high level of groundwater and yearly precipitation it is very rich in wetland habitats. 46 oxbow lakes (belonging to 21 settlements) represent significant natural values, but have serious nature conservation problems too. These oxbow lakes, with their marsh and moor plant communities, protected and rare species (Thelypteris palustris, Hottonia palustris, Urtica kioviensis, Utricularia minor, Ranunculus lingua, Carex elongata, C. elata, C. pseudocyperus, С vesicaria, Cardamine amara, Salvinia natans, Nymphoides peltata, Trapa natans, Nymphaea alba, Fontinalis antipyretica, Ricciocarpus natans, Wolffia arrhiza, Polygonum amphibium, Stratiotes abides, Riccia fluitans, Leucojum aestivum, Caltha palustris, Equisetum palustre, E. telmateia, E. hyemale) are last remnants of former unbroken wetlands. In meliorated regions presence of water itself has a high value. Oxbow lakes are endangered by many disturbing factors, e.g. angling with all its consequences, pollution caused by cultivation of neighbouring fields, invasion of adventive species, and succession (both natural and quickened-up by organic pollution). After regulating of Drava new oxbows cannot be born, but existing ones will be filled up completely in an interval comparable with human lifetime. Authors' address: DÉNES Andrea Natural History Department Janus Pannonius Múzeum P. О. Box 347. H-7601 Pécs ORTMANN-né AJKAI Adrienne Báránytetó 2. H-7635 Pécs