NEOBIOTA 2010 Conference Biological Invasions in a Changing World - from Science to Management Invasive alien fern-taxa in north-western Germany Peter Keil 1 , Andreas Sarazin 2 ,Renate Fuchs 3 , Corinne Buch 1 , Peter Gausmann 3 1 Biologische Station Westliches Ruhrgebiet e. V., Ripshorster Straße 306, 46117 Oberhausen; peter.keil@bswr.de 2 Heinickestraße 47, 45128 Essen; andreas.sarazin@gmx.de 3 Ruhr-Universität Bochum Geographisches Institut, AG Landschaftsökologie, Universitätsstr. 150, 44780 Bochum; renate.fuchs-mh@t-online.de Sphagnumgausmann@web.de Abstract Within the last 20 years, the fern flora of northwest Germany has undergone striking changes. Compared with flowering plants, neophytic fern species are rarely found in Germany. In addition to an area expansion of some indigenous species like Asplenium adiantum-nigrum, Asplenium scolopendrium, Dryopteris affinis s. l. and Polystichum aculeatum (s. KEIL et al. 2009) – originally found only in the low mountain range, now spread far into the northern German lowlands – more and more findings of neophytic fern species were simultaneously observed, species that had not been known from the lowland area or that had been known only from a few locations, for example Azolla filiculoides (DÜLL & KUTZELNIGG 1987) and Onoclea sensibilis (FUCHS & KEIL 2004). Starting a few years ago in the Ruhr area and in Rhineland, findings of subtropical fern species were observed in cellar light shafts and in wells, as well as on walls, species that until then had only been grown as greenhouse plants, for example Adiantum capillus-veneris, Adiantum raddianum and Pteris cretica var. albo- lineata. The newest examples of additional neophyte fern species are Pteris multifida, Pteris cretica s. str. Cyrtomium fortunei var. clivicola and Selaginella kraussiana (SARAZIN et al. in press., compare Tab.1). While in the Atlantic-influenced climatic region of Europe where these fern species have been found for many years (z. B. EDGINGTON 2008, VERLOOVE et al. 2007), in Germany most of them were only detected in the past 5 years. References DÜLL, R. & H. KUTZELNIGG (1987): Punktkartenflora von Duisburg und Umgebung. 2. Aufl., Rheudt (Verlag IDH). 378 S. EDGINGTON, J. 2008: Urban ferns. – Pteridologist 5: 5-7. FUCHS, R. & KEIL, P. 2004: Onoclea sensibilis L. – der Perlfarn im Duisburg-Mülheimer Wald (Westliches Ruhrgebiet, Nordrhein-Westfalen). – Florist. Rundbr. 37: 103-107.