The composition and richness of Danubian floodplain forest land snail faunas in relation to forest type and flood frequency

Abstract

The species richness and composition of land snail assemblages in 42 floodplain forest sites along the Danube River in Slovakia were studied to find the main ecological gradients responsible for the variation in the faunas. We found just one, but steep, ecological gradient influencing the variation of snail species composition among different floodplain forest types, reflected in the first detrended correspondence analysis axis, which explained 29.6% of total variation. Site scores on this axis were significantly correlated with site humidity (rs=-0.868; P<0.001). Significant loading on the first axis was also found for flood frequency and several vegetation descriptors. Species composition mainly reflected differences between sites without floods and the others. Species richness as well as total abundances of live individuals were not significantly controlled by any explanatory variable, although some trends could be discerned. Considering vegetation classification, substantial differences were observed between wet softwood floodplain forests and the remaining types, drier softwood forests and different types of hardwood forests, which were impossible to distinguish based on land snail assemblages. The results are discussed in relation to earlier descriptive studies, and in terms of the conservation of these threatened habitats. © The Author 2007. Published by Oxford University Press on behalf of The Malacological Society of London, all rights reserved.