Holocene succession and biogeographical importance of mollusc fauna in the Western Sudetes (Czech Republic)

The location of the Sudetes Mts. between the Alpine and Scandinavian ice-sheets during the Quaternary Period makes this area interesting from a biogeographic point of view. Little information was known about the Holocene mollusc and vertebrate fauna of this area up to now. Despite some regional differences among particular mountain areas, it seems that Sudetes Holocene mollusc succession follows a similar but moderate course to that of the standard central European Holocene succession. The Stárkov-Vápenka sequence can be used as a standard succession pattern for this area. Some woodland species can survive the Glacial in talus slope debris with suitable microhabitats (e.g. Oxychilus depressus). The structure of the vertebrate assemblage suggests that the valleys of KrkonoÅ¡e Mts. might provide favourable conditions for a diversified mammalian community and could take the role of a glacial refugee. This study indicates that isolated occurrences of Alpine and Carpathian elements, such as Cochlodina dubiosa corcontica endemic in KrkonoÅ¡e Mts., are not relics of a former, much wider distribution, but modern immigrants of the younger half of the Holocene and thus its spreading was very slow. It seems that the Western Sudetes Mts. (except for the JeÅ¡těd Ridge) were an island of low mollusc diversity, not human-induced but natural, during the whole Holocene.