Non-forest vegetation of Bohemian Basin: relict origin and anthropogenic transformation

A fundamental question for the biogeographical interpretation of central European lowlands is whether the Early Holocene steppe and its biota survived the period of maximum afforestation in the mid-Holocene. So far, our knowledge was limited by the lack of fossil pollen records from dry lowland areas. The scarce analyses of fossil pollen and the more common analyses of molluscs from sedimentary series led to the contrasting interpretations of closed-forest landscape (pollen data) and partly open landscape (mollusc data) in the mid-Holocene. We performed parallel analyses of pollen and molluscs from sedimentary sequences in the dry lowland area along the lower Ohře river in northern Bohemia (Zahájí and Suchý potok). Both analyses provide strong support for the hypothesis of continuous local occurrence of steppe grasslands throughout the Holocene. At the beginning of the Neolithic period this area was probably covered by forest-steppe with pine and birch woodlands supporting many light-demanding species which later found their habitat in secondary grasslands. These secondary grasslands have been developed from ca. 5000 yrs BP due to anthropogenic deforestation and grazing by domestic livestock. For the first time both pollen and mollusc data provide consistent evidence that these grasslands and their biota, although supported and maintained by humans, are a direct continuation of Late Pleistocene and Early Holocene natural steppes.