Could canopy forests survive agricultural colonization in the polabi lowland (czech republic)

Abstract

The Polabi lowland is one of the most important agricultural areas in Central Europe. Since the Neolithic Age, agriculture has prevented full expansion of the mixed deciduous forest. We studied the succession of molluscan assemblages and/or fossil pollen in this area to answer the question as to how long the canopy forest could survive ongoing human impact. Environments suitable for the fossilization of these two fossil types differ, and the joint occurrence of both is rare. However, the 0.75 m deep profile of alluvial loams and clays situated in the irregularly inundated floodplain area of the Dubanka stream yielded material rich in both mollusc shells and pollen. Very rich molluscan assemblages occur only in a 45 cm thick layer, which was dated using the AMS radiocarbon method to the Bronze Age (1796-1258 BC). The molluscan assemblages consist of continuously occurring rare deciduous woodland species (such asDiscus perspectivus, Platyla polita, Cochlodina orthostoma, Ruthenica filograna) and species of relict wetlands (e.g. Perpolita petronella, Vertigo angustior, V. antivertigo, Vallonia enniensis). Pollen analyses also suggest the presence of wetland assemblages, with a huge proportion of alder in the central part of the succession followed by willow. The deciduous forests consist of elm (Ulmus), oak (Quercus), lime tree (Tilia), maple (Acer) and hazel (Corylus). Pollen grains of spruce (Picea), white fir (Abies) and beech (Fagus) confirm the late Holocene age of the profile. These results provide evidence of a woodland and wetland mosaic which still covered this landscape during the Bronze Age, in contrast with the present-day monotonous open lowland. © Czech Geological Survey.