Record of environmental changes during the Holocene in the light of malacological studies of river sediments in the Łapszanka Stream valley (Spisz area, Carpathians, Southern Poland)

The analysis included alluvial sediments in the Łapszanka Stream valley in the Spisz area (Carpathians, Southern Poland). Seven gravel levels were distinguished in the sedimentary sequence, which is a record of periods of intense fluvial activity correlated with wet climate phases. They fall in the Early Holocene (10 100–8900 y BP), the beginning of the Middle Holocene (7900–6600 y BP), the Middle Holocene (6100–5900 y BP), the beginning of the Late Holocene (5100–4000 y BP), the Iron Age Cold Epoch, the Dark Ages Cold Period and the Little Ice Age. The gravels are separated by layers of mud, containing an abundant mollusc fauna. It was possible to distinguish five types of fauna assemblages corresponding to the environmental changes in the Spisz area during the Holocene. The malacofauna indicates that forests covered this area to a large extent during almost the entire period analysed. During the Early Holocene, the area was dominated by coniferous forests, and the fauna contained numerous cold-tolerant taxa. The Middle Holocene saw the emergence of mixed forests inhabited by mollusc communities that included species with high ecological tolerance. A malacofauna containing moisture-loving forest assemblages is characteristic of the sediments of the Late Holocene. The occurrence of muds (agricultural muds) with open-country snails at the top of the sequence indicates increased anthropogenic impact and associated deforestation during the last 500 years.