PRELIMINARY SUGGESTIONS ON THE PLEISTOCENE PALAEOVEGETATION AROUND THE BISNIK CAVE (CZESTOCHOWA UPLAND, POLAND) BASED ON STUDIES OF MOLECULAR FOSSILS FROM CAVE SEDIMENTS

Bisnik Cave is an important site of Middle Palaeolithic, with the longest sequence of Neanderthal settlement phases in Central Europe. In the previous studies of the Bisnik sediments, different elements of palaeoenvironment in the periods of Neanderthal occupation have been recognised, except of palaeovegetation, which could not be derived because of lack of preserved plant micro- or macrofossils. The current work is an attempt to reconstruct palaeovegetation in vicinity of the Bisnik Cave, using analysis of composition of plant-derived n-alkanes, preserved in sediments. In our study, we analyzed one sample from each of the sediment's layers 11 - 19c (early Late Pleistocene and late Middle Pleistocene). Abundant n-alkanes (mostly n-C-27, n-C-29 and n-C-31) were found in all the sampled layers except for the layers 12, 16 and 19d, showing no alkanes at all. There is clear diversification of n-alkanes composition and CPI (carbon preference index) values between layers. Analysis of this composition, allows us to claim that the layers 11 and 14 were accumulated when the cave's vicinity was covered by dense coniferous forests, hence upon warm climate. The layers 19, 19a lower, 19b and 19c, presumably originated during cold periods when open woodlands or grasslands dominated. The other analyzed layers could be connected with intermediate vegetation in form of open woodland. However, not all of the achieved results stay in compliance with the actual stratigraphy, established basing on lithological data and palaeoecology of fossil fauna, and we hope that explanation of this discrepancy would be possible after more extensive studies of molecular fossils are done.