Periodic lake-peatland shifts under the Eemian and Early Weichselian climate changes in Central Europe on the basis of multi-proxy studies

• Eemian-Early Weichselian succession in a small kettle hole from Central Europe
• Record of environmental changes influenced by changing climatic conditions
• Tetraedron minimum domination related to bituminous shales in the Middle Eemian
• Development of rich fens during the Late Eemian and Brørup interstadial
• Renewal of the low-productivity lakes during the Herning and Redestall stadials

Long-term palaeoecological sequences dated to the Eemian interglacial and Weichselian glaciation are crucial for understanding cyclic climate changes and ecosystem responses. This article presents a multi-proxy (palaeobotanical, zoological and geochemical) study considering variable aspects of the Eemian-Early Weichselian lake-mire succession in central Poland. The investigated sequence, collected from a former small kettle-hole, revealed many ecosystem alterations, i.e. warm stages led to the terrestrialisation of the lake, whereas stadial coolings to its reappearance. Hence, we examined whether: (i) the Eemian warming influenced the ecological succession of the lake, (ii) lakes which reappeared during the Herning and Rederstall stadial coolings developed alike and (iii) the beginning of peatland functioning (interglacial or interstadial) had an impact on further plant succession. The results show that thermal amelioration during the Eemian interglacial supported domination of Tetraedron minimum and Pediastrum boryanum var. boryanum, which contributed to the sedimentation of bituminous shales. The expansion of Salvinia natans in the final stage of lake existence (Middle Eemian) was probably a result of the mild climate characterised by the lack of late spring frosts. Algae, in contrast to Cladocera, revealed bipartition of the Herning and Rederstall stadials (older sections were colder, younger warmer). However, geochemical and isotopic data point to the very low productivity of the lakes during those stadials. The lake that existed during the Herning stadial revealed very low taxonomical diversity of Cladocera, whereas that during the Rederstall was characterised by relatively high diversity of this group. During the Late Eemian and Brørup interstadial, rich fens with some oligotrophic patches with Sphagnum sp. developed. This study revealed that small water bodies, due to their very local character and often uniqueness of palaeo-records, may be a very valuable source of information about climate and palaeoecology of different groups of organisms during the Eemian interglacial and the Weichselian glaciation.