Late Glacial and Early Holocene development of lakes in northeastern Poland in view of plant macrofossil analyses

Abstract

The Late Glacial history of the development of seven extant or former, now sediment-filled, lakes in northeastern Poland was investigated based on high-resolution plant macrofossil analyses and AMS radiocarbon dating. According to palaeobotanical data and AMS dating, the accumulation of organic sediments began during the Bölling period. The bottom sediments of all studied lakes contain plant macrofossils typical of Late Glacial vegetation, such as Betula nana, Dryas octopetala, Potamogeton filiformis, and Potamogeton alpinus. The first plants to occur in the lakes were Chara sp., P. filiformis and Batrachium sp. The Late Glacial sediments included rarely encountered macrofossils of Sphagnum teres. At the beginning of the Holocene, the water level in the studied northeastern Polish lakes decreased significantly. This was manifested in a change in the type of sediment, transformation of small lakes into peatland in places, and expansion of typical (indicator) plants of shallow waters.