Preboreal oscillation in the light of multiproxy analyses—Early Holocene in Lake Jelonek (North Poland)

Abstract

In this work, we studied the course of climatic fluctuations at the beginning of the Preboreal period using multiproxy analyses (Chironomidae, pollen, diatoms, Cladocera, stable isotopes, macrocharcoal, microlithofacial) combined with varve chronology of sediments. The results showed a decrease in the mean July temperature and stronger continentalism followed by climate wetting at the start of the Preboreal period. This was reflected in the remodeling of the vegetation cover from birch forests to more open spaces with grass vegetation dominance, as well as that of the species composition of Cladocera and diatoms, and the high variability of isotopic composition. In addition, the results showed the impact of local conditions (fires and relict permafrost) on the amplification of environmental responses due to climate cooling. The environmental transformations presented here correspond temporally to the changes that are well documented in other parts of Europe as the Preboreal Oscillation.

Short-Term Climatic Oscillations in the Central Region of the East-European Plain at the Beginning of the Holocene Based on Palynological Studies of Lacustrine Deposits

“…Chironomid analysis of the Lake Gości ą ż sediments also points to a decrease in temperature during the PBO [18]. Multi-proxy studies of sediments of Lake Jelonek, situated in northern Poland, suggest two phases of cooling during the PBO, as well as a considerable change in terrestrial plant communities, reflected in a replacement of birch woodlands by grass vegetation [19]. The multi-proxy data (pollen, diatoms, Cladocera and 14C) from the sediments of Lake Suchar Wielki in NE Poland indicate three short cold events during the Early Preboreal, with a drop in temperature and a decrease in humidity [20].…”

“…In many pollen records from Poland, an increased percentage of Betula in the older part of the Early Preboreal is registered (e.g., [18][19][20]64]). These changes are usually interpreted as an indication of a temporary decline of pine and the spreading of birch forests as a reaction to the colder and wetter climatic events.…”

“…Kramkowski et al [19] estimated mean July air temperatures (MJAT) in the Preboreal in northern Poland based on the changes in Chironomidae composition in sediments of Lake Jelonek. Two phases of cooling were reconstructed.…”