Application of the pollen data to the reconstruction of palaeoenvironmental and climatic variations: investigation of the ULA-2 outcrop

The main aim of the investigations conducted was to analyse lateglacial environmental changes in south-eastern Lithuania. Multidisciplinary methods (pollen, LOI, carbonate analysis, isotope 14C (AMS)) were applied to organically enriched deposits, covered with the aeolian sand, in the outcrop located on the left bank of Ula River, the left tributary of Merkys River (54º06´34,1´´N, 24º28´44,4´´E). The data collected, including the results of radiocarbon dating from Poznan Radiocarbon Laboratory, indicate that sedimentation started at the beginning of lateglacial interstadial, the warmest period of the investigated Lateglacial interval. Deposition of the gyttja started at about 15200–14650 cal. yr BP, or during GI-1e event (Lowe et al. 2008), and was interrupted at 13630–13300 cal. yr BP, during the GI-1b event. Pollen data show that Betula predominated forests with the grasses enriched with? underwood existed during the GI-1e climatic event, when the amount of organic matter in the sediments increased. Later, an increase in Pinus representation is observed. Approaching the upper part of sediments, some instability in the pollen diagram is seen. Abundance of the cold-tolerant plants suggests colder and dryer climate which determined a thinning of the forest cover and expansion of different herbs. According to our new data these sediments were deposited during the GI-1b or Gertsenzee climatic event. Infilling of this sedimentation basin ended during this climatic event, much earlier than previously thought