Lateglacial and early Holocene environmental changes in northeastern Lithuania

Abstract

Multiproxy data (pollen, diatoms, plant macrofossils, 14C and loss on ignition measurements) obtained from two cores (Petrašiūnai and Juodonys) were used to reconstruct the pattern of Lateglacial and early Holocene environmental changes in NE Lithuania. The flourishing of open Pinus forest and presence of light-demanding taxa on poor unstable soils surrounding shallow water basins have been recorded from about 13,100–13,000 cal BP to 12,600 cal BP in the study area. After 13,000 cal BP, expansion of Betula dominated vegetation and increased abundance of cold-tolerant plants together with a simultaneous drop of water temperature indicates a short climate deterioration, tentatively correlated with the “Gerzensee oscillation”. A sudden reduction of the forest cover and extensive development of grass-herb dominated landscape is suggestive of a regional expression of the Younger Dryas cooling, dated to 12,600–11,500 cal BP. Climate aridification resulted in a progressive lowering of the water level and subsequent overgrowth of the basins. Early Holocene vegetation changes show a pattern of forest development with dominance of spruce shortly after 11,500 cal BP. Based on palynological evidence and the presence of plant macrofossils (seeds and needles), early Holocene immigration of Picea sp. to Juodonys (9410 ± 310 BP; Vs-1433) and Petrašiūnai (9420 ± 65 BP; TUa-6177 (DF2471)) is indicated. Further development of the vegetation cover indicates multiple flourishing of predominant open birch vegetation subsequently followed by pine-spruce forest development caused by Preboreal climate instability. The most prominent climate shift, e.g. drop of the temperature and humidity recorded shortly before 11,100 cal BP has been correlated with the “Preboreal Oscillation” (Björck, S., Rundgren, M., Ingolfsson, O., Funder, S., 1997. The Preboreal oscillation around the Nordic Seas: terrestrial and lacustrine responces. Journal of Quaternary Science 12, 455–465). Expansion of birch-predominant forest around shallow water basins has been identified during the Late Preboreal, after 11,100 cal BP.