Augalijos raida Talšos ežero apylinkėse per pastaruosius 14 000 metų
The reconstruction of the post-Glacial vegetation changes and their magnitude is based on a new data (geological-geomorphological survey, pollen, plant macrofossil and 14C date) obtained from Talša Lake, northern Lithuania. The Talša Lake lies in the deepest part of the typical tunnel-valley of subg...
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| Format: | Master Thesis |
| Language: | Lithuanian English |
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Institutional Repository of Vilnius University
2009
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| Online Access: | https://repository.vu.lt/VU:ELABAETD2045279&prefLang=en_US |
| Summary: | The reconstruction of the post-Glacial vegetation changes and their magnitude is based on a new data (geological-geomorphological survey, pollen, plant macrofossil and 14C date) obtained from Talša Lake, northern Lithuania. The Talša Lake lies in the deepest part of the typical tunnel-valley of subglacial type crossing the marginal formations of the Late Weichselian Glaciation. Multiple sediment cores of 7,18 m depth consisting of limnic and biogenic sediments were obtained from the northwestern part of the Talša Lake (55°56¢53²N, 23°20¢19²E, 103 m a.s.l.). The chronology of identified post-Glacial vegetation variations is based on the results of 14C dating and biostratigraphical information. The time scale was constructed on the basis of linear interpolation between calibrated 14C dates (the midpoint of the ±2σ) and regionally dated limits of chronozones. Before 13700 cal BP area was covered with tundra-type herb vegetation with the patchy occurrence of Betula and possibly Pinus. Such vegetation is typical of a cold and dry climate. Terrigenous sediments were settling in the lakes. The palaeobotanical record indicates a continuing forestation of the region with open Pinus forest during 13700 cal BP–12600 cal BP. Thermokarst processes and solifluction took place. Climate was warmer and more humid. Climate cooling resulted in a significant reduction in tree cover contemporaneous with the formation of an open, herb-grass dominated landscape, and low water levels during the period 12600 cal BP–11000 cal BP. After 11000 cal BP expansion of light Betula predominated forest took place, water level in the lake being low. The further development of the vegetation composition indicates flourishing of the pine-predominating forest that continued until about 10250 cal BP-9600 cal BP. Lake water level was still low. Gradual immigration of the deciduous trees e.g. Ulmus and Corylus was recorded at the same time. Differentiation of forests was growingly manifested before 8900 cal BP-7800 cal BP. Pine prevailed in Talša lake, ... |
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