Reconstruction of the past 3000 years of vegetation and land-use dynamics : a case study of pollen and geochemical indicators of Lake Lavijärvi in Karelian Russia

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http://urn.fi/URN:NBN:fi-fe201804208683
Title: Reconstruction of the past 3000 years of vegetation and land-use dynamics : a case study of pollen and geochemical indicators of Lake Lavijärvi in Karelian Russia
Author: Fatemeh, Ajallooeian
Contributor: University of Helsinki, Faculty of Science, Department of Physics
Publisher: Helsingin yliopisto
Date: 2018
Language: eng
URI: http://urn.fi/URN:NBN:fi-fe201804208683
http://hdl.handle.net/10138/273487
Thesis level: master's thesis
Abstract: Pollen samples from Lake Lavijärvi (sediment core LAV16-05) located in western Karelian Russia were examined. 21 pollen and spore types were identified in the process to reconstruct the past ~3000 years vegetation cover and consequently understand major climate pattern of the area. The pollen diagram was divided into 4 zones determined by the main vegetation changes: Zone A (2700 to 1400 cal BP or 750 BC to 550 AD) representing a consistent arboreal forest; Zone B (1400 to 650 cal BP or 550 to 1300 AD) demonstrating a transition from forest to forest-steppe vegetation; Zone C (650 to 10 cal BP or 1300 to 1940 AD) illustrating fluctuations of vegetation patterns; and finally, Zone D (10 to -66 BP or 1940 to 2016 AD) showing the recent post-war relaxation of land-use. Pinus, Picea, Betula, Alnus, Chenopodiaceae and Poaceae are among the major pollen types. Throughout the core changes in vegetation patterns and slash and burn cultivation are well represented. The Medieval Warm Period and the Little Ice Age are also moderately present in the pollen frequency and variety. The anthropogenic effects of farming are displayed by large abundances of Poaceae and Cerealia pollen especially in Zone C, eutrophication of the lake and the absence of Picea pollen due to fires. Today, the lake’s surrounding is mainly pasture with arable farming taking place moderately. The climate of Lavijärvi appeared to have had long winters with excessive snow cover especially in the early stages (2600 to 1000 cal BP or 650 BC to 950 AD) and a moderately dry temperature due to Chenopodiaceae growth though maintaining enough soil moisture for cultivated plants. Other geochemical indicators such as TIC, TN and C/N of core LAV 16-05 were measured. The geochemical findings represent a silt loam sediment profile for the core along with an organic rather than inorganic carbon available together with steady yet low levels of TN and TS. Lake Lavijärvi is a good example of shifting from dense arboreal forest to steppe-like vegetation and finally pasture throughout a window of 3000 years and can reveal useful information on the land-use history of the area.


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