Differences in pollen and macrophytic remains in sediments from various depths in a small kettle-hole lake in southern Finland |
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| Authors: | MIRJAMI TOLONEN |
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| Institution: | Mirjami Tolonen, University of Helsinki, Department of Botany, Unioninkatu 44, SF-00100 Helsinki |
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| Abstract: | Stratigraphical analyses from four locations within the same lake revealed differential dispersal of pollen in sediment, and horizontal movement and focusing of sediment, but revealed only slight differences in pollen and macrofossil assemblages. Between 9,000 and 8,000 B.P., organic sediments focused into the central depth of the basin and no sediment accumulated in the littoral sites in water < 7.5 m deep. From around 5,000 to 4,500 B.P., deposition took place more or less continuously at all four sites. After 1,600 B.P., the marked change in lithology is due to a heavy rise in organic and minerogenic input from the unforested watershed. The littoral cores show that not only does the water depth cause rcdeposition and focusing of sediment, but also the morphometry of the basin. The comparison between macrofossils and pollen, both produced primarily by the same vegetation around the lake, confirmed the reconstruction of local environmental short-term changes which occurred after the clearance of forest vegetation by man. |
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