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  • Author or Editor: Gusztáv Jakab x
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The Sirok Nyírjes-tó peat bog provides an almost full Holocene climatic record reconstructed by bog surface wetness investigations based on plant macrofossil analysis. The method of bog surface wetness reconstruction has not so far been adapted to the characterization of continental peat bogs. The emergence of a deep oligotrophic lake was dated to cc. 9500 cal. yr BP. The driest phase of the peatland was recorded at 6400 cal. yr BP, at the time of the Holocene climatic optimum. The deterioration of the climate, which began at 3500 cal BP, culminates here in the Carpathian Basin, as was shown by numerous records. An increase in the amount of Sphagna from 2800 cal. yr BP in the Nyires-tó peat bog marks the cooling of the climate and the accompanying rise in rainfall. The first oligotrophic Sphagnum peatland developed at Sirok between 2300 and 1500 cal. yr BP. Since 2300 cal. yr BP a record of alternating phases of Sphagnum peatlands and sedge/reed peatlands was demonstrated. A sudden expansion of Sphagna was recorded at least 10 times. Sphagnum-peaks at 2150, 1750, 1300, 1000, 850, 500 and 200 cal. yr BP perfectly match the humid periods identified in western Europe.

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A new quantitative paleobotanical method for the description of Quaternary organic sediments is presented. The Peat Component System, with the paleobotanical description of macroscopic organic material, allowed us to reconstruct the hydroseral succession. The modified "semi-quantitative quadrate and leaf-count macrofossil analysis technique" (QLCMA) was used to quantify the peat components. This quantitative plant macrofossil technique, together with pollen, mollusk, and radiocarbon analyses, was used to reconstruct the postglacial mire development of an eutrophic peat bog in S Hungary. The analysis of the Holocene peat sequence was used to reconstruct the development of a filling-up spillstream of the river Danube. Multiple cores made it possible to reconstruct vegetation development in space and time.

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