Time-transgressive early Holocene vegetational succession following shore displacement: a case study from central Sweden |
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| Authors: | MIKAEL BERGLUND |
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| Institution: | Department of Natural Sciences, Mid Sweden University, SE-851 70 Sundsvall, Sweden |
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| Abstract: | Deglaciation took place in eastern Jämtland and Ångermanland in central Sweden c . 10 500–10 200 cal. yr BP. In the present study, vegetation development and shore displacement during the earliest ice-free period are investigated by 14C dating of sediment from six isolated lake basins and by pollen analysis. A brief but distinct peak in Hippophaë occurs in all pollen diagrams coincident with basin isolation, followed by up to 500 years (varying locally) by an Alnus rise. The Alnus curve does not display a synchronous rise in the area. Its expansion below the highest shore level is time-transgressive and controlled mainly by the timing of basin isolation. The relationship between regional Alnus expansion and changes in hydrology and climate is discussed. The pollen diagrams show Pinus predominance with Corylus to the east (more coastal areas) and Betula predominance (though less pronounced) to the west during the period 10 200–9000 cal. yr BP. However, comparisons between sites suggest marked variability in the forest development. Shore displacement in easternmost Jämtland c . 10 300–9000 cal. yr BP is equal to or slightly more rapid than that of SE Ångermanland, contrary to the present pattern of isostatic recovery. A rapid shore level regression c . 10 300–10 000 cal. yr BP may be related to drainage of the Ancylus Lake. |
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