Holocene paleoecology along the Blekinge coast, southeast Sweden, and implications for climate and sea-level changes

To investigate the Holocene vegetation history and shoreline displacement along the southeastern Swedish coast, two radiocarbon dated pollen, macrofossil, and mineral magnetic sequences were studied in the western Blekinge coast: Hunnemara Lake and Smygen Bay. Both pollen records show mosaic vegetation with grasslands, heaths and woodlands prior to 11,300 cal. BP. Pinus-dominated mixed forest was initially established by 11,000 cal. BP. By 10,000 cal. BP, mixed forest with higher species diversity was fully established. Expansion of broad-leaved trees began at about 8,600 cal. BP, indicating the onset of the mid-Holocene thermal maximum in Scandinavia. Following the Ulmus decline ~5,800 cal. BP, the regional forest became much more open due to increased human disturbance. Both basins were isolated during the period of 11,300–11,000 cal. BP, and subsequently in contact with the Ancylus Lake between 10,700 and 9,800 cal. BP. Low abundance of brackish-water diatoms at Smygen suggests that this basin was connected with the Baltic Sea between 9,800 and 8,600 cal. BP, corresponding to the Early Littorina Sea phase. Hunnemara was isolated during this period. The two basins were in turn flooded at 8,600 and 8,300 cal. BP, as a result of global sea-level rise. A sedimentary hiatus (8,300–7,500 cal. BP) was present at Hunnemara, probably caused by a rapid sea-level rise related to global meltwater pulse 3. Aquatic macrofossil and mineral magnetic proxies reveal several minor transgressions at both sites, probably regulated by centennialscale variations in regional storminess Hunnemara was isolated from the Baltic Basin by 3,100 cal. BP, concurrent with a lowering of the sea level at Smygen.