Senglacial och tidigholocen etablering och expansion av lövträd på en lokal i nordvästra Rumänien

Sammanfattning: A sedimentary sequence retrieved from Preluca Tiganului, an overgrown crater lake at 840 m.a.s.l. in the northwest Romanian Carpathian mountains, was investigated by applying pollen analysis, mineral magnetic analysis, loss on ignition and 14C measurements. The purpose of the study was to reconstruct the establishment and expansion of broad-leaved trees during the Late-Glacial and early Holocene and to relate the results to problems associated with glacial refugia and early Holocene migration. The sedimentary sequence extends back to 14700 cal. years BP. Already at this time Pinus (pine) was frequently present. During a warmer period between 13900-12650 cal. years BP a woodland with Pinus, Picea (spruce), and Betula (birch) became established. Around 12650 cal. years BP the vegetation changed and Pinus became again dominant together with Betula, Artemisia (mugwort/wormwood) and Poaceae (grass). At the beginning of the Holocene, 11550 cal. years BP, Ulmus (elm) expanded at the site together with Picea, while the presence of Pinus and Betula decreased. About 700 years later a mixed woodland with Ulmus, Fraxinus (ash), Tilia (lime) and Picea, but also Quercus (oak) and Corylus (hazel) had developed. Corylus expanded in the area and from 9100 cal. years BP the vegetation was composed of a mixed Corylus woodland with the above named broad leaved trees and Acer (maple). This vegetation maintained until 7550 cal. years BP, where the investigations of the core ends. The results suggest that an open Pinus woodland, perhaps with Betula and Alnus (alder), could have been present in the area during the Last Glacial Maximum. Picea and also Ulmus, which are the first to expand at the climatic amelioration, must have had refuges in not too distant areas, perhaps in other places in the Carpathian mountains. Also Fraxinus and Corylus could have been present in the region during glacial time, while Quercus and Tilia seem to have had more distant refuge areas.