Vegetation sensitivity to climate changes and human impact in the Harghita Mountains (Eastern Romanian Carpathians) over the past 15 000 years

摘要

Although few compared with Western Europe, continental records from Central-Eastern Europe are increasingly confirming that rapid climate fluctuations of the past 15 000 years are also present in records situated far from the North Atlantic region. In the present study a new pollen record supported by 11 AMS 14C dates, from Luci (Eastern Romanian Carpathians), was used to reconstruct the Lateglacial and Holocene vegetation history of the region, and the sensitivity to past climate change and human impact. The results showed that vegetation composition reacted particularly sensitively to the climatic oscillations that occurred during the Aller?d (13 800 cal a BP), the Younger Dryas (YD) and at the transition from the YD to the Holocene (11 700 cal a BP), although smaller amplitude vegetation changes also occurred at ca. 14 700 cal a BP (Greenland Interstadial (GI)-1e; B?lling), 13 900 cal a BP (GI1-d; Older Dryas) and 13 200 cal a BP (GI-1b; intra-Aller?d cooling). However, the amplitude of vegetation response in the continental part of Europe was smaller as compared with the records from Greenland and the North Atlantic region. The Holocene began with the expansion of Betula, Ulmus and Picea abies, followed by Fraxinus, Quercus, Tilia and Corylus avellana from about 10 000 cal a BP when the climate became warmer and drier. Picea abies has been the dominant tree species for almost the entire Holocene period. The spread of Carpinus betulus occurred at ca. 5800 cal a BP, with maximum values between 5100 and 3100 cal a BP, while Fagus sylvatica spread at ca. 3100 cal a BP and attained maximum values between 2800 and 200 cal a BP. However, during the last 200 years, Fagus sylvatica and Picea abies forests have largely been replaced by Pinus. Human impact in the area is noted from ca. 4200 cal a BP onwards but it is expressed rather weakly until 1200 cal a BP, and primarily relates to forest clearance and grazing.