Vegetation and climate history of the Lake Prespa region since the Lateglacial

摘要

Pollen assemblages of a sediment sequence (Col215) from Lake Prespa reveal substantial vegetational and environmental changes on a regional scale for the Lateglacial and Holocene. The age-depth model, based on radiocarbon dating and tephrochronology, indicates continuous sedimentation for the last c. 17 000 cal BP. An open landscape with prominent cold-resistant steppe vegetation and isolated tree patches (mainly Pinus) is inferred for the Lateglacial. The pollen data suggest the survival of numerous temperate deciduous trees in sheltered and favorable habitats despite the harsh climate conditions. The increase of Pinus and the subsequent drop in herb values both point to the expansion of pines at higher elevations and/or the thickening of their stands during the Bolling/Allered. The coeval rise of oak values and the increase of tree diversity imply rising temperatures and an increase in moisture availability. A reversal to stadial conditions, marked by Artemisia and Chenopodiaceae maxima, characterizes the Younger Dryas chronozone. Climate change during the Early Holocene resulted in the expansion and subsequent diversification of deciduous woodland. The continuous pollen curves of maquis constituents, such as Pistacia and Phillyrea, point to higher mean annual and winter temperatures. An abrupt shortlived reversal, associated with the 8200 cal BP cooling event, was distinguished by a distinct peak of Artemisia percentages. After 7900 cal BP arboreal percentages increased and the Prespa area underwent significant changes in floristic composition. The appearance of crop plant pollen and the increase of weed percentages suggest the intensification of agriculture and can be traced back to c. 2000 cal BP.