Sprecher
Beschreibung
Lateglacial sediments from subalpine lakes in the Rila Mountain (2925 m) were investigated by pollen analysis, radiocarbon dating, macrofossil content and sedimentology. The aims of the study were to: a) reconstruct the flora and vegetation dynamics; b) establish regional radiocarbon chronology; c) define the climate fluctuations and their impact on the vegetation and environment. The sedimentation started 18000-16000 years ago after the retreat of the local glaciers. The lateglacial interval 14,700-11,700 cal. BP was characterized by the alternation of stadial/interstadial phases and the relevant response of the plant cover. The landscape at high-mid altitudes after the termination of the Pleniglacial was dominated by “mountain-steppe” herb communities composed of Artemisia, Chenopodiaceae, Poaceae and other cold-resistant taxa. Isolated stands of Pinus, Betula and shrubland of Juniperus-Ephedra also occurred. The climate improvement during the Bølling/Allerød interstadial initiated afforestation with Pinus, Betula, Alnus, while the herb vegetation partially declined. At lower altitudes deciduous (Quercus, Tilia, Fagus, Corylus) and coniferous (Abies, Picea) trees spread from lateglacial microrefugia where the conditions has favored their survival. The reversal to glacial situation during the stadial Younger Dryas (13,200-11,700 cal. BP) marked the re-advance of the herb communities and a retreat of the tree vegetation. The chironomid-inferred July temperature reconstruction indicated a gradual rise from 8o C at 14,700 cal. BP to 12o C at the transition Lateglacial/Holocene. The palynological results are supported by macrofossil finds of Pinus peuce (needles), Juniperus (stomata) and herbs (seeds). The lateglacial radiocarbon chronology correlates well with the paleoclimate signal from Greenland ice-cores.