Climate variability since MIS 5 in SW Balkans inferred from multiproxy analysis of Lake Prespa sediments

The transboundary Lake Prespa (AL/FYROM/GR) has been recognized as a conservation priority wetland. The catchment area has a remarkably diverse flora that points to its refugial properties. A lake sediment core retrieved from a coring location in the northern part of the lake was investigated through geophysical, sedimentological, geochemical, and palynological analyses. Based on tephrochronology, radiocarbon and electron spin resonance (ESR) dating, and cross correlation with other Northern Hemisphere records, the age model suggests that the basal part of core Co1215 reaches back to 92 ka cal BP. Here we present the response of this mid-altitude site (849 m a.s.l.) to climate oscillations during this interval and assess its sensitivity to millennial-scale variability. Endogenic calcite precipitation occurred in Marine Isotope Stages (MIS) 5 and 1 and is synchronous with periods of increased primary production (terrestrial and/or lacustrine). Periods of pronounced phytoplankton blooms (inferred from green algae and dinoflagellate concentrations) are recorded in MIS 5 and MIS 1 and suggest that the trophic state and lake levels underwent substantial fluctuations. Three major phases of vegetation development are distinguished: the forested phases of MIS 5 and MIS 1 dominated by deciduous trees with higher temperatures and moisture availability, the open landscapes of MIS 3 with significant presence of temperate trees, and the pine dominated open landscapes of MIS 4 and MIS 2 with lower temperatures and moisture availability. Forest dynamics, cover and density are discussed in an altitudinal context and the existence of temperate tree refugia is examined.