Pollen-based paleoenvironmental and paleoclimatic change at Lake Ohrid (SE Europe) during the past 500 ka

Abstract

Abstract. Lake Ohrid is located at the border between FYROM and Albania and formed during the latest phases of Alpine orogenesis. It is the deepest, the largest and the oldest tectonic lake in Europe. To better understand the paleoclimatic and paleoenvironmental evolution of Lake Ohrid a deep drilling was carried out in 2013 within the framework of the Scientific Collaboration on Past Speciation Conditions (SCOPSCO) project that was funded by the International Continental Drilling Program (ICDP). Preliminary results indicate that lacustrine sedimentation of Lake Ohrid started between 1.2 and 1.9 Ma ago. Here we present new pollen data (selected percentage and concentration taxa/groups) of the uppermost ~200 m of the 569 m-long DEEP core drilled in the depocenter of Lake Ohrid. The study is the fruit of a cooperative work carried out in several European palynological laboratories. The age model is based on nine tephra layers and on tuning of biogeochemical proxy data to orbital parameters and to the global benthic isotope stack LR04. According to the age model the studied sequence covers the last ~500 000 years at a millennial-scale resolution (~1.6 ka) and record the major vegetation and climate changes that occurred during the last 12 (13 only pro parte) marine isotope stages (MIS). Our results indicate that there is a general good correspondence between forested/non-forested periods and glacial/interglacial cycles of marine isotope stratigraphy. Our record shows a progressive change from cooler and wetter to warmer and dryer interglacial conditions. This shift is visible also in glacial vegetation. The interglacial phase corresponding to MIS11 (pollen assemblage zone, PAZ OD-12, 488–455 ka BP and OD-19, 367–328 ka BP) is dominated by montane trees such as conifers. The two younger interglacial periods, MIS5 (PAZ OD-3, 126–70 ka BP) and MIS1 (PAZ OD-1, 12 ka BP to present) are marked by dominance of mesophilous elements such as deciduous and semi-deciduous oaks. Moreover, MIS7 (PAZ OD-6, 245–189 ka) shows a very high interglacial variability, with alternating expansions of montane and mesophilous arboreal taxa. Grasslands (open vegetation formations requiring relatively humid conditions) characterize the first glacial phases of MIS12 (PAZ OD-12, 488–455 ka), MIS10 (corresponding to PAZ OD-10, 421–367 ka) and MIS8 (PAZ OD-7, 285–245 ka). Steppes (open vegetation formations typical of dry environments) prevail during MIS6 (OD-5 and OD-4, 189–126 ka) and during MIS4–2 (PAZ OD-2, 70–12 ka). Our palynological results support the notion that Lake Ohrid has been a refugium area for both temperate and montane trees during glacials. Close comparisons with other long southern European and Near Eastern pollen records will be achieved through ongoing high-resolution studies.

Environmental control on the occurrence of high-coercivity magnetic minerals and formation of iron sulfides in a 640 ka sediment sequence from Lake Ohrid (Balkans)

“…6a). Similar to the mechanism proposed above, these low-insolation phases correspond to relatively cold conditions and less dense vegetation cover, also visible in pollen abundance patterns (Sadori et al, 2015), thus increasing erosion of soil materials.…”

“…However, as already proposed by Vogel et al (2010a), vegetation cover prevented the erosion of the soil materials, and terrigenous magnetic minerals were diluted by biogenic sedimentary components. In the following glacials, vegetation cover decreased, as is indicated by arboreal pollen abundances from Lake Ohrid (Sadori et al, 2015) and soils were exposed and more susceptible to erosion. As a result, increased input of high-coercivity minerals, e.g., hematite and/or goethite, can be observed, the latter being the most widespread pedogenetic magnetic minerals (Cornell and Schwertmann, 2006;Vodyanitskii, 2010).…”

Tracing the influence of Mediterranean climate on Southeastern Europe during the past 350,000 years

“…To understand the significance of the presented data, it is important to realize that besides several available lacustrine records from the southern Balkan Peninsula (Tenaghi Philippon31, Ioannina32, Kopais33, Ohrid34 and Prespa35), other high resolution records in the interior are still missing in the Balkan region (Fig. 1).…”

Vegetation history and palaeoclimate at Lake Dojran (FYROM/Greece) during the Late Glacial and Holocene

“…In particular Pinus, Quercus robur type and Ostrya/Carpinus orientalis peaks are recorded before 12000 yr BP. Fluctuating presence of coniferous and deciduous taxa in glacial periods is recorded in several lakes of the central-eastern Mediterranean: Prespa (Panagiotopoulos et al, 2013), Ohrid (Sadori et al, 2016b), Ljubljana (Willis, 1994), Ioannina (Bottema et al, 1974;Tzedakis, 1994), Bulgarian mountain lakes (Tonkov and Marinova, 2005;Tonkov et al, 2008Tonkov et al, , 2016, Monticchio (Allen et al, 2009), Vico (Magri andSadori, 1999), Pergusa (Sadori and Narcisi, 2001), Trifoglietti (De Beaulieu et al, 2017).…”