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Vegetation and climate history during the last glacial-interglacial cycle at Lake Van, eastern Anatolia

dc.contributor.advisorLitt, Thomas
dc.contributor.authorPickarski, Nadine
dc.description.abstractThis study investigated the first continuous high-resolution pollen record from Lake Van, eastern Anatolia that encompasses the last glacial-interglacial cycle (~130 ka BP). The reconstructed paleovegetation documents a series of climatic and environmental events and yields information about vegetation succession in the Near East. Palynological analyses were extracted from the lacustrine sedimentary record obtained during the drilling campaign at the ’Ahlat Ridge’ in 2010. Being located in a semi-arid region, the regional environment at Lake Van is characterized by a continental climate. Therefore, the reconstruction of vegetation from the detailed palynological investigations reflects an alternation of an oak-steppe forest and a dwarf-shrub steppe/desert steppe vegetation. In general, cold and arid environmental conditions can be characterized by the dominance of Ephedra, Artemisia, chenopods and grasses, whereas increased temperature and moisture availability suggest more favorable environmental conditions for the expansion of a warm-temperate steppe-forest (e.g. Quercus). These climate cycles were strongly associated with changes in the oceanic and atmospheric circulation of the North Atlantic Ocean.
In eastern Anatolia the climate evolution within the last interglacial (~130- 111 ka BP) can be described as a relatively stable warm period with one pronounced short-term climate setback (C 25 cooling event; ~115 ka) towards the end of the last interglacial period. Timing and length of the interglacial conditions are comparable with southern European pollen records. Furthermore, the palynological sequence at Lake Van documents a vegetation succession with several climatic phases: (i) the Pistacia phase and the Quercus-Ulmus phase during the initial warming (130.9- 127.2 ka BP) indicating summer dryness and mild winter conditions; (ii) the Carpinus phase (127.2-124.1 ka BP) suggesting slightly colder temperatures with higher moisture availability; and (iii) the increasing Pinus phase at ~124 ka, which marks the onset of colder/drier climate conditions, that extended into the interval of global ice growth. In general, the diversity of woody taxa within the forest composition is significantly lower in the Near East compared to the eastern Mediterranean interglacial sequences.
The major difference between the last interglacial at Lake Van in comparison to the Holocene is the relatively high amount of Pinus during the Eemian, indicating a considerably higher continentality index during the climate optimum as compared to the recent interglacial.
Throughout the last glacial (~74.7-14.7 ka BP), the detailed nature of the Lake Van pollen record allows the identification of several millennial-scale vegetational and environmental changes, which can be correlated with the stadial-interstadial patterns of the Dansgaard-Oeschger (D-O) events observed in the North Greenland ice core record (NGRIP). Relatively warm and humid climate conditions during the D-O interstadials enabled the emergence of an open steppe forest at Lake Van. This study is a first attempt to establish a continuous charcoal record over the last glacial-interglacial cycles in the Near East, and to document an initial immediate response to millennial-scale climate and environmental variability. Fire regimes, confirmed to more warm/dry conditions, were considerably less frequent during glacial or cooling periods. Within the last glacial, the Marine Isotope Stage (MIS) 3 is characterized by a slightly higher fire activity than MIS 2 and 4.
New insights of paleovegetation and climate variability at Lake Van demonstrate the great potential of paleoenvironmental reconstruction. It allows the comparison with other long continental pollen records from the Near East and the eastern Mediterranean region, to contribute to the discussion of climate change and to improve the understanding of vegetational changes in the eastern Anatolia region.
dc.rightsIn Copyright
dc.subject.ddc550 Geowissenschaften
dc.titleVegetation and climate history during the last glacial-interglacial cycle at Lake Van, eastern Anatolia
dc.typeDissertation oder Habilitation
dc.publisher.nameUniversitäts- und Landesbibliothek Bonn
ulbbnediss.affiliation.nameRheinische Friedrich-Wilhelms-Universität Bonn
ulbbnediss.instituteMathematisch-Naturwissenschaftliche Fakultät : Fachgruppe Erdwissenschaften / Steinmann-Institut für Geologie, Mineralogie und Paläontologie
ulbbnediss.fakultaetMathematisch-Naturwissenschaftliche Fakultät
dc.contributor.coRefereeLanger, Martin R.

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