Vegetation history of the Eastern Mediterranean–Black Sea–Caspian-Corridor during the last 12500 years

Abstract

<p>The Eastern Mediterranean-Black Sea Caspian Corridor (EMBSeCBIO) region (33°–49°N, 20°–60°E ), is characterized by strong temperature and precipitation gradients and topographic heterogeneity, resulting in the clear patterns in biome distribution within a relatively limited geographic space. The complexity of this area is a challenge for reconstructing the dynamics of the vegetation throughout the Holocene. In this study, we apply a recently developed method to reconstruct past vegetation changes. The method uses a large dataset of modern pollen samples assigned to biomes based on potential natural vegetation cover data to characterize biomes according to the means and standard deviations of the abundances of each taxon. We use this characterization to calculate an index of dissimilarity between any given pollen sample and each biome, and thus evaluate the probability that a pollen sample belongs to a particular biome. The method also allows us to identify non-analogue vegetation types, when the scores for fossil samples are outside the range of modern scores. The vegetation reconstructions were used to produce point-to-area interpolated maps for 300 years windows. We identify periods of relative ecological stability for mapping, and also periods of rapid environmental change, by analysing high resolution (=<200 years) fossil records using a breakpoint regression approach. For quantifying ecological change, we used ordination analysis to characterize the major gradient of compositional variation in pollen records. Preliminary results indicate the presence of non-analogue vegetation at several sites during the late glacial. They document a rapid expansion of forest and semi-open forest vegetation after the late glacial period in the Black Sea region, the Balkans, the Aegean and the Carpathians, but the persistence of open vegetation types in the mountains of south-eastern Anatolia (Zagros Mountains). The reconstructions indicate the maximum expansion of temperate forest at ~6000 calibrated years BP, where it reaches the south-eastern part of Anatolia and the mountains at the south of the Aegean Peninsula. A replacement of forest vegetation by open or semi-open vegetation types occurred in the Aegean Peninsula from ~7 to 5 ky. The middle to late-Holocene transition from forest vegetation to more open vegetation types was observed across the central Aegean area, Anatolia and the Caucasus.</p>