Younger Dryas To Mid-Holocene Environmental History Of The Lowlands Of NW Transylvania, Romania

Pollen, micro-charcoal and total carbon analyses on sediments from the Turbuta profile located in the Transylvanian Basin (NW Romania) reveal information on previously unknown Younger Dryas to mid-Holocene environmental changes. The chronostratigraphy relies on AMS 14C measurements on organic matter and U/Th TIMS datings of snail shells. Results indicate the presence of Pinus and Betula open woodlands with small populations of Picea, Ulmus, Alnus and Salix before 12,000 cal yr BP, correlates well with the environmental developments expected for Younger Dryas stadial. A fairly abrupt replacement of Pinus and Betula by Ulmus dominated woodlands at ca. 11,900 cal. yr BP, likely represents competition effects of vegetation driven by climate warming at the onset of the Holocene. By 11,000 cal yr BP, the woodlands were increasingly diverse and dense with the expansion of Quercus, Fraxinus and Tilia, the establishment of Corylus, and the decline of upland herbaceous and shrubs taxa. The marked expansion of Quercus accompanied by Tilia between 10,500 and 8,000 cal yr BP could be the result of low effective moisture associated with both low elevation of the site and with regional change towards a drier climate. At 10,000 cal. yr BP Corylus spread across the region, and by 8,000 cal yr BP it replaced Quercus as a dominant forest constituent, with only little representation of Picea abies. Carpinus became established around 5,500 cal yr BP, but it was only a minor constituent in local woodlands until ca. 5,000 cal yr BP. Results from this study also indicate that the woodlands in the lowlands of Turbuta were never closed.