Evidence of Lateglacial and Holocene climatic change and human impact in eastern Anatolia: high-resolution pollen,charcoal,isotopic and geochemical records from the laminated sediments of Lake Van,Turkey

Abstract

Annually laminated sediments from Lake Van, spanning about 13000 varve years, were sampled for stable-isotopic, geochemical, pollen and charcoal analyses in order to find evidence of past regional climatic changes and human impact in the semi-arid region of eastern Anatolia, Turkey. The Lateglacial period was cold and dry, with steppe vegetation and saline lake water. During the Younger Dryas the lake level dropped dramatically, and the vegetation tumed to a semi-desert. Geochemical and isotopic records indicate a strong increase in moisture at the onset of the Holocene, and Arteinisia-chenopod steppes were partly replaced by grass steppe and pistachio scrub. A delay of about 3000 years in the expansion of deciduous oak woodlands and high steppe-fire frequencies suggest dry spring and summer weather during the early Holocene. At 8200 yr BP, a shift in the regional climate regime facilitated the transport of more moisture into the interior areas of the Taurus mountains and caused a change in the seasonal distribution of precipitation. The steppe-forests dominated by Quercus advanced and reached their maximum extention at about 6200 yr BP. All the proxy data indicate optimum climatic conditions, low water salinity and high lake level between 6200 and 4000 yr BP. After 4000 yr BP, aridity increased again and the modern climatic situation was established. Human impact in the catchment of Lake Van started at 3800 yr BP and was intensified during the last 600 years.