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.

Climate versus human-driven fire regimes in Mediterranean landscapes: the Holocene record of Lago dell’Accesa (Tuscany, Italy)

“…This reconstruction is supported by stalagmite data from Corchia cave (northern Italy) that suggest increased of precipitation in the western Mediterranean during the deposition of Sapropel 1 (Zanchetta et al, 2007). Charcoal data available from Lago di Pergusa in upland Sicily (Sadori and Giardini, 2006) and from Lake Van in Turkey (Wick et al, 2003) also attest to high CHAR until 8400/8200 cal. yr BP.…”

“…Such climatic conditions could explain the occurrence of laminated sediments at Lago dell'Accesa and could have advantaged fires, since dry summer conditions favour fire ignition and expansion. In agreement, charcoal series from around the Mediterranean basin in Sicily (Lago di Pergusa, Sadori and Giardini, 2006), Spain (Lake Siles; , and Turkey (Lake Van;Wick et al, 2003) also show high charcoal values during the early Holocene that were attributed to frequent fires. Similar results were obtained on the west coast of North America (Millspaugh et al, 2000;Gavin et al, 2003a;Whitlock et al, 2007;Anderson et al, 2008).…”

Interpreting lake isotope records of Holocene environmental change in the Eastern Mediterranean

“…Wick et al (2003) compared these isotope and geochemical data against the pollen record from Van. As at Eski Acıgöl, the pollen record showed a rapid increase in grasses at the beginning of the Holocene followed by a slower increase in trees.…”

River inflow and salinity changes in the Caspian Sea during the last 5500 years

“…In the Holocene, the Aral Sea and Lake Van (eastern Turkey) show a humid climate or high lake levels until c. 4000 cal. yr ago (Boroffka et al, 2006;Wick et al, 2003) that could correspond to the first period of river inflow and lower salinities of core CP14.…”