Abrupt climate and vegetation variability of eastern Anatolia during the last glacial

摘要

Detailed analyses of the Lake Van pollen, Ca / K ratio, and stable oxygenisotope record allow the identification of millennial-scale vegetation andenvironmental changes in eastern Anatolia throughout the last glacial(~ 111.5–11.7 ka BP). The climate of the last glacial was cold anddry, indicated by low arboreal pollen (AP) levels. The driest and coldestperiod corresponds to Marine Isotope Stage (MIS) 2(~ 28–14.5 ka BP), which was dominated by highest values ofxerophytic steppe vegetation.Our high-resolution multi-proxy record shows rapid expansions andcontractions of tree populations that reflect variability in temperature andmoisture availability. These rapid vegetation and environmental changes canbe related to the stadial-interstadial pattern of Dansgaard–Oeschger (DO)events as recorded in the Greenland ice cores. Periods of reduced moistureavailability were characterized by enhanced occurrence of xerophytic speciesand high terrigenous input from the Lake Van catchment area. Furthermore, thecomparison with the marine realm reveals that the complex atmosphere–oceaninteraction can be explained by the strength and position of the westerlies,which are responsible for the supply of humidity in eastern Anatolia.Influenced by the diverse topography of the Lake Van catchment, morepronounced DO interstadials (e.g., DO 19, 17–16, 14, 12 and 8) show thestrongest expansion of temperate species within the last glacial. However,Heinrich events (HE), characterized by highest concentrations of ice-rafteddebris (IRD) in marine sediments, cannot be separated from other DO stadialsbased on the vegetation composition in eastern Anatolia. In addition, thiswork is a first attempt to establish a continuous microscopic charcoal recordfor the last glacial in the Near East. It documents an immediate response tomillennial-scale climate and environmental variability and enables us to shedlight on the history of fire activity during the last glacial.