Holocene climate and vegetation changes inferred from pollen records of Lake Aibi, northern Xinjiang, China: A potential contribution to understanding of Holocene climate pattern in East-central Asia

This research focuses on the reconstructions of the lake hydrologic variations and the basin-wide vegetation changes over past ∼13,870 years based on pollen data of 195 samples and the lithologic variations obtained from Lake Aibi in the western part of Xinjiang area. Our results showed that lake or swamp environment did not come into existence until ∼13,870 cal. BP and swamp or wetland environment dominated the depression of the basin between ∼13,870 and ∼7430 cal. BP under ameliorated basin-wide moisture conditions. The following period between ∼7430 and ∼3620 cal. BP witnessed lake transgression in the depression and vegetation amelioration within the basin. The moisture conditions were continuously ameliorated from ∼3620 cal. BP onward, leading to further lake transgression and further basin-wide vegetation amelioration. A dry interval from ∼1400 to ∼1150 cal. BP interrupted the late Holocene wet epoch of the past ∼3600 years.Our synthesized (regionally-averaged) moisture index of Xinjiang area indicates that a gradual wetting climate dominated the mid- to late-Holocene in Xinjiang area. This wetting trend in Xinjiang area is hypothesized to have been associated with the winter warming and winter wetting trends in northern Europe. The gradual increase of winter insolation in mid- to late-Holocene might have enhanced evaporation in the North Atlantic Ocean and injected more moisture to the westerlies system, therefore bringing more precipitation to the downwind area including Xinjiang.