Paleovegetation and Paleoclimate Evolution of Past 27.7 cal ka BP Recorded by Pollen and Charcoal of Lake Xingkai, Northeastern China

Abstract

Lake Xingkai, a transboundary lake by China and Russia, is the largest freshwater lake in Northeast Asia. An 269 cm long continuous sediment core from Lake Xingkai, has been analyzed firstly in China for pollen and charcoal, in order to study the paleovegetation and paleoclimate evolution in the area. Vegetation and climate change history of Lake Xingkai have been reconstructed since the 27.7 cal ka BP. During 27.7 ∼ 25.5 cal ka BP, the study region was occupied by forest steppe dominated by Poaceae, Artemisia, Chenopodiaceae and Picea that reflected a cold and slightly dry climate. Later, between 25.5 ∼ 23.7 cal ka BP, the study region was occupied by coniferous and broad-leaved mixed forest steppe which reflected a relatively cold-wet climate. During 23.7 ∼ 19.9 cal ka BP, which corresponded to LGM (Last Glacial Maximum), the study region developed broad-leaved forest steppe indicated cold and dry climate condition. From 19.9 to 14.5 cal ka BP, there was broad-leaved forest steppe with Betula and Artemisia as the main component when Pediastrum and Ferns increased greatly, which suggested a cold-wet climatic trend. During 14.5 ∼ 10.8 cal ka BP, the study region was occupied by sparse forest grassland with Picea, Betula, Artemisia and Poaceae as the main components. This stage that corresponds to Bolling/Older Dryas/Allerod/Younger Dryas, was a climatic transition period from warm-wet to cold-dry. From 10.8 to 1.0 cal ka BP, the study region was occupied by broad-leaved forest steppe, which indicated climate changed from temperate and moist to warm and slightly dry in Holocene. After 1.0 cal ka BP, coniferous forest developed with Pinus as the main component, indicated climate changed to cool and dry again and human slash activity influence.