Abstract
The Great Khingan Mountain range, Northeast China, is located on the northern limit of modern East Asian Summer Monsoon (EASM) and thus highly sensitive to the extension of the EASM from glacial to interglacial modes. Here, we present a high-resolution pollen record covering the last glacial maximum and the early Holocene from a closed crater Lake Moon to reconstruct vegetation history during the glacial-interglacial transition and thus register the evolution of the EASM during the last deglaciation. The vegetation history has gone through distinct changes from subalpine meadow in the last glacial maximum to dry steppe dominated by Artemisia from 20.3 to 17.4 ka BP, subalpine meadow dominated by Cyperaceae and Artemisia between 17.4 and 14.4 ka BP, and forest steppe dominated by Betula and Artemisia after 14.4 ka BP. The pollen-based temperature index demonstrates a gradual warming trend started at around 20.3 ka BP with interruptions of several brief events. Two cold conditions occurred around at 17.2–16.6 ka BP and 12.8–11.8 ka BP, temporally correlating to the Henrich 1 and the Younger Dryas events respectively, 1and abrupt warming events occurred around at 14.4 ka BP and 11.8 ka BP, probably relevant to the beginning of the Bølling-Allerød stages and the Holocene. The pollen-based moisture proxy shows distinct drought condition during the last glacial maximum (20.3–18.0 ka BP) and the Younger Dryas. The climate history based on pollen record of Lake Moon suggests that the regional temperature variability was coherent with the classical climate in the North Atlantic, implying the dominance of the high latitude processes on the EASM evolution from the Last Glacial Maximum (LGM) to early Holocene. The local humidity variability was influenced by the EASM limitedly before the Bølling-Allerød warming, which is mainly controlled by the summer rainfall due to the EASM front covering the Northeast China after that.
Highlights
The last deglaciation is of great interest, because the climate in the Northern Hemisphere has gone through several distinct changes such as the Last Glacial Maximum (LGM), Heinrich stadial 1 (H 1), the Bølling
The vegetation changes and reconstructed temperature and humidity index from the Lake Moon show distinct changes such as H1, B-A warming and Younger Dryas (YD) events recorded in the North Atlantic
The onset of first deglacial warming of the study area was at ~20.3 ka BP, which synchronous with the decreasing of the global ice volumes and rising of the sea level
Summary
The last deglaciation is of great interest, because the climate in the Northern Hemisphere has gone through several distinct changes such as the LGM, Heinrich stadial 1 (H 1), the Bølling-. In the Asian Monsoon region, the δ18O records from Chinese and Indian stalagmites imply a weakening of the summer IndoAsian monsoon during the YD and H 1, and stronger summer monsoon during warm period such as the B-A and early Holocene [9,10,11] They implied that topical/subtropical Asian monsoon system is responsive to Northern Hemisphere summer insolation over the last two interglacial-glacial cycles [12]. The Great Khingan Mountain range is located in the northern boundary of the EASM In biogeography, this area is a boreal-temperate forest transition zone in north-south direction as a reaction of temperature gradient, and a woodland-to-grassland transition zone in east-west direction as a response to monsoonal rainfall extension. We report a high-resolution pollen record from Lake Moon with aims to understand how the regional monsoonal climate responded to the shift in glacial/interglacial modes
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