Moisture conditions during the Younger Dryas and 4.2 ka event as revealed from a subalpine peat record in the Luoxiao Mountains, southern China
2022
Shuchun, Yao | Chunhai, Li | Yangsheng, Chen | Yongfei, Li | Lingyu, Tang | Ji, Shen | Bin, Xue
A 150 cm long peat core was collected from a subalpine peatland (above sea level 1790 m) in Luoxiao Mountains，Hunan Province, China. Based on the analysis of AMS ¹⁴C dating, loss on ignition, total carbon, total nitrogen, grain size, humification, and pollen data, the environment change was reconstructed focusing on the intervals of the Younger Dryas (YD) event, the 4.2 ka event, and modern time. The pollen record indicates that deciduous broad-leaved trees occupied most parts of the study region and subtropical trees also grew at the lower elevation areas during the deglaciation. The percentages of Quercus (D) reached the highest during the YD, suggesting lowered temperatures than that of the pre-YD. Comparing with modern pollen assemblages, the relative abundance of Tsuga was lower during the 4.2 ka event, suggesting that the temperature were lower than that of the present. Regional comparisons of multiple proxy data in eastern China revealed that the climate was wet in northern China during the YD, which was probably related to the weakening evaporation effect and the strengthening Okhotsk High under low-temperature conditions. During the YD, the climate in the area dominated by the Indian monsoon was relatively dry in the southern part of eastern China. Meanwhile, in the East Asian monsoon-affected region, the climate was relatively wet during the YD in the southern part of eastern China, which was related to the weakening of the East Asian monsoon, El Niño conditions, and the West Pacific Subtropical High.
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