Glacial-interglacial vegetation changes in northeast China inferred from isotopic composition of pyrogenic carbon from Lake Xingkai sediments

摘要

Understanding the changes in monsoon intensity and ecosystem response at different timescales is crucial for the well-being of humans, yet the paleoclimatic interpretation of stable carbon isotope (delta C-13) values from northeast China records is debatable. In this study, reported delta C-13 data from 76 surface soils in northeast China are compiled, and a delta C-13 record of pyrogenic carbon (delta C-13(pyc)) from Lake Xingkai in northeast China since the last interglacial period is presented. The aim was to investigate the orbital timescale environmental implication of geological delta C-13(pyc) data for northeast China. The results showed a distinct increase in delta C-13 values of surface soils, which correlated with increasing temperature of the warmest month. Higher temperature favored the expansion of C-4 plants, while precipitation had only a weak correlation with delta C-13 values of surface soils in the region. On an orbital timescale, the delta C-13(pyc) record from Lake Xingkai generally reflected paleovegetation change, suggesting that the abundance of C-4 plants was relatively high during the warm periods, changing to almost purely C-3 plants during the cold periods. Both modern and geological analysis suggest that the climatic factor determining the delta C-13 in northeast China was temperature of the warmest month. This is similar to the situation for mid-latitudes such as the Chinese Loess Plateau, in contrast to low latitudes such as southern China. (C) 2018 Elsevier Ltd. All rights reserved.