Response of carbon accumulation dynamics in the peatlands of Changbai Mountain to climate change over the past 2000 years

Peatlands occupy only 3% of the land area, but store nearly 30% of soil organic carbon (Yu et al., 2010; 2014). Thus, peatlands are one of the most important carbon reservoirs on land. Whether peatlands will become a carbon source or sink as the climate warms varies in different study regions (Gallego-Sala et al., 2018). In order to answer this question, it is necessary to select the past typical warm period as the "historical similarity" to explore the relationship between the carbon accumulation in peatland and climate change during this period. The past 2000 years includes the Roman Period, the Medieval Warm Period, the Little Ice Age and the Global Warming Period, which are the focus of the International Program on Past Global Changes (PAGES). A study of the relationship between peatlands and climate change in the last millennium on a global scale shows that the carbon sink of peatlands in northern regions is increased after rising temperature, while the opposite is true for peatlands in low latitudes (Galleau-Sala et al., 2018). Where is the latitude limit?The Changbai Mountain is located between the northern peatlands and low-latitude peatlands. The peatlands distribute widely in the Changbai Mountain and are less affected by human activities. Thus, the Changbai Mountain is one of the ideal regions to explore the response of peatland development to climate change (Hong et al., 2000; Zhou et al., 2010; Zheng et al., 2018). In this paper, four peatlands (Jinchuan, Baijianghe, Lushuihe and Laolike) were selected from west to east around the main peak of Changbai Mountain, and six peat profiles were drilled in total. With the support of AMS14C and 210Pb/137Cs techniques, the dynamics of carbon accumulation in peatlands and its response to climate in this area in the past 2000 years were discussed. The results show that the carbon accumulation rate of the four peatlands with similar latitudes was higher during the warm and wet period of the Roman Period and the Medieval Warm Period, and lower during the Little Ice Age, which is consistent with the northern peatlands. But the carbon accumulation rate showed a downward trend during the global warming period, which is similar to the low-latitude peatlands. This suggests that the carbon accumulation rate of peatland in Changbai Mountain may increase with the increase of temperature within a certain range. But the rate of carbon accumulation will decrease when the temperature rises beyond the limit. It also suggests that if the climate continues to warm in the future, the carbon sink function of peatlands in the region will be weakened. Exploring the response of carbon accumulation dynamics to climate change in peatland of Changbai Mountain is helpful to clarify the latitude limit of carbon accumulation change in peatland and predict the trend of carbon accumulation change in peatland after climate warming.