Climate Variation Record From Peat In The Changbai Mountains Since The Middle-late Holocene

The climate variations during Holocene,which was closely related to human civilization,influenced many aspects of human being.The paleoclimate reconstruction in Holocene is helpful to obtain the rule of climate change and predicting the future climate.The Changbai mountains area which located in Northeast China is sensitive to global change.Due to unique climatic and hydrological conditions,peatlands were widely developed in this area.The peat in the Changbai mountains area was characterized by continuous deposition and good preservation.It is an ideal carrier for the study of palaeoclimate change.137 samples from Dongfanghong and 157 samples from Jinbei peat profile were obtained in this area to analyses plant macrofossil,loss on ignition and humification of samples,respectively.Combined with AMS¹⁴C dating technique,we rebuild the history of climate variation history since the 6800yr BP.Moreover,the driving mechanism of climate change was also discussed.The main conclusions of this article are as follows:?1?Sphagnum mainly appears on the surface,and the wood is mainly distributed at the bottom of the profile.DCA analysis of plant macrofossil in Jinbei and Dongfanghong peat profile showed that DCA1 axis could be used as the indicator of the surface humidity of the peatland.According to DCA1 axis score,humification and loss on ignition,we rebuilt the surface humidity variation in Jinbei and Dongfanghong peatlands.The surface humidity process of Dongfanghong peat since 6800yr BP is as follows:wet stage-dry-wet alternating stage-wet stage-dry stage.The process of surface humidity in Jinbei peat since the 6000yr BP was:wet stage-alternative dry-wet stage-wet to dry stage.?2?The climate variation in the Changbai mountains area has experienced the following four stages during the last 6800yr BP:relatively wet period from 6800yr BP to 3600yr BP,wet period from 3600 to1400yr BP,fluctuation between dry and wet period from 1400 to400yr BP,and transition from wet to dry period since 400yr BP.?3?Dongfanghong and Jinbei profiles recorded some of the global climate events,such as“5.9 Ka BP”,“4.2 Ka BP”,“2.8 Ka BP”and“1.4 Ka BP”incident.The Dongfanghong peatland recorded a large volcanic eruption that occurred between 1014-1019 AD.Therefore,the records of the Medieval Warm Period was missing,without record of the Little Ice Age.The Jinbei peat profile does not reflect the Medieval Warm Period and the Little Ice Age.?4?The climate change in the Changbai mountains area in the Holocene is not only affected by the east Asian summer monsoon,but also related to the changes of solar activity.In addition,the north Atlantic ice raft event could have also had an impact on climate change in the region.