Phytolith Record Of Climatic Change Since The Last Glacial Maximum From Peat Core In Daiyun Mountain,Fujian Province

Fujian is located in the front zone of East Asian Summer Monsoon and the tail zone of Winter Monsoon,which is significantly affected by subtropical high,tropical cyclone,ENSO and other mid-low latitude air-sea processes.Its climatic characteristics are significantly different from those of Yangtze River basin,Huang-Huai River basin and North China.As a good carrier of past climate change,peat is of great significance for the reconstruction of palaeoclimate and palaeoenvironment.A 227 cm and 90 cm depth core were excavated from Daiyun Mountain.Based on detailed phytolith analysis,the climate change process and event characteristics in Fujian since the last glacial maximum were reconstructed.The main results show as follow:(1)During 20.6 to16 cal kyr BP,dominate phytoliths is Bulliform.The dry types persist in relatively low abundance,such as Bilobate,Short-saddle,Wavy-trapezoid and Rondel,indicating a cold and wet climate at this time.A relatively dry climate had arise in the 16～6 cal kyr BP.The abundance of Bilobate,Short-saddle,Wavy-trapezoid and Rondel increased but the Bulliform percentages decreased rapidly,reflect warm and dry conditions during 6～0cal kyr BP.(2)During the LGM period,there are significant differences in dry-wet condition.The northern region is cold-dry and warm-humid,the Southern region is cold-humid and warm-dry.This may be related to the proximity of the study area to the sea,even in the cold and dry ice age,the moist air mass can still penetrate deep into the study area.(3)In the LHC core,phytolith analysis showed that the warm and humid climate from 1200～710cal yr BP corresponds to the MWP;the cold-dry climate from710～110cal yr BP corresponds to the LIA,and the warm-drier climate from110 cal yr BP is similar to the CWP.During MWP,with warm and humid climate condition and included a progressively warm and humid sub-stage from 1200～910cal yr BP and a warm-dry sub-stage from 910～710cal yr BP.(4)The precipitation changes during the MWP may have explanations associated with EASM and ENSO variability.The humid early-MWP probably caused by the weaker EASM and more El Ni?o conditions.However,during the late-MWP,intensified EASM and more La Ni?a-type conditions,leading to less Mei-yu precipitation in the Southern of China,which may be the primary cause of drier in the late-MWP than the earlier stage.