Human Activities And Environmental Change InThe Hinderland Of Qinghai-Tibet Plateau

This article selects CXGS section in the hinterland of Tibet plateau as the research object,the relationship between environmental evolution and human activity in CXGS area was researched by the combination of field sampling,investigation,laboratory experiment(chromacity,particle size,magnetic susceptibility,kish carbon and sporopollen)and GIS technique.This study showed the human activities mainly focus on two time periods,Holocene Megathermal and Late Holocene respectively,the time of human's arriving in Zhiduo county and the upper reaches of the Yangtze River dated back to 8.6-7.8 cal ka BP.The pollen data showed that there was better vegetation coverage in CXGS area at that time,the vegetation type was grassland,wich was dominated by compositae and artemisia,meanwhile,accompany with picea and pinus.The higher redness,magnetic susceptibility and small median size revealed that the climatic environment in CXGS area was warm and wet.The total concentration of charcoal shows that it was high during 8.6-7.8 cal ka BP,at that time the number of unearthed microlith was maximum,which revealed that human activities was frequent and strong;At about 2.3 cal ka BP,the charcoal concentration showed increasing trend,which may be resulted from frequent and strong human activity.At about 8.6 cal ka BP,prehistoric human activities occurred in CXGS area,the optimum climatic environment and natural environment may drive prehistoric human to expand towards the highland of Tibet Plateau.The living and producing style was seasonal gathering and hunting;In Late Holocene,the living and producing style in CXGS area transformed from gathering and hunting to nomadic economy,which was dominant by animal husbandry.Since the last deglaciation,the microlithic human activities on the Tibetan plateau had temporal and spatial variations.During the last deglaciation,the improvement of climate and natural environment drove the prehistoric human to move towards Qinghai Lake basin and Gonghe basin at 3000 metres above sea level;The rising temperature and increasing precipitation drove the prehistoric human to expand towards the area at 4000 metres above sea level;The optimal climateenvironment and superior natural environment during the Holocene Megathermal driven microlithic hunters to expand towards the hinterland of Tibet Plateau above4000 metres above sea level.The research on environmental evolution and human activity can lay the foundation for understanding how human occupy Tibet Plateau step by step,and provide some references for how human adapt environmental and climatic changes.