VEGETATION AND ENVIRONMENTAL CHANGES IN THE XUANHUA BASIN OF HEBEI PROVINCE SINCE POSTGLACIAL

With the support of ¹⁴C dating,pollen analysis on Huangjiabu sections in Xuanhua Basin reflect the changes of palaeobotany and palaeoclimate. During 14000~9000aBP the vegetation in the Basin was conifer and broad-leaves forests dominated by Pinus and grassland. In some high mountains,there was coniferous forest composed of Abies and Picea,the climate was cool and wet. In 9000~2400aBP the vegetation changed into grassland dominated by Artemisia,while some deciduous broad-leaves trees such as Salix,Ulmus,Quercus and Betula also grown on some areas with suitable moisture and soil condition,the climate was warm and little dry. After 2400aBP the vegetation became desert grassland dominated by Chenopodiaceae,at the same time,the climate became cool and dry.