Pollen Analysis of Holocene Loess and Vegetation Evolution in Yan'an Area

The authors present pollen assemblages and radiocarbon dating of the Holocene loess in Yan'an area.Using the pollen vegetation modeling technique,the vegetation evolution during Holocene was reconstructed.Under the background of global and regional climatic changes,Yan'an had been subjected to a whole cycle change of climate. In the middle of Holocene,the climate was at the optimum warm and humid stage, and the vegetation type was dominated by subtropical deciduous broad leaved forest, which mainly consisted of Pinus,Betula,Quercus and Rhus. During the early and later Holocene,with the dryer and cooler climate,it became coniferous broad leaved mixed forest,which mainly consisted of Pinus and Quercus.