The Environmental Background And Human Activities For Zhengding Ancient City Site In Tang Dynasty

Nowadays,the contradiction between man and land has become increasingly prominent,and the relationship between man and land has become a major issue of common concern in human society.Therefore,in order to understand the current man-land relationship,we must study human activities and environmental changes,and understand the evolution history of the relationship between human activities and environmental changes.Tang Dynasty is an important period of cultural prosperity in Chinese history,and it is also a period when Zhengding ancient city site began to form and gradually prosper.In recent years,a lot of cultural relics have been found in the Zhengding Kaiyuan Temple South Square archaeological site.There are seven superimposed cultural layers of Tang Dynasty,Five Dynasties,Song Dynasty,Jin Dynasty,Yuan Dynasty,Ming Dynasty and Qing Dynasty in the site.The archaeological evidence of each period has been well preserved.Especially the layer of Tang Dynasty was thick and covered a wide area.It is an ideal location for the study of the environmental changes and human activities in Zhengding area in the Tang Dynasty.Based on AMS-¹⁴C dating and archeological dating,this paper reveals the environmental background of Zhengding Ancient City Site in Tang Dynasty and its relationship with human activities by using pollen analysis,combined with charcoal,grain size and phytolith.The results show that the surrounding areas of Kaiyuan Temple in Zhengdinghas a long history of development due to the effect of human activities earlier,so the vegetation of it has been damaged,which makes local vegetation given priority to with herbs on the whole,an average of 83.6%.However,there are great changes in different historical stages:（1）The results of grain size analysis in the study area show that:In the early Tang Dynasty（before 760 A.D.）,the average median grain size reaches the lowest value（19.37μm）,the content of sand is the lowest（12.85%）and the clay content is the highest（15.4%）.On the whole,the hydrodynamic condition is relatively weak,and the sedimentary environment is relatively stable,which created condition for the development of Zhengding ancient city,while in the late Tang Dynasty（After760A.D.）,the sand content increased significantly（15.31%）,and the grain size became coarser（25.25μm）,which was not only the highest on average in the study section,but also the peak（37.1μm）appeared in this period.The hydrodynamic conditions were strong,and there might be large-scale floods,which affected urban development.（2）The results of pollen and charcoal analysis show that:In the early Tang Dynasty（680-760 A.D.）,the local population increased significantly,and the intensity of human activities increased significantly,which led to a significant decline in forest coverage in the study area.The pollen content of trees represented by Pinus decreased significantly compared with that before the Tang Dynasty,from 22.7%to 9%,while that of herbs represented by companion plants and crops decreased significantly.The content of Artemisia increased from 4.4%to 20%,Poacea（<30μm）increased from14.1%to 17.4%,and the content of crops pollen（Poacea≥30μm）increased from8.6%to 13.4%,which was the highest in the study period.Meanwhile,the content of crops pollen decreased from 17.1%to 5.6%,and the total concentration of charcoal decreased sharply from 201×10³grains/g to 4×10³ grains/g;the occurrence of economic center moving southward makes the trend of human activities and environmental changes in the South and north of China have obvious regional differences.（3）Phytolith analysis showed that the relative content of Millet in crops was the highest,followed by Panicum and Triticum,which indicates that grain crops in Zhengding area during Tang Dynasty were mainly planted with Millet,supplemented with Panicum and Triticum.