Response Of Human Activities To Environmental Changes In The Ordos Plateau During The Holocene

Holocene is the most closely related period in the history of the earth.In recent years,with the emergence of global environmental problems,the relationship between Holocene environmental changes and human activities has become a research hotspot of different disciplines.The research on the response of human activities to environmental changes in the agro pastoral ecotone can provide a scientific basis for understanding the evolution of human land relationship in different spatial-temporal scales in this area.In this paper,the methods of geography,environmental archaeology,historical literature and GIS analysis has been used to study the response of Holocene human activities to environmental change in the Ordos Plateau.This study not only has scientific significance for the basic theoretical research of environmental change and human land relationship in the agro pastoral ecotone,but also provides scientific basis for ecological protection,rational development and utilization of resources,prediction and control of desertification in the Ordos Plateau.Human archaeological sites are excellent spatiotemporal indicators for the study of historical human activities and environmental change.Based on the statistics of the characteristics of prehistoric and historical human archaeological sites since Neolithic Age in Ordos,this paper analyzed the influencing factors of the spatial distribution of the sites,and further discussed the reasons for the temporal and spatial changes of the sites.Studies have shown that the human archaeological sites in Ordos Plateau were mainly small and medium-sized and sites of farming regime,the number of nomadic regime sites was small,and they were mainly distributed in the north of the Ming Great Wall.The number and occurrence frequency of human archaeological sites showed a phased upward-decreasing fluctuation process.Elevation,slope,aspect,water source and non-desert area have a strong influence on archaeological site environmental selection.The spatiotemporal distribution pattern of human archaeological sites in the Ordos Plateau was the result of the combined action of natural and human factors.The natural conditions of the overlapping human archaeological sites were superior,but the number was small.When the climate was warm and humid,the number of the human archaeological sites increased significantly,and the spatial distribution spread across the Ordos Plateau;when the climate was cold and dry,the number of sites was relatively small and scattered distribution.In addition,the frequency of human archaeological sites was significantly affected by the local people's livelihood pattern.On the basis of the above research,this paper discussed the response of human activities to environmental change from two aspects of water environment change and desertification,and then summarizes the overall evolution law of human land relationship in Ordos Plateau.Based on the field investigation of the ancient well,spring and ancient city of Sanchahe in the upper reaches of Wuding River,as well as¹⁴C dating,grain size,spatial analysis of archaeological sites,and analyses of historical seismicity,indicated that neotectonics may have contributed to crustal uplift and accelerated fluvial incision of the Wuding River.This rapid incision caused a decline in groundwater levels,which is an important reason for the desertification around the upper reaches of Wuding River.In addition,the shrinkage of lakes in historical periods usually led to the migration of human activities,and then had an impact on the regional political and economic center.Based on the statistics of paleosol,aeolian sand age accumulation frequency and sand dune bottom ages,it is found that there are obvious stages and periodicity of desertification in Ordos Plateau.Due to the influence of climate change,the Ordos Plateau has experienced three obvious desertification processes since 2000.By analyzed the response of human activities to environmental changes in the Ordos Plateau since the Holocene,it is found that there is an obvious‘sponge effect'in the evolution of human land relationship in the Ordos Plateau.When the environment was suitable,it‘absorbs'a large number of people,and when the environment began to deteriorate,these people were‘squeezed'out to other areas.This kind of population migration results in the imbalance of population resources in relatively suitable resource areas in a short time,and then leads to the war between farming and nomadic.