EARLY TO MIDDLE HOLOCENE ENVIRONMENTAL CHANGES AND AGRICULTURAL ACTIVITIES IN BASHANG STEPPE,NORTHERN CHINA
The change of climate and environment from the Late Pleistocene to the Holocene had a profound impact on human society,which gradually transited from the mobile hunting-gathering to sedentism and agricultural way.It is well known that millet farming originated in the Northern China.Only a few sites with microfossil evidence of millet have been found in the Early Holocene,but millet seeds are commonly revealed in plant remains during the early Middle Holocene(8500～7000 cal.a B.P.)in the Northern China.Aiming to understand the relationship between the development of millet agriculture and environmental changes in the Northern China from Early to Middle Holocene,the total organic carbon(TOC),grain size and magnetic susceptibility were analyzed from a 480 cm deep natural sediment section ST2015(41.31°N,114.23°E)in the Sitai site area,Bashang steppe in Hebei Province.Ninety-six soil samples were collected at 5 cm intervals though the section ST2015.Eight full samples were selected for AMS 14C dating to reconstruct the chronological framework for the section.The dating of modern soil layer(0～20 cm)was 360±30 a B.P.Therefore,the age of 360 years was used as the carbon reservoir in the section.All the dating results were calibrated using OxCal v.4.0 program after subtracting 360 years.The age-depth model was built using the Bacon program.Ninety-six samples were used for the analysis of TOC,grain size and magnetic susceptibility to understand the environmental changes from the section.The AMS 14C dating and grain size records revealed that the ST2015 section is an eolian sediment with age range from 15000 cal.a B.P.to present.Lower TOC and magnetic susceptibility with coarse grain size indicated the climate was relatively arid before 11500 cal.a B.P.TOC and magnetic susceptibility began to increase rapidly in the Early Holocene,and reached their highest values in the early Middle Holocene(8500～7000 cal.a B.P.).It revealed that a higher biomass and wettest climate in the study area during early Middle Holocene.The animal and plant remains revealed a hunting-gathering economy during early Holocene,while a mixed hunting-gathering and agricultural economy occurred during early Middle Holocene in the Bashang steppe.Our study suggested that the warm and humid climate promoted the development of forest-grassland vegetation,the expansion of other resource-based plants,and the improvement of land productivity in the early Middle Holocene.Abundant resource conditions facilitated sedentism and the development of low-level millet farming in the early mid-Holocene in the Northern China.
万方数据
维普
