Study On Human Activities And Living Environment Background In Changbai Mountain During The Bohai Kingdom

As an important geographical unit in the Northeast and even in China,the special geographical location and natural environment of the Changbai Mountain have always attracted much attention to the environmental evolution on a long time scale,and the rich natural resources have also made it a fertile ground and cradle for nurturing the Northeast regional culture.The Bohai Kingdom was an ethnic minority regime established in the Changbai Mountains during the Sui and Tang dynasties,mainly by the Mohe people of the Sushin tribe,and during its development for more than 200 years,it fostered an unprecedentedly developed national economy and a splendid Bohai culture,and promoted the further development of the Northeast frontier.This paper takes the relationship between human activities and environmental background in Changbai Mountain during the Bohai Kingdom as the fundamental goal of the study.Firstly,microfossil analysis of soil samples from six typical archaeological sites of the Bohai Kingdom was carried out,and combined with the results of phytolith and pollen analysis in the site area and some relevant data,the types of crops planted by the Bohai ancestors and the planting structure were recognized,and the impact of the Bohai ancestors’ activities on the surrounding environment of the site area was explored.Then,we selected a natural sedimentary peat profile,reconstructed the evolution of regional paleovegetation based on pollen,and analyzed the interference of human activities on regional natural vegetation during the Bohai Kingdom.In addition,the paleoclimate was reconstructed by phytolith to clarify which phase of the climate fluctuation cycle the Bohai Kingdom was in during its existence,and to explore the background of moisture and thermal conditions for the flourishing of agriculture in the Bohai Kingdom.The main conclusions of this paper are as follows:(1)Compared with the reign of previous regimes,the Bohai Kingdom made progress in farming patterns,crop types,and water irrigation;the crop types cultivated in and around the capital cities included Setaria italica,Panicum miliaceum,Hordeum vulgare,Triticum aestivum and rice;the rice was identified as O.sativa subsp.japonica by the morphological parameter of phytoliths.The agriculture near the capital cities was occupied by both dryland farming and rice-based farming.Among them,dryland farming still dominates,and rice as a newly introduced crop became a specialty of the Bohai kingdom,but was not commonly cultivated.(2)The palaeoenvironmental evolution of the Changbai Mountains during the historical period has experienced four stages: 2850-1530 cal yr BP,the environmental landscape is relatively primitive with few human activities,the regional vegetation is mixed coniferous forests mainly composed by Pinus,Quercus,Juglans,Ulmus,the climate is relatively warm and humid.1530-1080 cal yr BP,the forest slightly shrank in this period,and at the end period,the Pinus decreased and the herbaceous plants increased suddenly,which may indicate that human activities have begun to affect the regional vegetation,the temperature is more suitable and the precipitation fluctuates.At 1080-140 cal yr BP,the forest cover is relatively low,but the species diversity is elevated,showing a typical mixed coniferous forest vegetation dominated by Pinus and mixed with Quercus,Betula,Ulmus and Juglans.Temperature and precipitation fluctuate more drastically,and the climate has a tendency to be cold and dry.After140 cal yr BP,the regional environment was obviously disturbed by various factors,the abundance of nitrogen-loving plants and Poaceae closely related to human activities increased significantly,and the temperature also notably increased.(3)The disturbance of human activities on the vegetation of Changbai Mountain during the Bohai kingdom is more obvious than other stages of the historical period,which is reflected by the massive reduction of Pinus and the increase of herbaceous plants.The intensity of human activities near the site is much stronger than that of the natural area,with the reduction of vegetation diversity,the decrease of pollen concentration,and the dominance of companion herbaceous plants.Combined with historical and archaeological data,it is believed that with the development of various construction and the growth of military and civilian needs during the Bohai kingdom,the intensity of deforestation by the ancestors reached an unprecedented levels,and the response of vegetation to human activities was especially obvious in the area around the settlement.(4)The Bohai Kingdom is in the warm phase of 200-300 years temperature cycle,in the relatively humid stage of ～500 years precipitation cycle,and the suitable temperature conditions are favorable for agricultural cultivation,relatively low precipitation did not limit agricultural development.The parent climatic suitability become one of the important factors to promote the development of agriculture in the Bohai.