Human Wood Utilization Strategy In The Northeast Of Tibetan Plateau During The Neolithic And Bronze Age

Human-environment interaction,including its evolutionary process,objective law and mechanism,is a widely concerned frontier scientific issue for scholars from multidisciplinary such as geography,anthropology and archaeology.It is important to reveal the spatio-temporal evolutionary process and law of man-land relationship by studying human-environment interaction in the past,which is also referential in facing the challenge of climate-change impact on the sustainable development of human society.The northeast part of the Tibetan Plateau,with abundant archaeological remains,significant spacial difference of the natural environment and sensitive response to climate change,is a hot spot in studying human-environment interactions in the past.In recent years,study on human-environment interaction during prehistoric period in this area has acquired important progress.Basing on the identification and analysis of crop and animal remains unearthed from Neolithic and Bronze Age sites,study on the process and driving force for permanent human occupation of the Tibetan Plateau has achieved breakthrough,in the vision of prehistoric human utilization strategy of animal and plant resources.However,in lacking of systematic identification and analysis on wood charcoal remains in Northeast Tibetan Plateau(NETP),the utilization strategy of ancient human on wood resources still remain unclear,which demand further research.This study provides robust material and evidence in understanding the environmental background in NETP for prehistoric human living,different survival strategy taken by ancient human to adapt to the diverse environment in different altitude and the impact of prehistoric human activity on local vegetation during different periods.Furthermore,this study is important and valuable for understanding the evolutionary process and objective law of prehistoric human-environment interaction on the Tibetan Plateau.In this study,systematic species identification and statistical analysis wereundertaken on wood charcoal remains unearthed from Neolithic and Bronze Age archaeological sites.A total amount of 162 wood charcoal samples were collected from 25 archaeological sites(including 24 sites surveyed and 1 site excavated)in NETP while 8084 pieces of wood charcoal were identified.Combining with published archaeobotanical and zooarchaeological evidences,we synthetically analyzed human utilization strategy on wood resources in different period and region during Neolithic and Bronze Age in NETP.Based on this foundation,we compared high-resolution paleoclimatic records and archaeological evidences in NETP and adjacent areas to discuss the spatio-temporal pattern of the shift in wood utilization strategy of people in NETP during Neolithic and Bronze Age.Beyond that,the relationships of the regional environment,climate change,cross-continent cultural exchange,subsistence strategy and the shift of wood utilization strategy were also discussed.On the basis of this study,some main conclusions and new cognitions are listed below:(1)In NETP,human utilization of wood resources was restricted by the surrounding forest resources during Neolithic and Bronze Age.The selection of wood resources was likely to be subjective,with coniferous as primary choice while broad-leaved species and shrubs as secondary.(2)In NETP,conifers were the main wood resources collected and utilized by people of Majiayao Culture and Zongri Culture while difference existed in species.Among them,people of Zongri Culture mainly collected the Picea,while people of Majiayao Culture mainly utilized the Pinus.For fruit utilization,people of Zongri Culture only utilized Hippophae,while the Majiayao crowds utilized 5 taxa.People of Qijia Culture mainly utilized conifers(such as Pinus)as their wood resource with 6taxa of fruit trees.Among all wood resources utilized by people of Xindian Culture,proportions of coniferous and broad-leaved trees were quite close.People of Cayue Culture employed a wood utilization strategy in which broad-leaved trees were primary and coniferous were secondary with 7 kinds of fruit trees were utilized.As for people of Nuomuhong Culture,shrubs were at dominant position in wood utilization and no fruit trees were utilized.(3)In NETP,a significant spacial difference existed in wood utilization strategy of ancient human during Neolithic and Bronze Age.With the rising altitude,the amount of species utilized as wood resources decreased.During 4600-4000 BP,ancient human living in different altitudes uniformly utilized coniferous trees as mainwood resource.However,for those who lived in areas around 2800 masl,Picea were at most among all taxa of woods utilized.Meanwhile,for those who lived under 2500 masl,Pinus were at most.Spanning the time from 3600 to 2300 BP,people who lived in areas at 1700-2100 masl,2400-2800 masl and 2800-3100 masl utilized wood resources in different ways,by mainly utilizing both broad-leaved and coniferous trees,broad-leaved trees,and shrubs,respectively.(4)In NETP,wood utilization strategy of ancient human has shown different characteristics in different periods.In areas below 2500 masl,coniferous was basically at primary position during 5200-3600 BP.However,broad-leaved tree gradually increased its proportion in wood utilization during this period and became dominant wood resource in 3600-2300 BP.For areas above 2500 masl,samples from Zongri site revealed coniferous as primary wood resource and a rise of its proportion during 4600-4000 BP.When it came to 3600-2300 BP,broad-leaved trees and shrubs became dominant wood resources in Kayue Culture and Nuomuhong Culture,respectively.(5)In NETP,wood utilization strategy of ancient human was influenced by multi-factor during Neolithic and Bronze Age.The spacial variation of natural vegetation was an important influencing factor leading to different wood utilization strategies during the entire study period.Climate change during 4600-4000 BP might have some effect on wood utilization strategy of Zongri crowds by causing a shift of vegetation in the local region.Cross-continent cultural exchange facilitated expansion and intensification of human occupation in NETP during 3600-2300 BP.Especial for Kayue Culture,the disturbance of human activities on the local woody vegetation significantly enhanced.The diversity of human subsistence strategies is another influencing factor leading to a spatial difference of wood utilization strategy during5200-2300 BP.For instance,agricultural population utilized more fruit trees than hunter-gatherers and herders.It is the first time to introduce systematic identification and analysis of wood charcoal remains into NETP which provides significant data support in comprehensively understanding the plant utilization strategy of ancient human to adapt to the changing living environment during the late prehistoric times in NETP.Moreover,this study contributes new perspective in discussing the evolutionary pattern of human-environment interaction in key region under the background of the emerging and gradually strengthening prehistoric trans-Eurasia culture exchange.