| 引用本文: | 赵亚娟，候光良，鄂崇毅，杨 龙，王青波.2016.青藏高原下大武地区炭屑浓度所反映的环境演变与人类活动[J].地球环境学报,(1):19-26 |
| ZHAO Yajuan, HOU Guangliang, E Chongyi, YANG long, WANG Qingbo.2016.Charcoal concentration reflect of environment change and human activities in Xiadawu Relic, Qinghai-Tibet Plateau[J].Journal of Earth Environment,(1):19-26 |
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| 青藏高原下大武地区炭屑浓度所反映的环境演变与人类活动 |
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赵亚娟，候光良，鄂崇毅，杨 龙，王青波1,2
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1.青海师范大学 青藏高原环境与资源教育部重点实验室，西宁 810008;2.青海师范大学 青海省自然地理与环境过程重点实验室，西宁 810008
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| 摘要: |
| 青藏高原主体海拔在4000 m以上，4000 m以上的人类活动与环境演变之间的关系研究很薄弱。本文通过对下大武遗址各粒级炭屑浓度的分析，试探讨其与人类活动和环境的关系。研究发现：（1）全新世大暖期时，气候温暖湿润，适宜生存。在对应的历史文化层中各粒级炭屑浓度出现高值区，说明此时下大武地区人类活动频繁，地方火和区域火频繁出现。（2）全新世中期，季风减弱，气候向冷干转变，植被退化，炭屑浓度普遍处于稳定的低值区，反映当时下大武地区人类活动的强度与范围缩小。（3）全新世晚期以来，3700—1800 cal.a BP炭屑浓度出现明显高值区，指示高原区域火的发生；1800 cal.a BP以来各粒级炭屑浓度波动频繁，粗粒炭屑浓度的波幅最大，指示下大武地区人类活动增强。 |
| 关键词: 炭屑 环境 人类活动 下大武 青藏高原 |
| DOI：10.7515/JEE201601003 |
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| 基金项目:国家自然科学基金项目（41550001，41161018） |
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| Charcoal concentration reflect of environment change and human activities in Xiadawu Relic, Qinghai-Tibet Plateau |
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ZHAO Yajuan, HOU Guangliang, E Chongyi, YANG long, WANG Qingbo1,2
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1. Key Laboratory of Qinghai-Tibet Plateau Environment and Resource, MOE, School of Life and Geographic Science, Qinghai Normal University, Xining 810008, China;2. Key Laboratory of Physical Geography and Environmental Processes of Qinghai Province, Qinghai Normal University, Xining 810008, China
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| Abstract: |
| Background, aim, and scope Fire as an unique and important ecological factor, both in past and present, has a significant impact on the environment. Charcoal is the direct product of fire and vegetation, it’s related to both climatic changes and human activities. Therefore, charcoal not only can be used to reconstruct ancient fire event, but also indicate the strength of human activities. Xiadawu site which is located on Tibetan Plateau with 4000 meters elevation has been excavated in 2007. However, the research on the relationship between the ancient climate and human activities is rarely. In this paper, we analyzed the concentration of each granular level of charcoal in Xiadawu site, and attempted to explore its relationship with human activities and the environment changes. Materials and methods Soil samples were collected for determination of charcoal. Heavy liquid flotation was used to isolate the charcoal, and pollen circuit method was used to count the charcoal which was separated from soil samples. According to the long axis of charcoal, charcoal samples were separated for grading: <50 μm (fines), 50 — 125 μm (medium grain) and >125 μm (coarse). Coarse-grained charcoal indicated local fire events, and fine-grained charcoal indicated region fire events with large area. Charcoal concentration reflected the intensity and frequency of the fire. Four charcoal samples were collected for radiocarbon dating. Results The results showed that: (1) The average concentration values of each grade showed obvious peak value during the Holocene Optimum Period and the Medieval Warm Period, fluctuated frequently. (2) The average concentration of fine-grained charcoal took a great proportion in the total concentration of charcoal, and the average concentration of coarse-grained charcoal was lowest. (3) In the whole profile, the average concentration of fine-grained charcoal reached maximum during 2200 cal.a BP. Discussion (1) During the Holocene Optimum Period, the climate was warm and wet, it was suitable for survival. The high concentration of each granular level of charcoal occured in the corresponding historical cultural layer, which indicated that human activity was frequent in Xiadawu at that moment, local and regional fire happened frequently. (2) During the mid-holocene, the climate conditions changed drier and colder, and vegetation began to degenerate with the weaking summer monsoon, and the concentration of charcoal was generally lay in the stable low-value zone, indicating that human activity intensity and range have greatly shrunk in Xiadawu at that moment. (3) Since late Holocene, human had relatively continuous and stable activities at the high elevation region above 4000 m a.s.l. The peak concentrations of charcoal were more closely related to human activities. Conclusions Changes in the average concentration of charcoal in Xiadawu region not only related to the natural environment, but also closely related to human activities. The average concentration values of each grade showed obvious peak value during the Holocene Optimum Period and the Medieval Warm Period, fluctuated frequently. (1) During the Holocene Optimum Period (7400 — 6200 cal.a BP), the climate was warm and wet, it was suitable for survival. The high concentration of each granular level of charcoal occured in the corresponding historical cultural layer, which indicated that human activity was frequent in Xiadawu at that moment, and local and regional fire event happened frequently. (2) During the mid-Holocene (6200 — 3700 cal.a BP), the climate conditions changed drier and colder, and vegetation began to degenerate with the weaking summer monsoon, and the concentration of charcoal was generally lay in the stable low-value zone, indicating that human activity intensity and range had greatly shrunk in Xiadawu at that moment. (3) Since late Holocene: 3700 cal.a BP—), this period can be divided into two stages: 3700 — 1800 cal.a BP and 1800 cal.a BP—. The average concentration of charcoal was gradually increasing, reached a peak in 2600 cal.a BP. The average concentration of fine-grained charcoal reached an unprecedented high value, indicating that the trend of the regional fire event enhanced. Meanwhile the average concentration of medium-grained and coarse-grained only reached a small peak, implying that during this period the regional in large scale area fire activity was obvious, but low occurring probability of the local fire. During 3000 — 1800 cal.a BP, relatively continuous and stable human activities at the high elevation region above 4000 m a.s.l implied permanent colony on high elevation. The peak concentrations of charcoal were more closely related to human activities. During 1800 — 750 cal.a BP, the average concentration of medium-grained and coarse-grained charcoal fell to 0 grain∙g−1, and the average concentration of fine-grained was still relatively high, indicating that during this period there was little local fire while the regional fire happened frequently. Near 630 cal.a BP, the average concentration of each grade of charcoal reached another peak, which maybe associated with human activity intensity. Recommendations and perspectives Changes in concentration index of charcoal during Holocene have a good correspondence with previous studies on the surrounding area. It indicates that charcoal concentration of different grain-size is a sensitive proxy to reconstruct the plaeocliamte change and human history of fire using. However, in this paper, we only use charcoal concentration without any other environmental index, which can not support our story strongly. Thus, it is necessary to use other environmental indicators for further verification. |
| Key words: charcoal environment evolution human activities Xiadawu Qinghai-Tibet Plateau |
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