青藏高原南部湖泊记录的晚全新世植被演化过程  

VEGETATION EVOLUTION RECORDED BY LAKE SEDIMENT DURING LATE HOLOCENE ON THE SOUTHERN TIBETAN PLATEAU

作　　者：简安璟 李昀卿 刘斯瑶 陈美娇 曹维予 孙喆 侯居峙[3,4] 田芳 JIAN Anjing;LI Yunqing;LIU Siyao;CHEN Meijiao;CAO Weiyu;SUN Zhe;HOU Juzhi;TIAN Fang(College of Resource Environment and Tourism,Capital Normal University,Beijing 100048;Institute of Geography and Resources Science,Sichuan Normal University,Chengdu 610066,Sichuan;Group of Alpine Paleoecology and Human Adaptation(ALPHA),Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100101;State Key Laboratory of Tibetan Plateau Earth System,Environment and Resources(TPESER),Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100101)

机构地区：[1]首都师范大学资源环境与旅游学院,北京100048 [2]四川师范大学地理与资源科学学院,四川成都610066 [3]中国科学院青藏高原研究所,古生态与人类适应团队,北京100101 [4]中国科学院青藏高原研究所,青藏高原地球系统与资源环境全国重点实验室,北京100101

出　　处：《第四纪研究》2024年第3期742-754,共13页Quaternary Sciences

基　　金：国家自然科学基金项目(批准号:42071107)资助。

摘　　要：青藏高原是我国重要的生态安全屏障,其生态系统安全是实现高原可持续发展的基础。植被覆盖度是评价植被状况的重要指标,研究其演变过程及机制具有重要意义。本研究选择青藏高原南部昂仁金错沉积岩芯(长120 cm)作为研究对象,基于可靠的AMS ^(14)C年代序列和孢粉记录,研究距今3600年以来的植被变化过程;选用青藏高原南部614个现代孢粉和植被覆盖度数据并基于现代类比法(MAT)构建校准集,交叉检验表明模型可靠性较高(R^(2)=0.71,RMSE=8.51%),可用于定量重建植被覆盖度演化过程。研究结果表明,昂仁金错晚全新世沉积物孢粉组合以草本植物花粉为主,主要包括莎草科、蒿属、禾本科、毛茛科等花粉类型。3600~850 cal.a B.P.期间,莎草科花粉占优势,表明湖泊周围发育了植被覆盖度较高的高寒草甸,气候较为湿润;而850 cal.a B.P.以来,蒿属花粉含量不断增加,表明植被向高寒草原转变,覆盖度显著降低。经区域多记录对比发现,该时期植被类型的转变为区域性现象,应代表了印度夏季风减弱和气候变干的整体趋势。As a significant ecological security buffer of China,the preservation of the ecosystem on the Tibetan Plateau(TP)is vital for sustainable development.Vegetation coverage is crucial in assessing the health of the flora on the TP,hence it is essential to comprehensively investigate the evolutionary processes and underlying mechanisms.In this study,a 120 cm-long sedimentary core was collected from Ngamring Co(29°17'~29°20'N,87°09'~87°13'E;4304 m a.s.l.),at a water depth of 13 m.We chose AMS ^(14)C and ^(210)Pb/^(137)Cs approaches to establish the age-depth model.Dating results indicate that the reservoir effect was 1999 years for AMS 14C dates,and the core covered the last 3600 years.Pollen analysis was conducted to reconstruct the historical evolution of vegetation with a temporal resolution of 30 years per sample.Utilizing the Modern Analogue Technique(MAT),a calibration-set was established based on modern pollen percentages and vegetation coverage from 614 sampling sites on the southern TP(unpublished data from our team).The"leave-one-out"cross-validation results indicate that this model is reliable(R^(2)=0.71,RMSE=8.51%)and can be used to quantitatively reconstruct changes in vegetation coverage.In total,64 pollen taxa have been identified in the 120 fossil pollen samples.The pollen spectra were dominated by herbaceous pollen taxa,including mainly Cyperaceae,Artemisia,Chenopodiaceae,Poaceae,and Ranunculaceae.The proportions of tree pollen were lower,and Pinus,Betula,Tsuga,and Quercus occur commonly.The shrub pollen types include mainly Rosaceae,Nitraria,Hippophae,and Ephedra.During 3600~850 cal.a B.P.,the pollen spectra were primarily composed of Cyperaceae,with the A/Cy ratio(ratio of Artemisia to Cyperaceae)<1,indicating the presence of alpine meadow vegetation around the lake with relatively high vegetation coverage(mean 16.9%)in a wet climatic condition.Additionally,the scores of the first axis of PCA were significantly negative at ca.3300 cal.a B.P.,and the vegetation coverage was significantly reduced,

关 键 词：昂仁金错 孢粉 植被覆盖度 现代类比法 

分 类 号：Q944.571[生物学—植物学] P534.632[天文地球—第四纪地质学] P941.78[天文地球—古生物学与地层学]