摘要
过去典型增温时段的自然植被演化规律是未来增温情形下植被变化趋势的重要参照。黄土高原全新世中期(4~8kaB.P.)和末次间冰期(80~110kaB.P.)温度分别比现高约1.2℃和2~5℃,是揭示过去不同增温幅度下植被演化的理想时段。通过对黄土高原东西部黄土-古土壤序列有机碳同位素(δ^(13)C_(org.))对比研究表明:在全新世中期黄土高原东西部有机碳同位素变化一致,相对末次盛冰期表现为正偏2.2‰~2.9‰,指示C_4植物丰度增加。而在末次间冰期黄土高原东、西部不同地貌单元有机碳同位素结果产生空间分异,相对末次盛冰期西部梁峁区表现为负偏约0.8‰,指示C_4植物丰度减少,而东部塬区则表现为正偏0.9‰~4.0‰,指示C_4植物丰度增加。由于上述典型时段大气CO_2浓度相近且温度升高,末次间冰期与全新世中期黄土高原C_4植物丰度变化的差异可能与降水增加的季节性变化有关。上述结果表明,在过去典型增温期不同增温幅度下黄土高原东、西部不同地貌单元植被演化呈现明显不同。
The characteristics of the natural vegetation evolution during typical warming periods in the past reconstructed by organic carbon isotope may not only attribute to understand the driving mechanism during past climate change,but also improve knowledge for predicting plants＇ evolution in the future. The temperature of Loess Plateau during the Middle Holocene（4-8kaB.P.）and the Last Interglacial（80-110kaB.P.）is 1.2℃ and 2-5℃ higher than present,respectively.These two periods are ideal analogues to discuss the possible vegetation evolution trend within different warming magnitude.We systematically collected the data of organic carbon isotope composition from Luochuan（35°47＇N,109°26＇E）,Xunyi（35°14＇N,108°24＇E）,and Lantian（34°12＇N,109°12＇E）,and Yuanbu（35°38＇N,103°09＇E） loess-paleosol sequences,and added a new Zhouzhuang-Zhangwan section on the west of Loess Plateau to better understand the palaeovegetation evolution for the whole Loess Plateau.Zhouzhuang section（35°02＇N,105°28＇E） is located in the northeastern part of Tianshui City,while Zhangwan section（34°41＇N,105°45＇E） is 46km away on the southeast direction of Zhouzhuang.The top part of the two sections was disturbed by modern agricultural activities.The Holocene paleosol layer of Zhangwan section was entirely eroded.We systematically collected the samples of Zhouzhuang section from S0 to L1 and Zhangwan section from L1 to S1 at 2cm intervals in the upper 4 meters and 5cm intervals below.In order to obtain a complete section since the Last Interglacial,we connected the two sections through magnetic susceptibility indoor.For δ13Corg.,samples were measured by Picarro CM-CRDS.The results of standard materials（n=12）demonstrated that the standard deviation of the instrumental measurement is ≤±0.2‰ （V-PDB）.In the east part of CLP,the δ13Corg. values are more positive than present and can be reached as much as -17.1‰ in the southeast and -20.4‰ in the northeast during the Last Inte
出处
《第四纪研究》
CAS
CSCD
北大核心
2013年第5期848-855,共8页
Quaternary Sciences
基金
国家重点基础研究发展规划项目(973项目)(批准号:2010CB50205)
国家自然科学基金面上项目(批准号:21171250)共同资助
