• 责任者：Zhao De’a (Key Laboratory of Cenozoic Geology and Environment ; Institute of Geology and Geophysics ; Chinese Academy of Sciences ; Beijing 100029 ; China) ; Wu Haibin
• 刊名：Quaternary Sciences
• 出版年：2013
• 卷期：33(5)
• 关键词：有机碳 ; organic carbon ; 植物群研究 ; floral studies ; 黄土高原 ; Loess Plateau
• 页码：p.848-855
• 图表：5 illus., 50 refs.
• 分类号：1400
• issnNo：ISSN1001-7410
• isbnNo：CN11-2708/P

     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 Interglacial.The values of the Middle Holocene are more positive than present and even Last Interglacial.The values of the western part also show similar trend with the east during the Middle Holocene and can be reached -20.9‰ .However,during the Last Interglacial period,the δ13Corg. values of the west part of CLP are more negative than present,and values can reach -24.8‰,which is even more negative than the Last Glacial,opposing trends to the changes in the east region.The organic carbon isotopes of both east and west Loess Plateau show consistent variation tendency with positive amplitude of 2.2‰ -2.9‰ comparing to the Last Glacial Maximum（LGM）,indicating the increase of the biomass of C4 grass.However,it shows a different variation in the east and west during the Last Interglacial.The eastern and western tablelands show a positive tendency while the east part shows a positive value of 0.9‰-4.0‰,indicating the increase of the C4 grass.In the western loess hill,the data shows a negative value of 0.8‰,which indicating the decrease of C4 plants.As these two periods have similar atmospheric CO2 concentration and the temperature had increased,the differences of the biomass of C4 vegetation between east and west can be attribute to the increasing of precipitation and seasonality.This study shows the evolution of vegetation is significantly distinct in the eastern and western Loess Plateau under different warming amplitudes.In this context,we took these two periods as analogues for the warming future.Regardless of the effects of atmospheric CO2 concentration changes and human activities,the biomass of C4 grasses in the eastern and western tablelands of Loess Plateau would increase along with global warming; in the western loess hill,a trend of first increase then decrease would occur.