Vegetation evolution on the central Chinese Loess Plateau since late Quaternary evidenced by elemental carbon isotopic composition  

作　　者：ZHOU Bin SHEN ChengDe ZHENG HongBo ZHAO MeiXun SUN YanMin 

机构地区：[1]School of Earth Science and Engineering, Nanjing University, Nanjing 210093, China [2]Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China [3]School of Ocean and Earth Science, Tongji University, Shanghai 200092, China [4]Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100,China

出　　处：《Chinese Science Bulletin》2009年第12期2082-2089,共8页

基　　金：Supported jointly by National Natural Science Foundation of China(Grant Nos.40802034and40830107);National Basic Research Program of China(Grant No.2007CB815906);the Postdoctoral Science Foundation of China(Grant No.20060400676)

摘　　要：There are many controversial issues in loess studies such as natural vegetation types on the Chinese Loess Plateau during the historical periods and the spatial and temporal evolution of C3/C4 plants. Elemental carbon isotopic composition (δ13Cec) in the loess section may offer new evidence for these problems. Elemental carbon (EC) is produced by incomplete combustion of vegetation, and its carbon isotopic composition has a very small difference from that of the formal vegetation, then δ13Cec can be used as a record to recover the changes of vegetation. Elemental carbon was extracted by applying the oxidation method from the loess-paleosol sequence in the central Chinese Loess Plateau, and its carbon isotope composition was analyzed by the isotope mass spectrometer. The results showed that the vegetation in this region was a mixed type of C3 and C4 plants, dominated with C3 plants in most of the time. Since late Quaternary, C3/C4 plants may not follow a simple glacial-interglacial cycle mode on the Chinese Loess Plateau, but showing fluctuations. C3 plants increased gradually in L4 period, and more C3 plants occurred during S3 period, and C4 plants increased again during L3―L2 periods, after that, C3 plants dominated again during S1―S0 periods. During periods of paleosol development, C3 plants were abundant in S3 and S1, and there were more C4 plants in S2 and S0. During periods of loess sedimen- tation, there were more C3 plants in L4 and L1, and there were more C4 plants in L3 and L2. On the or- bital timescale, the vegetation variations revealed by δ13Cec record are consistent with the results of pollen data and also similar to the results obtained by organic carbon isotopic composition since the last glacial period.There are many controversial issues in loess studies such as natural vegetation types on the Chinese Loess Plateau during the historical periods and the spatial and temporal evolution of C3/C4 plants. Elemental carbon isotopic composition （δ^13Cec） in the loess section may offer new evidence for these problems. Elemental carbon （EC） is produced by incomplete combustion of vegetation, and its carbon isotopic composition has a very small difference from that of the formal vegetation, then δ^13Cec can be used as a record to recover the changes of vegetation. Elemental carbon was extracted by applying the oxidation method from the Ioess-paleosol sequence in the central Chinese Loess Plateau, and its car- bon isotope composition was analyzed by the isotope mass spectrometer. The results showed that the vegetation in this region was a mixed type of C3 and C4 plants, dominated with C3 plants in most of the time. Since late Quaternary, C3/C4 plants may not follow a simple glacial-interglacial cycle mode on the Chinese Loess Plateau, but showing fluctuations. C3 plants increased gradually in L4 period, and more C3 plants occurred during $3 period, and C4 plants increased again during L3-- L2 periods, after that, Cs plants dominated again during S1 --S0 periods. During periods of paleosol development, C3 plants were abundant in S3 and S1, and there were more Ca plants in S2 and SO. During periods of loess sedimen- tation, there were more C3 plants in L4 and L1, and there were more C4 plants in L3 and L2. On the orbital timescale, the vegetation variations revealed by δ^13Cec record are consistent with the results of pollen data and also similar to the results obtained by organic carbon isotopic composition since the last glacial period.

关 键 词：碳同位素组成 黄土高原 植被演变 晚第四纪 元素碳 C4植物 C3植物 证明 

分 类 号：P736.211[天文地球—海洋地质] S157[天文地球—海洋科学]