晚中新世植被变更与光合作用演化  

VEGETATION CHANGE IN LATE MIOCENE AND EVOLUTION OF PHOTOSYNTHESIS

作　　者：贺娟[1] 汪品先[1] 

机构地区：[1]同济大学海洋地质国家重点实验室,上海200092

出　　处：《地球科学进展》2005年第6期618-626,共9页Advances in Earth Science

基　　金：国家重点基础研究发展规划项目"地球圈层相互作用中的深海过程和深海记录"(编号:G2000078500)资助.

摘　　要：光合作用酶Rubisco出现于太古代,对于以后地质时期里大气的CO2降低并不适应。晚中新世大幅度扩展的C4植物,就是光合作用演化的一种途径,适应于CO2浓度较低的大气,也适应于温暖而季节性干旱的季风气候。C4与C3植物碳同位素的重大差异,又为利用古土壤和哺乳类牙齿珐琅质的δ13C分辨C3、C4植物在植被中的比例提供了条件。自从发现巴基斯坦晚中新世古土壤层δ13C突变以来的10余年,围绕着C4植物扩展究竟反映季风气候,CO2浓度下降,还是干旱化,国内外学术界展开了热烈的讨论,至今尚属未解之谜,但从中可以吸取研究地球系统演变的经验教训。Rubisco, an ancient photosynthetic enzyme of Archean origin, became increasingly inefficient with reduction of atmospheric CO_(2) levels in the later geological history. The remarkable expansion of C_(4) biomass in late Miocene was an adaptive evolution in photosynthesis, as C_(4) photosynthesis was more adaptive to the lower concentration of CO_(2), as well as to monsoonal climate with warmer temperature and seasonal aridity. Given the significant difference in carbon isotope between C_(3) and C_(4) plants, the δ^(13)C of paleosols and mammalian tooth enamels was widely used as an indicator of proportions of C_(3) to C_(4) plants in vegetation. Since the discovery of the dramatic shift of δ^(13)C in the late Miocene paleosol from Pakistan over 10 years ago, the expansion of C_(4) biomass then has become a matter of hot debate within the scientific community: whether it was caused by monsoon climate, decreasing atmospheric CO_(2) level, or aridification?Though it remains an enigma up to now, there are useful lessons to be drawn from a brief review of the story as presented in this paper.

关 键 词：C4植物 C3植物 RUBISCO 光合作用 晚中新世 

分 类 号：P5[天文地球—地质学]