Spatial and temporal variations of C_3/C_4 relative abundance in global terrestrial ecosystem since the Last Glacial and its possible driving mechanisms  

作　　者：RAO ZhiGuo CHEN FaHu ZHANG Xiao XU YuanBin XUE Qian ZHANG PingYu 

机构地区：[1]Key Laboratory of Western China's Environmental Systems(Ministry of Education),Lanzhou University,Lanzhou 730000,China

出　　处：《Chinese Science Bulletin》2012年第31期4024-4035,共12页

基　　金：supported by the National Basic Research Program of China (2010CB950202);the Key Project of the Chinese Ministry of Education(109151);the National Natural Science Foundation of China (40901055and 41171091);the Fundamental Research Funds for the Central Universities of Lanzhou University (lzujbky-2012-k49);the Program for New Century Excellent Talents in University (NCET-10-0468)

摘　　要：The primary factor controlling C 3 /C 4 relative abundance in terrestrial ecosystem since the Last Glacial has been widely debated. Now more and more researchers recognize that climate, rather than atmospheric CO 2 concentration, is the dominant factor. However, for a specific area, conflicting viewpoints regarding the more influential one between temperature and precipitation still exist. As temperature and precipitation in a specific area usually not only vary within limited ranges, but also covary with each other, it is difficult to get a clear understanding of the mechanism driving C 3 /C4 relative abundance. Therefore, systematic analysis on greater spatial scales may promote our understanding of the driving force. In this paper, records of C3/C4 relative abundance since the Last Glacial on a global scale have been reviewed, and we conclude that: except the Mediterranean climate zone, C3 plants predominated the high latitudes during both the Last Glacial and the Holocene; from the Last Glacial to the Holocene, C4 relative abundances increased in the middle latitudes, but decreased in the low latitudes. Combining with studies of modern process, we propose a simplified model to explain the variations of C3 /C4 relative abundance in global ecosystem since the Last Glacial. On the background of atmospheric CO2 concentration since the Last Glacial, temperature is the primary factor controlling C3/C4 relative abundance; when temperature is high enough, precipitation then exerts more influence. In detail, in low latitudes, temperature was high enough for the growth of C4 plants during both the Last Glacial and the Holocene; but increased precipitation in the Holocene inhibited the growth of C4 plants. In middle latitudes, rising temperature in the Holocene promoted the C4 expansion. In high latitudes, temperature was too low to favor the growth of C4 plants and the biomass was predominated by C3 plants since the Last Glacial. Our review would benefit interpretation of newly gained records of C3/C4 relative abundancThe primary factor controlling C3/C4 relative abundance in terrestrial ecosystem since the Last Glacial has been widely debated. Now more and more researchers recognize that climate, rather than atmospheric CO2 concentration, is the dominant factor. How- ever, for a specific area, conflicting viewpoints regarding the more influential one between temperature and precipitation still exist. As temperature and precipitation in a specific area usually not only vary within limited ranges, but also covary with each other, it is difficult to get a clear understanding of the mechanism driving C3/C4 relative abundance. Therefore, systematic analysis on greater spatial scales may promote our understanding of the driving force. In this paper, records of C3/C4 relative abundance since the Last Glacial on a global scale have been reviewed, and we conclude that： except the Mediterranean climate zone, C3 plants predominated the high latitudes during both the Last Glacial and the Holocene; from the Last Glacial to the Holocene, C4 relative abundances increased in the middle latitudes, but decreased in the low latitudes. Combining with studies of modem process, we propose a simplified model to explain the variations of C3/C4 relative abundance in global ecosystem since the Last Glacial. On the background of atmospheric CO2 concentration since the Last Glacial, temperature is the primary factor controlling C3/C4 rela- tive abundance; when temperature is high enough, precipitation then exerts more influence. In detail, in low latitudes, temperature was high enough for the growth of Ca plants during both the Last Glacial and the Holocene; but increased precipitation in the Holocene inhibited the growth of Ca plants. In middle latitudes, rising temperature in the Holocene promoted the Ca expansion. In high latitudes, temperature was too low to favor the growth of C4 plants and the biomass was predominated by C3 plants since the Last Glacial. Our review would benefit interpretation of newly gained records of C3/C4 relative abundance

关 键 词：陆地生态系统 末次冰期 相对丰度 驱动机制 时空变化 大气CO2浓度 温度升高 高纬度地区 

分 类 号：Q14[生物学—生态学]