Relationship between climatic conditions and the relative abundance of modern C3and C4plants in three regions around the North Pacific

摘要

Using -24‰ and -14‰ as the endpoints of stable carbon isotopic composition of total organic carbon (δ 13 C TOC ) of surface soil under pure C 3 and C 4 vegetation, and surface soil δ 13 C TOC data from eastern China, Australia and the Great Plains of North America, we estimate the relative abundance of C 3 /C 4 plants (i. e., the ratio of C 3 or C 4 biomass to local primary production) in modern vegetation for each region. The relative abundance of modern C 3 /C 4 vegetation from each region is compared to the corresponding climatic parameters (mean annual temperature and precipitation) to explore the relationship between relative C 4 abundance and climate. The results indicate that temperature controls the growth of C 4 plants. However, even where temperature is high enough for the growth of C 4 plants, they will only dominate the landscape when precipitation declines as temperatures increase. Our results are consistent with those of other investigations of the geographic distribution of modern C 4 plant species. Therefore, our results provide an important reference for interpretation of past C 3 /C 4 relative abundance records in these three regions. © 2010 Science China Press and Springer-Verlag Berlin Heidelberg.