气候变化领域集成服务门户

Using -24% and -14% as the endpoints of stable carbon isotopic composition of total organic carbon (delta C-13(TOC)) of surface soil under pure C-3 and C-4 vegetation, and surface soil delta C-13(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.