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Relationship between the stable carbon isotopic composition of modern plants and surface soils and climate: A global review

Rao, Zhiguo, Guo, Wenkang, Cao, Jiantao, Shi, Fuxi, Jiang, Hong, Li, Chaozhu
Earth-science reviews 2017 v.165 pp. 110-119
C3 plants, C4 plants, carbon, climatic factors, correlation, soil, stable isotopes, temperature, vegetation, China
Analysis of the stable carbon isotopes (δ13C) in organic material in various geological archives has been widely used for paleoclimatic reconstruction. Consequently, it is important to characterize the δ13C values of modern plants and surface soils to provide analogues for strengthening paleoclimatic reconstructions. In this paper, >10.000 previously reported δ13C values from modern plants and surface soils at globally distributed sites, together with newly obtained surface soil δ13C data from 107 sites in inland China, are used to establish relationships with corresponding mean annual temperature (MAT) and precipitation amount (MAP). Using a δ13C value of −24‰ of surface soil as the discriminator between pure C3 vegetation and C3/C4 mixed vegetation, our results demonstrate a close relationship between MAT and C4 relative abundance, implying that temperature is the primary climatic factor determining the C3/C4 relative abundance. Both the δ13C values of modern C3 plants and surface soils under pure C3 vegetation are significantly negatively correlated with MAP, confirming that the δ13C of material sourced from pure C3 vegetation can be used for paleoprecipitation reconstruction. However, unlike C3 plants, the δ13C values of modern C4 plants are significantly positively correlated with MAP. Thus our results can serve as a reference for the paleoclimatic interpretation of sedimentary δ13C data.