Stable carbon isotopes of woods during carbonization and their correlation with climatic factors

To explore the applicability of the carbon isotope composition ([delta].sup.13 C) of fossil charcoal for the quantitative reconstruction of paleoclimates, we selected five points in Shaanxi province, from north to south, to collect modern Pinus species and Quercus species to sample covering areas with obvious climatic differences. In order to reveal the relationships between [delta].sup.13 C of charcoal and climate variables on the basis of carbonization experiments, we evaluated the fractionation mechanism of [delta].sup.13 C of charcoal, and compared the differences between [delta].sup.13 C of charcoal in wildfire experiments and indoor experiments regarding genera and species. The results showed significant differences in [delta].sup.13 C between genera but no significant differences among species. Additionally, the [delta].sup.13 C of charcoal was significantly negatively correlated with precipitation and positively correlated with evaporation, which could be determined from [delta].sup.13 C values in the study area to reconstruct ancient precipitation and evaporation in the future.