[S-GL22] Geochronology and Isotope Geology

[SGL22-P01] Exploring the use of Asiu cedar carbon isotopic ratios as paleoclimate reconstruction

*yuga kondo¹, Yumiko Watanabe (1.Kyoto University )

Keywords:carbon isotopic ratios, tree ring, tree ring width

Cellulose oxygen isotope ratios of Ashiu cedar collected at northeastern Kyoto were measured and compared them with meteorological data to verify their potential as a hydroclimate proxy (Watanabe et al., 2023). They discussed oxygen isotope ratios of Ashiu cedar in detail, but did not examine the usefulness of other tree-ring data as a paleoclimate proxy. Therefore, in this study, we measured ring widths for Ashiu cedar sample and examined their correlation with meteorological data. In addition, carbon isotopic ratios were also performed correlation analysis with meteorological data to gain a comprehensive understanding of the climatological significance of the tree ring data.

The results show that there was little correlation between ring width and relative humidity or precipitation. This may be due to the fact that physiological and ecological factors had more influence on the variation of ring width than climatic factors. On the other hand, a weak negative correlation was observed between ring width and carbon isotopic ratios. This might be due to the fact that the growth environment of the samples was dry, and thus the weight of water stress as a growth factor was high. Although there was no significant correlation between carbon isotopic ratios and relative humidity or precipitation, a significant negative correlation between relative humidity and precipitation was found by using the correction equation. These results indicate that Ashiu cedar carbon isotopic ratios could be a useful paleoclimate proxy when correction equations are used.