Investigating the Potential of the Tree-ring δ18O Time Series of Pinus thunbergii in the Dendroarchaeological Study

The main content of dendroarchaeology is to assign the exact calendar year to each tree ring in archaeological wood. Each tree ring can be assigned a year because the pattern of ring-width time series (hereafter, ring-width chronology) is unique for each time period and the same tree species share the pattern. However, the lack of agreement between ring-width chronologies of Pinus thunbergii compared to other tree species makes it difficult to use the chronologies for dating. This study was conducted to verify the dating possibility of archaeological woods using tree-ring δ¹⁸O time series (hereafter, tree-ring δ¹⁸O chronology) instead of ring-width chronology. For the study, 7 P. thunbergii were selected from coastal dunes, and the ring-width and tree-ring δ¹⁸O chronologies were compared. The results showed that the agreement between ring-width chronologies were large statistical deviations (t-value: 0.6~12.5 / G value: 38~70%) as much as difficult for dating. On the other hand, the tree-ring δ¹⁸O chronologies showed reliable agreement between them as statistically (t-value: 4.3~6.4 / G value: 77~84%) and visually. Based on the results, it has been verified that the dating possibility of archaeological woods for P. thunbergii, which is a difficult tree species for dating in dendrochronology, can be greatly improved if the tree-ring δ¹⁸O chronology is applied.