Inter-tree correlation and climatic response of tree-ring δ18O in Chinese fir: Implications for cross-dating and climatic reconstruction in Central East China

The availability of both ancient and modern wood samples enables the Chinese fir (Cunninghamia lanceolata) in Central East China to become a potential tree species for dendroclimatic reconstruction over the Common Era. However, the potential of using tree-ring α-cellulose oxygen isotope ratios (δ¹⁸O_TRC) in Chinese fir for the purposes of cross-dating and climatic reconstruction remains unexplored. Here we presented three δ¹⁸O_TRC chronologies (1954–2006 CE) for the whole-ring (δ¹⁸O_WR), earlywood (δ¹⁸O_EW), and latewood (δ¹⁸O_LW) in Chinese fir. The results indicated that the δ¹⁸O_WR had the highest correlation among individual trees. Using the δ¹⁸O_WR instead of the conventionally employed TRW can facilitate the cross-dating procedure. The δ¹⁸O_WR, δ¹⁸O_EW, and δ¹⁸O_LW exhibited the strongest relationships with the hydroclimate variables during the entire (June–September), early (June–July), and late (August–September) summer, respectively. The climate conditions preceding the growing season had a stronger influence on δ¹⁸O_EW than δ¹⁸O_LW. Using the δ¹⁸O_WR and δ¹⁸O_EW to reconstruct the hydroclimate variations may result in greater bias than the use of δ¹⁸O_LW. Our study demonstrated that the δ¹⁸O_TRC in Chinese fir from Central East China has the potential for cross-dating and summer hydroclimate reconstruction.