Inter- and intra-annual tree-ring cellulose oxygen isotope variability in response to precipitation in Southeast China

Compared with annual tree-ring cellulose delta (18) O, intra-annual cellulose delta (18) O has potential to reconstruct precipitation with higher resolution and stronger signal intensity. Annual tree-ring cellulose oxygen isotope values (delta O-18) of Fokienia hodginsii provide a promising proxy of monsoon-season precipitation in Southeast China. Measuring intra-annual cellulose delta O-18 values may reveal the seasonal variability of precipitation and the associated climate influences. Here, we examine intra-annual variation of cellulose delta O-18 values in Fokienia hodginsii and Cryptomeria fortune from Fujian Province, Southeast China. Both species exhibited considerable intra-annual variations in cellulose delta O-18 (range similar to 6 aEuro degrees) with a consistent pattern of enriched values near the annual ring boundary and depleted values in the central portion of the ring. Seasonal patterns in the tree-ring delta O-18 values generally followed changes in precipitation delta O-18 values. Compared with annual tree-ring cellulose delta O-18, intra-annual cellulose delta O-18 has potential to reconstruct precipitation with higher resolution and stronger signal intensity. July tree-ring cellulose delta O-18 is significantly correlated (r = -0.58, p < 0.05) with July precipitation, and June-August tree-ring cellulose delta O-18 and annual tree-ring cellulose delta O-18, respectively, explain 52 and 41 % of the actual variance of April-August precipitation. In addition, May-October cellulose delta O-18 values during El Nio years are higher than in La Nia years, and April to October rainfall is lower in El Nio years than in La Nia years. Combining the significant correlations between inter-annual cellulose delta O-18 values and sea surface temperatures in the central tropical Pacific, our results support the hypothesis that El Nio-Southern Oscillation affects tree-ring cellulose delta O-18 in Southeast China by modulating seasonal precipitation.