SIGNAL STRENGTH AND CLIMATE RELATIONSHIPS IN C-13 C-12 RATIOS OF TREE-RING CELLULOSE FROM OAK IN SOUTHWEST FINLAND/

Annual oak (Quercus robur L.) latewood delta(13)C values are presented for the period 1895-1994 for two sites different hydrological charact eristics in southwest Finland. No appreciable anthropogenic C-13 deple tion was observed in the time-series. delta(13)C indices record high-f requency common forcing better than lower-frequency forcing. High-freq uency fluctuations in the delta(13)C indices are highly correlated wit h climatic variables. Cross correlation analysis of tree ring delta(13 )C indices and climate variables show that there is no significant dif ference (p<0.01) in the climate response of tree ring delta(13)C indic es between the two sites. This work demonstrates that significant clim ate signals are contained in isotopic measurements of trees whose ring -widths contain little or no such information.