I. Robertson et al., SIGNAL STRENGTH AND CLIMATE RELATIONSHIPS IN C-13 C-12 RATIOS OF TREE-RING CELLULOSE FROM OAK IN SOUTHWEST FINLAND/, Geophysical research letters, 24(12), 1997, pp. 1487-1490
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.