Studies on circumferential δ 13 C variability in tree ring have been reported.Despite a variety of species and localities,the range of δ 13 C around the circumference of tree ring is typically 0.1%～ 0.4% .However,studies on climatic implications for the difference among radii in tree rings have not yet been reported.In this paper,four trees sampled from different localities(three from Tianmushan Mount.and one from Lushan Mount.)were analysed.More than 7 radii with forty five degree interval from each tree were analyzed.The results showed that δ 13 C differences among radii reached 0.17%,but the directions for the lowest and the highest were different for each tree.The difference among radii in δ 13 C variance to the circumferential difference was in the same order of magnitude.By analyzing the δ 13 C climate relationship,the δ 13 C differences among radii may be used to study more climatic implications.