Abstract:The difference in leaf stable carbon isotope discrimination (Δ) of 18 representative Schima superba provenances was investigated based on three p rove nance trails located at Jian’ou of Fujian Province and Chun’an and Qingyuan of Zhejiang Province, and the geographic variation pattern and the effects of trial site and provenances growth rate were studied. Significant differences in leaf Δ were observed among the provenaces, and the differences in leaf Δ value betw een the highest and lowest provenances reached 69%, 30%, and 37% in 3 exper imental sites, respectively. A classic latitudinal clinal variation pattern was found, because there were significant correlations between the leaf Δ value and the latitude of seed sources in all the 3 sites while no significant correlatio ns were observed between the leaf Δ value and the longitude of the seed sources . The southern provenances showed higher leaf Δ value than the northern provena nces, indicating that the water use efficiency (WUE) was lower in southern prove nances. The leaf Δ value of different provenances was demonstrated to be greatl y affected by the environment of trial sites. The leaf Δ value increased signif icantly with the improvement of site environment and with the increase of annual rainfall. Significant positive correlations were observed between the leaf Δ v alue and the growth traits including tree height, DBH, total number of lateral b ranches, and length of the strongest lateral branch, which indicated that the pr ovenances with higher growth rate and denser crown had larger leaf Δ value. Two and four superior provenances with high growth rate and low leaf Δ value (or h igh WUE) were selected for Jian’ou of Fujian and Chun’an of Zhejiang, respecti vely.