Abstract: By field observation and laboratory analysis, we investigated carbohydrate, soluble protein and morphometric changes of leves of Populus euphratica Oliv. individuals under different developmental stages. With the increase of DBH(age) and canoy levels, leaf index decreased gradually with a very significant negative correlation among leaf index, DBH and tree height. Leaf soluble sugar contents kept steadily in superior level under different developmental stages and canoy levels. But it had no correlation with individual development stages. There were a significant, very significant negative and positive correlations with leaf starch contents, DBH, leaf index, and leaf width, respectively. There were a significant and very significant positive correlation with the leaf soluble protein contents, leaf index, and leaf length, respectively. By comprehensive analysis, leaf change of P.euphratica individual not only existed in different development stages, but also in canoy levelLeaf changes of P.euphratica(heterophylly) is the biological cs. haracteristics under different developmental stages.The leaf indexes deceased with the increase of developmental stages and canoy levels. With the increase of DBH and the decease of leaf index and leaf width, the leaf starch contents decreased gradually. With the decease of leaf index and the increase of leaf length, leaf soluble protein contents decrease gradually. Starch and soluble protein metabolism of P.euphratica leaf had a regulating effect on leaf length and width change.

Key words: Populus, leaf index, soluble sugar, starch, soluble protein