Abstract: Through field observation and laboratory analysis, this study investigated the leaf growing pattern in Populus euphratica and its relationship with developmental stages and leaf nutrient contents. The results showed that the individual leaf index (leaf length/width ratio) had a significant negative correlation (P<0.01) with DBH (diameter at breast height), tree height and leaf area. Leaf shape index decreased with the increase of canopy level at all development stages, and decreased with the increase of number of minor branch nodes at different canopy levels of the same individuals. The total N, P and organic C contents of individual leaf were positively correlated with tree height and DBH; total K content had a significant negative correlation with tree height and DBH (P<0.01); leaf index had a significant negative correlation with the total P content (P<0.05) and a significant positive correlation with the total K content (P<0.01). These results suggested that leaf index in P. euphratica changed not only at different developmental stages, but also at different levels of the same canopy and at different nodes of the branches. Total N, P, K and organic C contents of the leaves mainly changed at different developmental stages. With the increase of DBH, leaf index decrease and leaf area increase, the total P, K contents of the leaves have an increase trend.

Key words: characteristic scale., spatial scale, landscape pattern, scale effect