Abstract: In this study,the diversifolious types and spatial distribution of Populus pruinosa Schrenk under the same site conditions in the northwestern marginal zone of the Tarim Basin were researched so as to reveal the growing and vertical distribution of heterophylls of P.pruinosa with the variation of diameter class stage as well as their relationship. The results are as follows: ① Broad oval leaves,round leaves and broad ovate leaves turned regularly and grew at different diameter class stages when broad oval leaves grew at 2-20 diameter class stage,while round leaves and broad ovate leaves grew from 4 and 6 diameter class stages,and they grew from the top canopy. Growth of heterophylls was associated with the individual developmental stages; ② The growing frequencies and the proportions of heterophylls at the vertical spatial distribution areas in the canopy height changed dynamically with the change of diameter class stage,in which the growing frequency and the proportion of broad oval leaves at the vertical spatial distribution area in the canopy height were gradually decreased with the increase of diameter class stage,those of round leaves were increased at first and then decreased with the increase of diameter class stage,and those of broad ovate leaves were gradually increased with the increase of diameter class stage; ③ There were the extremely significant negative correlations between the growing frequency in vertical space of canopy and the proportion of vertical spatial distribution in canopy height with the diameter at breast height and the tree height for broad oval leaves,and the extremely significant positive ones for both round leaves and broad ovate leaves. These revealed that the growing frequency and spatiotemporal variation of various heterophylls were closely related to the ontogenetic stage of P.pruinosa.

Key words: Populus pruinosa, heterophylly, diameter class stage, spatiotemporal variation