A biometrical study carried out in Oak Forests in Northern Zagros, west of Iran. This study aimed to evaluate the response of biometrical indices of Quercus SPP. to aspect variations in Northern Zagros Forests. Data collected systematic-randomly from 319 circular plots (each 0.1 ha in size) during 2003. Chi-square test was used to compare species combinations in different geographical directions. One-way ANOVA and Duncan test were preformed to compare the basal area among the different geographical directions. Height, diameter, and canopy area of the dominant trees (i.e. Quercus libani Oliv., Quercus brantii Lindl. and Quercus infectoria Oliv.) were compared using, Kruskal-Wallis H and Mann-Whitney U tests. Results, showed that, trees combinations were differ significantly between different geographical directions(P < 0.05) as well as diameter of the dominant trees (exclusive geographical direction) (P< 0.01). The basal area in northern and southern forests was considerably different (P< 0.05). No difference was observed in tree heights amongst the different geographical directions. The height of the dominant trees (exclusive geographical direction) were differ (P< 0.01). There was no significant difference in canopy area between different geographical directions (P = 0.191), while it was differ amongst the dominant trees (exclusive geographical direction) (P< 0.01).
