A. Salehi - Department of Forestry, Natural Resources Faculty, University of Guilan, P.O. Box ۱۱۴۴, Somesara,
M. Heydari - S. Arekhi۱ , M. Heydari۲, H. Pourbabaei۲ ۱- Dept. of Range and Forest, Faculty of Agriculture, University of Ilam, Ilam, Iran ۲- Dept. of Forestry, Faculty of Natural Resources, University of Guilan, Someh Sara, P.O. Box ۱۱۴۴, Iran *Correspondi
H. Poorbabaei - M. Heydari ۱ , H. Poorbabaei۱, T. Rostami۱, M. Begim Faghir۲, A. Salehi۱, R. Ostad Hashmei۱
T. Rostami - M. Heydari ۱ , H. Poorbabaei۱, T. Rostami۱, M. Begim Faghir۲, A. Salehi۱, R. Ostad Hashmei۱
M. Begim Faghir - M. Heydari ۱ , H. Poorbabaei۱, T. Rostami۱, M. Begim Faghir۲, A. Salehi۱, R. Ostad Hashmei۱
R. Ostad Hashmei - M. Heydari ۱ , H. Poorbabaei۱, T. Rostami۱, M. Begim Faghir۲, A. Salehi۱, R. Ostad Hashmei۱

The present survey was carried out in Oak (Quercus brantii Lindl.) woodlands of Arghvan valley protected area, in Ilam province, western Iran. The main aim of this study was to survey the understory vegetation of oak in different classes of altitude (۱۴۰۰-۱۶۰۰, ۱۶۰۰-۱۸۰۰ and >۱۸۰۰ m) in the southern aspects, and their relationship with physical and chemical properties of soil. Four transects, with an interval of ۲۰۰ m were selected from the lowest to the highest points of hillside. ۲۵ individual oak trees were selected on and out of the transects as a plot center. The plot area was obtained using Whittaker?s nested plots and species / area curve. In order to find the relationship between soil properties and vegetation, and also to determine the most effective factors on the distribution of vegetation, multivariate procedures, i.e., Principal Component Analysis (PCA) and Canonical Correspondence Analysis (CCA) were used. Based on these analyses three groups were obtained. These groups exactly coordinated with our sample plots in altitudinal classes and had different soil and vegetation characteristics. The most important factors in the lowland group were pH, SP, OC, N,P and K, and those in the highland group were altitude, BD and stone percentage. The midland group was intermediate to these two groups, although its conditions were more similar to the highland group. The results also indicated a decrease in Shannon-Weiner and Margalef?s indices from lowland toward the highland.

Oak, vegetation understory, Site classification, altitude, Zagros, Iran