Effect of Physiographical Factors on Plant Species Diversity in Forests of Western Bodjnourd (North of Iran)

This investigation has been conducted to determining plant species diversity in relationship to the physiographical factors in western Bodjnourd forests (North of Iran). To cope with the aim of study, 220 ha of these forests (called Joezak-Darkesh forest) at 1400-2000 m a.s.l. with different geographical aspects and slope steeps of 0-80 percent were identified. Number of 55 sample plots of 20 × 20 m as random-systematic distribution was selected to determination of the trees and shrubs. In addition, within each plot 9 micro-plots 2 × 2 m were confined to recognition of ground non-woody flora. The highest value of species similarity was obtained between two low height classes (