Background and Objective: Tree species composition is a major feature of forest ecosystems and understanding the major factors that clarify patterns of diversity is an important objective for ecologists. The aim of this study was to investigate the relationship between species diversity in tree layer and some features of beech stand in savadkooh forest. Method: Field data from 24 circular 400 m2 sample plots in the inventory grid of 100 m × 150 m were used in beech stand. For characterizing tree-layer diversity, tree-layer species richness (SR), Shannon–Wiener diversity index and Hill's evenness index were used. Herb-layer species richness (herb-layer SR) was estimated in each plot. Diameter (DBH) and height, also crown diameter in beech trees were measured per sample plot. In addition, litter and humus layer thickness were measured at center and cardinal points of sampling points. Findings: Result showed a total of 7 tree species were recognized in 24 plots. Totally, 23 herbaceous plants belonging to 21 families were found distributing in different plots within forest which higher life form was presented by Hemicryptophytes. There was a significant difference between dominant and co-dominant layers regarding to tree species richness (SR) and Shanon-weaver diversity index (p < 0.01), and higher mean values belonged to the dominant layer. The herb-layer richness correlated significantly with litter thickness, whereas there was no correlation between other factors. SR of tree layer was negatively and significantly correlated with DBH and Height of beech trees and Shanon’s diversity and Hill’s evenness indices of tree layer were negatively correlated with beech frequency. Discussion: In general, it can be stated that the highest indicators of richness and tree diversity are observed in the upper floors of the target population, which can be due to competition, the nature of the tree species. It is recommended in forestry operations, the diversity of tree species in different floor to be considered.
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