Investigating the interaction between trees abundance and some environmental factors in beech forests(case study: beech forest of Savadkoh-Mazandaran)

The aim of this study was to investigate the relationship between tree- and herb-layer regading to some variables in Hyrcanian beech forest, Northern Iran. For this research, field data from 24 circular 400 m2 sample plots in the inventory grid of 100 m × 150 m were used in beech stand. All trees with a diameter at breast 2 cm in each plot were measured to determine the frequency. Herb-layer species richness (herb-layer SR) was estimated in each plot. Humus layer thickness were measured at center and 4 corners of sampling points. The results showed that the humus thickness was significantly positively correlated with beech frequency (P=0.009) but there was no significant relationship with other tree species. Herb layer was significantly negatively correlated with maple frequency. Beech frequency was significantly positively correlated with hornbeam trees (P=0.036), and as well as negatively with maple (P=0.000) and alder trees (0.036). Analysis of variance showed that the altitude had no effect on trees abundance in deciduous braod-leaf forest.