Studying the plants species diversity under microtopography in mixed beech forests, case study: Deldareh forests, Nowshahr

The uprooting of large trees leads to the formation of depressions in the root area and plate-like features next to it, which are referred to as pit and mound microtopography. For studying the plant species diversity in these positions, Deldareh forests, Nowshahr was selected. For this purpose, all pits and mounds were identified in 70 ha of the study area. The presence and frequency of plant species were recorded on these positions and each pit and mound was compared with a plot 2×4m located 25m far from these positions. Firs, to analyze the plant species, biodiversity indices were computed. Then, to study SIV in each position, relative frequency, relative density, and relative dominance were also calculated. The results indicated all indices of diversity and richness had significant difference between positions, except the Simpson one. Accordingly, in the comparison between the pit and control positions, the control position, and between the control and mound positions, the mound position had higher values of the indices. Also, neither of both evenness indices showed a significant difference between different positions. The study of the SIV also showed that in all positions, there is a normal logarithmic curve. The findings of the present study show the high ability of pit and mound effects on increasing the species richness in forest stands. Therefore, the design of silviculture methods should be such that by maintaining and increasing the thickn trees, a certain number of pit and mound microtopography remains per unit area.