The relationship between plant diversity and above-ground biomass changes in Fagus orientalis L. forests (Case study: Hajikola-Tirankoli, Sari)

The North forests of Iran play a major role in carbon storage through above-ground biomass, and they are of extreme significance in terms of biodiversity. Therefore, the present study was accomplished in order to specify the relationship between species diversity changes and above-ground biomass in the mixed-beech forests in Sari region, Mazandaran Province, Iran. In order to determine the amount of above-ground biomass, some discs of 2 cm thickness were sampled in return for each felled tree at 2-5 m. The samples were put in the oven for 24 hours (105°C) in order to determine their dry density. In order to determine the tree biomass (volume multiplied by dry wood density) and plant diversity (Shannon- Wiener's diversity, richness and evenness indices), a network with grid dimensions of 80 × 100 m was laid on the topographic map and totally 50 400 m2 sampling plots were established in the study area in an area about 46.4 hectare. For collecting data related to herbaceous cover, a micro sampling plot was established in the center and four other micro plots with the same dimensions were dismounted in each corner of plot. To measure the biomass of litters within plot, micro plots of 50 × 50 cm2 were established. Herbaceous cover and litters were weighted immediately after collecting in the field and were dried in an oven at a temperature of 65°C. The results indicated that tree biomass values, herbaceous and litters were 379/11, 0/213 and 7/65 tons per hectare, respectively. Findings of this investigation indicated that there was no significant relationship between tree layer biomass values, herbaceous and litters with diversity indicators. The results show that we cannot take advantage of biodiversity indicators for proper forest management for correct monitoring the biomass in the study area.