Single-tree selection system effects on forest soil macrofauna biodiversity in mixed oriental beech stands

Hyrcanian temperate forests are of importance due to their genetic variation, biodiversity, commercial productions and many other ecosystem services. Over the past decades the selection silvicultural system (mostly single-tree selection) has been the dominant method to manage and utilize these forest ecosystems. This study aimed to assess the effect of single-tree selection silvicultural system on mixed beech stands of eastern Hyrcanian temperate forests using soil macrofauna as bioindicator. Therefore 91 forest treefall gaps have been selected of which 36 gaps were natural gaps in managed stands, 41 gaps were human created gaps and 14 gaps were natural gaps in virgin stands. In each gap 3 soil profiles and in each profile 3 soil samples were taken at 3 depths, including litter layer, shallow (0-10 cm) and deep (10-20 cm) soil. Macrofauna of all soil samples were extracted and identified to class level and weighed. Diversity (Shannon and Simpson) and evenness indices were calculated for all soil samples. Results showed that most important macrofauna based on biomass were Clitellata, Gastropoda, Chilopoda and Diplopoda in the study area. In the litter layer of all gaps Gastropoda (snails) have the most amount of biomass followed by Chilopoda (millipedes), while in shallow and deep soil Clitellata (earthworms) and Chilopoda were the main classes based on biomass. There was no significant difference in diversity and evenness indices among the three gap groups (virgin, natural and artificial) which indicates that the single-tree selection system has not intensive and irrecoverable effects on the soil macrofauna of the studied forest stands after about 10 years.