Effects of strip and single-tree selection methods on woody species diversity in Caspian forests (Iran)

In this study, variations of woody species diversity were investigated in Beech (Fagus orientalis) and Beech-Horn Beam (Carpinus betulus) stands of Janbesara district (located in the west of Guilan province, Iran) after harvesting by single selection method and strip methods. Random-systematic sampling method was applied in the first and last year of the 10-year period and 200×150 network dimensions. Woody species (shrubs and trees in different strata) were recorded in circle shape plots with 1000 m2 for overstory layer and 100 m2 for understory layer. Species richness, Shannon Wiener and Simpson diversity indices were used to evaluate plant diversity in each sampling plot. The means of different diversity indices were calculated and t Test was used to test all indices means differences in both sampling. The results showed that species richness significantly raised and also evenness and plant diversity indices were a little bit increased (but no significant differences) after performing of the single selection approach. Strip harvesting had a significant effect on the species richness as well as all diversity indices of woody species. Our results suggest that single selection approach can be applied as a relevant silvicultural method in Caspian pristine forests for plant diversity conservation accompanied with wood production. But in the destructive forests of this region, more intensive silvicultural methods such as strip method can be applied to make the forests to move towards to potential situation which are more diverse and stable.