Comparison of tree species diversity in the beech managed (selection cutting) and unmanaged forest stands (Case study: Shastkalateh Forest- Gorgan)

In order to comparison of tree species diversity were located 12 sample plots in 1 ha and 100×100 meters, and diameter at the breast height all of trees measured after registering species in the beech managed and unmanaged forest stands of Shastkalateh forest. Then, species diversity indices average based on basal area was calculated in sample plots and was used independent T-Test for comparison of average difference. In this study, richness indices (Margalef and Menhinick), heterogeneity indices (Simpson, Shannon- wiener) and evenness indices (Simpson, Smith-Wilson, modified Nee, Camargo) were calculated. The results showed that richness indices were significantly greater in managed stands. Average of heterogeneity indices were greater in managed stands and average of evenness indices were greater in unmanaged stands. But there are not significant differences in the 0.05 confidence interval. In general, richness and heterogeneity are more and eveness is less in manaed stands. Simpson, Smith- Wilson and Margalef indices calculated as appropriate indices for evaluate of heterogeneity, evenness and richness indices in the study area. According to the results of this research, single tree cutting is suggested as a appropriate approach for maintain and even increase of species diversity natural stands of north forests because it is follow of natural degradation condition in small scale.