Effect of Environmental Factors on Natural Regeneration of Beech Stands in the Hyrcanian Forests (Case Study: Kojoor Forest, Namkhaneh District of Kheyroud Forests)

Natural regeneration will guarantee forest future and sustainability. Ecological factors (soil and physiology) may influence regeneration process and provide a variety of sites favorable for seed generation and establishment of different plant species. The present study aimed to evaluate effect of environmental factors on Fagus orientalis regeneration in Kojoor Forest, one of Hyrcanian inscribed sites on UNESCO's Natural World Heritage List.

After determination of high valued and undisturbed stands of F. orientalis Lipeskey on the vegetation map, sampling was carried out with 2.5% of statistical intensity (the surface area of each plot was 0.1ha and statistical network dimension was 200×200m2). The effects of abiotic ecological factors including topography (aspect, elevation, and slope), soil type (pseudoglay, brown forest soil, and brown marmorized), canopy closure (50-70% and >70%) on abundance of regeneration were studied on 60 plots.

The mean density was 0.52seedlings/m2, and Fagus orientalis Lipeskey, and Carpinus betulus fastigiata comprise 82% of seedlings. F. orientalis prefers north faced slopes (Northeast and northern) (probability of 95%; p= 0.044) and the highest seedlings abundance occurs in the elevation of 1,000 to 1,200m a.s.l., while, the altitude of 700 to 800m a.s.l. had the lowest density of seedlings (probability of 95%; p= 0.034). This species more is found on the slope of 0-40% (probability of 95%; p= 0.012) on the pseudoglay and forest brown soil (probability of 99%; p= 0.001). Canopy covers between 50-70% are more suitable for this species and canopy cover >70% had the minimum number of seedlings per hectare (probability of 95%; p= 0.021).

These set of environmental conditions are optimal conditions under which F. orientalis as a climax species of the Hyrcanian Forests will grow and reproduce and Kojoor Forest is a developed old growth forest with the best environmental conditions for establishment and regeneration of climax species like F. orientalis. This site is an undisturbed forest with less anthropogenic effects and diverse topography and soil types which make it the best site of the Hyrcanian Forests.