Managed vs. unmanaged Fagus orientalis Lipsky forests: Structure and diversity of natural regeneration in northern Iran

The predominant natural disturbance regime within an old-growth Oriental beech (Fagus orientalis Lipsky) forest has been imitated in order to continue the forest cover. It is unclear how much the silvicultural characteristics of regeneration in a managed forest differ from those in an unmanaged old-growth forest subject only to natural dynamics. In this study, we compared important quantitative (e.g. height, collar diameter, crown width, length of spring shoot on the main stem and length of the uppermost internodes) and qualitative (e.g. healthy, mode of branching and stem form) silvicultural characteristics of beech saplings within the gaps between an unmanaged old-growth Oriental beech compartment and a managed forest in the northern Iran ten years after a single harvest entry using a single-tree selection. Canopy gaps larger than 100 m2 with visible remnants of gapmakers (i.e. stumps) were included in this study. The saplings' characteristics of both compartments were within typical ranges for an old-growth beech forest. Small, but important differences were also observed. The value of beech saplings' density in the managed compartment (4.9 ± 0.7 SE) was significantly (P < 0.05) higher than the unmanaged one (3.4 ± 0.6 SE). Conversely, the value of the Menhinick Richness index in the unmanaged one (0.96 ± 0.05 SE) was significantly (P < 0.01) higher than the managed compartment (0.80 ± 0.04 SE). The sapling spring shoot length in the unmanaged compartment (13.3 ± 1.7 SE) was also significantly (P < 0.01) higher than the managed one (7.3 ± 0.7 SE). Relying on beech trees in a managed compartment will hamper the stability of future forest stands. The imitation of the old growth forest must be complete. To increase the resistance of the forest stands to adverse conditions, pay attention to the tree species richness at the time of marking.