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In order to determine the most appropriate gap size for improvement of natural regeneration by primary felling of the schelterwod system (preparatory and seed cuttings), 18 gaps of 1-2, 4-5 and 9-11 are (6 replications in each gap size) were selected randomly in northern aspects 1200-1400 m a.s.l., located in regeneration compartments of Seri One, in Shourab forest management plan, Golband district. Depending on their size, some 1m2 micro plats were chosen in these gaps in order to measure the frequency, height and collar diameter of the saplings regenerated after the cutting.
The results showed that with increased gap size, contrary to maple (Acer velutinum), beech (Fagus orienalis Lipsky) frequency decreased. Within the investigated gaps, saplings frequency ranged between 4-9 per m2, mean height between 20-100 cm and collar diameter between 4-6 mm. In gaps of 1-2 are and 4-5 are, height and collar diameter while in gaps of 1-2 are saplings frequency were greater than those in larger gap sizes.
Generally, it can be deduced that regeneration characteristics, from viewpoint of establishment and growth, are more limited in greater gaps (9-11 are) but are benefited by more favorable conditions in smaller gaps (1-2 and 4-5 are), where removal of tree elements is possible as a single tree. In deed, this research recommends that in order to improve natural regeneration, marking area must not exceed 5 are when marking is performed to remove the crown canopy, which is created by primary cuttings of the shelter wood system (preparatory and seed cuttings) and the selection system.