Growth models using to simulate and investigate different forest management methods (Case study: Gorazbon District in Kheyroud Forest, North of Iran)

Hyrcanian forests are the most valuable forests in the north of Iran and industrial harvesting occurs only in this area. It is a productive region near the southern coast of Caspian Sea. In these forests mixed beech stands mostly shown uneven-aged structure that is managed under selection system. In order to determine the priority of uneven aged method not only from an ecological view, but also from other views, especially in economical view compared to other methods, should be prove this important by tools or methods. The growth models enable the simulation of stand development in alternative management schedules and select finally the best method. Nowadays sivicultural tendency has been applied here. 768.4 ha unmanaged forest of Gorazbon district in Kheyroud educational-experimental forest was studied using 258 permanent sample plots. The models were used to optimize the stand structure and the alternatives in which various initial stands should be converted to the optimal uneven-aged structure. The model set consists of individual-tree diameter increment model, individual tree height model, survival model, and a model for ingrowth. The models indicate that the annual volume increment of the forests ranges from 2.5 to 7 m3ha-1a-1 in uneven-aged management, depending on species composition. The models and analysis of this study indicate that the uneven aged forest is more practical and superior than other methods (young even-aged stand, mature even-aged stand, and two-storied stand) in forest conversation and economically wood production.