Preliminary results of survey on stand structure in permanent research plots of Hyrcanian intact beech (Fagus orientalis Lipsky) forests

Having knowledge on stand structure and application of appropriate silvicultural interventions based on ecosystem approach and close to nature forest management is essential for sustainability of forest. This research started from 2009 in intact oriental beech (Fagus orientalis Lipsky) stands in four regions of the Hyrcanian forests. Twelve sample plots, each one ha, have been established in three development stages of initial, optimal and decay and 100% survey has been applied within the plots. A transect of 1000 m2 has been laid out on the middle of the plot and diameter at breast height, tree height and coordination have been registered. Vertical and horizontal structure and the stand structure have been illustrated by SVS software and structure triangle. Results indicated that stem number varied between 188 in the decay and 475 ha-1 in the initial stages. Number of deadwood varied between 7 and 30 ha-1, among them 3 mature deadwoods with diameter more than 60cm. Mean basal area, total volume and deadwood volume was calculated to 40.65 m2ha-1, 592.6 and 55.8 m3ha-1, respectively. The stands in the optimal stage showed two layers while the other stages were three storied stands. The high proportion of volume in large and extra-large timbers indicated that the studied intact stands were old growth and the structure was far from the theoretical irregular structure. Hence, different silivicultural interventions could be introduced in different development stages.