Appropriate stem number in the first diameter class (N10) for obtaining sustainable stands considering close to nature silviculture(case study: Shamushak forest, Golestan province)

 
Background and objectives: Survey and monitoring of forest areas in which silvicultural interventions were conducted over at least one decade and comparing of quantitative and qualitative characteristics of them with untouched stands could be a useful guide for planning the next interventions considering the goals of close to nature silviculture. Present research was carried out with the aim of studying the natural structure of oriental beech stands with emphasis on stem number in the first diameter class in order to obtain continued stability and adopting an appropriate silvicultural method in accordance with their structure and optimal management by better recognition of them especially surveying number of the trees in first diameter class (n₁₀) as a sign of long-term sustainability of stands and planning for existence of enough numbers of this class in forest areas.
Materials and methods:This study aims to compare the silvicultural characteristics between compartments 127 (managed) and 128 (unmanaged=control) in district one of Jahan-nama water catchment, Gorgan. Five sample plots, each one ha (100 x 100m), were laid out in each compartment, a total of 10ha, in random-systematic network.All of the trees with diameters above 5 centimetres inside the sample plots were harvested using the one hundred percent inventory method. To study the structure and regeneration rate of the stand, transects with a size of 100×10 metres were embedded in the middle of each plot in two directions. The heights of all existing trees in each compartment and other features such as canopy cover and quality of tree trunks were recorded in the related forms. Then, a 3×3 m micro plot was inserted inside each transect in 15m distances in order to study regeneration and the seedlings.
Results:The results showed statistically significant differences of mean diameter and height of trees as well as regeneration number between the two studies compartments. Also, the frequency of stem number in the first diameter class (N₁₀) of the managed compartment was 7 times higher than that of the control compartment. This difference was statistically significant. The results show that the highest difference in diameter classes is less than 15 cm, such that frequency of oriental beech species in the first diameter class (N₁₀) in managed compartment is 4.5 times more than reserve compartment.
Conclusion: Hence, the silvicultural interventions have led the managed stand to uneven-aged structure with sufficient stem number in N₁₀, that with executing of silvicultural tending we could obtain sustainable stands. It will bring continued stability of forest stands with a wide presence of climax species (such as oriental beech) in the long term.