Full Length Research Paper

Investigation of the structure and distribution diameter classes models in beech forests of Northern Iran

Ali Reza Eslami¹*, Bahman Karimi², Hamid Payam³ and Ome Kolsoom Derakhshan⁴

¹ Department of Forestry, Rasht Branch, Islamic Azad University, Rasht, Iran.

²Forests and Rangelands Organization, Iran.

³Department of Forestry, Lahijan Branch, Islamic Azad University, Lahijan, Iran.

⁴Young Researchers Club, Rasht Branch, Islamic Azad University, Rasht, Iran.

*Corresponding author. E-mail: dr_eslami2006@yahoo.com. Tel: +98-131-8849456. Fax: +98-131-8849456.

Accepted 18^th April, 2011

 Abstract

The study of natural stands structures and investigation of the utilization facility from probable theories can be a suitable instrument for future natural stands planning. Anyway, the present study was conducted at beech stands of uneven-aged from the southern aspect of Dorfak at a height of 1200 m of sea level in number 21 of the watershed basin, Guilan province. Four sample plots with 1 ha of dimensions’ 100*100 were chosen in four aspects of the region (northern, southern, western and eastern). Inventory of trees was taken with an upper diameter of 7.5 cm as 100%. Then necessary measurements were done by drawing the horizontal and vertical profile on the tape with dimensions’ 100*100 in the eastern north side of each plot. Based on analysis of the obtained data, the estimated frequencies calculated from the result of different statistical distributions were considered by CHI-Square test. The results showed that between different statistical models, the calculated Beta model created good fitting with the frequency diagram for three (southern, western and eastern aspects) of the four studied aspects. As such, the fact that today Meyer Model is used as a pattern to guide the stand by the selection system method, which in most cases does not accommodate the study’s forest sites, should be taken into consideration. In the site of the study (the southern aspect stands), the Beta model can be used to guide and manage the natural stands.

Key words: Guilan beech, south aspect, statistical distributions, beta model.