Azam Rezaie Kivi - Assis. Prof. of Plant Biology, Islamic Azad University, Khalkhal Branch, Khalkhal, Iran.
Farzam Tavankar - Assoc. Prof. of Forest Science, Islamic Azad University, Khalkhal Branch, Khalkhal, Iran.

Wild service is one of the native tree species in the northern forests of Iran. In this research, frequency and growth characteristics of wild service trees were investigated through systematic plot sampling in the mountain mixed beech stands in northern forests of Iran. The results showed that the frequency of the wild service trees was ۶.۶ stem ha-۱ with an average diameter at breast height (DBH) of ۴۵.۴ cm, and an average height of ۱۹.۳ m. The altitude and slope aspect have significant effect on frequency, DBH, height, H/DBH and volume of S. torminalis. The slenderness coefficient of these trees was calculated as ۰.۵۰. Frequency of the wild service trees decreased by increasing altitude, and the highest frequency of this trees was observed in the northern slopes. The average DBH and height of wild service trees were significantly higher in the northwest slopes. Average species importance value (SIV) of wild service trees was obtained ۷.۶, and average Green’s index (GI) for this species was ۰.۰۰۲۲, indicating random distributions in the study area. Results highlighted that the S. torminalis is one of the ecologically valuable tree species in the natural mixed beech Hyrcanian mountain forests. It is important to ensure a regular distribution of wild service tree even with small clusters or single individuals.

Wild service tree, species importance value, slenderness coefficient, Green’s index