عنوان مقاله [English]
In order to determine the most suitable spacing of ash, (Fraxinus excelsior L.), the effect of three levels of planting spaces ( 1.5×1.5, 2×2 and 2.5×2.5 meters) on quantitative and qualitative characteristics of ash were examined. Statistical design used was random completely block design with three replicates. The site is located in north- west aspect, 250 m a.s.l and 5 percent slope in south of Sari in Mazandaran province. After termination of ten years period, survival, height, diameters and some quality traits of trees were measured and recorded. The results showed that the effect of planting space on tree survival (p<0.05), tree collar diameter and diameter at breast height and volume per hectare (p<0.01) were significant. But the difference between treatments was not significant in tree height. The lowest percentage of survival was related to spacing of 1.5×1.5 meters interval of trees and there was no significant difference between two other treatments. Mean diameters of trees were 2.75, 3.56 and 3.81 centimeters and related to 1.5×1.5, 2×2 and 2.5×2.5 meters spacing of treatment, respectively. The mean volume per hectares increased with decreasing of planting space. The effect of planting space on h/d was significant (p<0.01). But the percentage of forking was not significantly affected by planting space. Maximum rate of h/d and minimum percentage of forking were seen in space of 1.5×1.5 meters.