Road effect on diameter growth of trees in Caspian forests of Iran

Forest roads are the most important elements of forestry projects, the management, supervision, care, and only access way to the forest for mechanized harvesting and using other services of forests. The aim of this study was to compare the current annual increment of basal area in different distances from the road in northern forests of Iran. For this purpose, 50 plots were established in 5 distance classes (010, 1020, 2030, 3040, and 4050 m) on the 10 perpendicular transects to the forest road. In each plot current annual increment of basal area of 6 trees were measured by trunk core samples. Results of ANOVA test showed that there is no significant difference among the current annual increment of basal area in different distance classes from the roads. The results also showed that with increasing of distance from the roads into forest interior, current annual increment of basal area were reduced. The UNIANOVA test showed that there was a significant difference between interaction distance classes and diameter classes on current annual ring and diameter increment (p= 0.00).