The Effect of Growth Stresses on the Anatomical and Physical Properties of Fagus orientalis L.

Growth stresses develop in trees' trunks during formation and maturation of their growth rings. The asymmetric of growth stress field causes formation of abnormal wood called "reaction wood". This study has been conducted to characterize the effect of growth stresses on anatomical and physical properties of Fagus orientalis. Longitudinal growth stress was measured at 8 equidistant points on circumference, at breast height of 19 standing Beech trees in parcels 117 and 223/220 at Kheyroudkenar Research Forest. Using displacement gauge, longitudinal Point with greatest stress history on each sample tree was marked, and then trees were cut down to collect test materials for anatomical and physical properties. On cross-section of each sample bolt segment of harvested trees, area with greatest stress and its opposite were identified to cut out specimens. Results of investigations have shown that in the area with greatest values of longitudinal stress, tension wood has formed. In this area comparing with opposite wood of cross-section, number of vessels, diameter of vessels' lumen and typical fiber diameter were lower, but length and wall thickness of fibers and average percent of fiber content, shrinkage and swelling rates were higher. There were no significance statistical difference between moisture content and basic specific gravity in wood of both areas.