Effect of Cultivation Methods on Wood Static Bending Properties in Alnus Glutinosa

This study was carried out to determine radial variation of wood density, modulus of elasticity (MOE), modulus of rupture (MOR) and stress at elastic limit in plantation and natural alder (Alnus glutinosa) forests in north of Iran. Testing samples were taken at breast height of the stem and at three radial positions (10, 50 and 90 % of radius) for both cultivation methods (natural and plantation forests) to determine wood mechanical strength properties according to the ASTM standard. Analysis of variance indicated that cultivation methods (natural and plantation forest), radial position and interaction between planting position and radial direction had no significant effects on the modulus of elasticity (MOE), modulus of rupture (MOR) and stress at elastic limit in alder wood. Only the radial position had a significant effect on the wood density. Wood density was increased along radial direction from the pith to the periphery for both planting conditions. Overall, the mechanical strength properties in plantation forest were slightly higher than in natural forest. The relationship between wood density and mechanical properties were analyzed by linear regression. A positive relationship was found between wood density and mechanical properties for both planting conditions. These relationships were stronger in plantation forest than in natural forest.