SHEAR STRENGTH AND ANALYSIS OF SHEAR AREA ON WOOD/BARK INTERFACE ON BEECH WOOD (FAGUS SYLVATICA L.)

摘要

The structure of both cambium and the last-differentiated cells from cambium influence the adhesion of bark on wood. In the submitted paper, the bark/wood adhesion is evaluated by means of measuring the shear strength in longitudinal and tangential direction of the wood/bark interface on woody plant beech (Fagus sylvatica L.) during one year. The growing period and dormant period and moisture of the wood/bark interface proved to be important factors influencing the shear strength. The shear strength measured during the dormant period in the greenstate showed values approximately 100% higher than those measured during the growing period. Considering the 12%-moisture, the values of shear strength proved to be circa 300% higher in comparison to the green state. The shear area during the dormant period was led through the zone of the last-created sieve tubes of non-collapsed late phloem, whereas during the growing period the shear area passed through the cambium zone. The structure of shear areas is also significantly influenced by diverse structure of narrow and wide phloem rays.