INVESTIGATION ON SHOCK RESISTANCE OF WOOD FROM SECONDARY DAMAGED SPRUCE (PICEA-ABIES [L] KARST) FROM WIND-EXPOSED HIGH-ALTITUDE STANDS IN THE EAST ORE-MOUNTAINS

In this study the influence of secondary changes (slip planes, fungal infection) on the shock resistance of wood from wind-exposed spruces o ut of high altitude stands in the east ore-mountains was investigated. Due to heavy wind exposure of the stands some trees had macroscopic s lip planes und brash fractures which were documented along the stem af ter tree felling and sawing. The impact bending of the wood was examin ed by an instrumented single-blow impact test, which enables the inter pretation of load-time-diagrams for the fracture behavior. Low shock r esistance only occurred in stem zones with pronounced slip planes and brash fractures. These secondary changes in the tree can already be de tected with the naked eye at the bark surface in form of resin exudate s and a callus-like wood formation (''Wulstholz''). In contrary to the se findings wood of the pollution affected trees without secondary cha nges did not respond by a significant decrease in shock resistance. Wo od from highly polluted stands in high altitudes of the east ore-mount ains can be utilized without any limitations if individual trees with the described secondary changes are excluded from further processing.