Wood properties of heavily pollution-damaged spruce (Picea abies [L] Karst) in the high-altitude zones of the eastern parts of Erz Gebirge

The question for the wood properties of the tree species in regard to its further worthiness of cultivation and silvicultural treatment has been raised within the framework of the joint project ''Investigations of Forest-Ecosystems in Erz Gebirge as a basis of a Forest Reconstruction by Ecological Criteria'' undertaken within the framework of the Bundesministerium fur Bildung, Wissenschaft, Forschung und Technologie (BMBF) (Federal Ministry of Education, Research, and Technology). A decrease of tracheid lengths as well as of the lumina of early wood has been ascertained in sapwood annual rings smaller than 0.5 mm in width of mature spruce, the wood of which having been subject to heavy damage due to SO2 pollution. The late wood was characterized by decreasing cell wall thickness and larger microfibril angles within the cell wall layer S-2. The anatomical and structural features of wood distinguished by narrow annual rings have been found both in heavily pollution-damaged trees as well as in trees with comparably narrow annual rings of non-polluted sites. Strength investigations in terms of materials testing according to DIN yielded normal strength values of wood that was not affected by secondary agents. Investigations on particularly small test specimens (Dynstat examinations) up to a minimal annual ring width confirm the known relationships between wood density and impact bending strength. Thus, the wood of spruces growing in the high-altitude belts of the eastern parts of Erz Gebirge may be used without reservations.