Some wood anatomical, physiological, and sylvicultural aspects of Silver fir dieback in Slovenia (NW Yugoslavia)

Silver fir die back in Slovenia (NW Yugoslavia) was evaluated, and growth suppression and some physiological and anatomical aspects of growth ring formation were studied. The drastic growth suppression after 19 50 was reflected in poor basal area increment, and by discontinuous as well as missing rings. Only in the most diseased trees the height increment was affected. Generally latewood percentage and tracheid dimensions remained unchanged. The physiological mechanism of wetwood fom1ation in sapwood of fir is discussed and compared with red heart formation in beech. On the basis of preliminary experiments, osmotic transport is suggested from sapwood to heartwood through the intermediate dry zone. Dieback is significantly correlated with microsite factors such as rockiness and stoniness (r = 0.47*), soil cover continuity (r = 0.55**), and proximity of forest roads (r = 0.43*)