Wood formation in Norway spruce studied by pinning technique and intact tissue sampling method

Seasonal dynamics of xylem formation were studied at a cellular level in Norway spruce (Picea abies) from the lowland forests Sorsko polje (350 m a.s.l.) and the sub-alpine site Pokljuka (1200 m a.s.l.) in Slovenia during the growing season 2003. Th e pinning technique and sampling of intact tissue were performed at weekly intervals to assess the usefulness of both methods for examining wood formation. Pinning induced desiccation of diff differentiated xylem, necrosis of cambial cells and undifferentiated xylem derivatives, and formation of callus, traumatic resin canals and wound-wood. The border between cambial cells and radially expanding cells located inside the callus was a reliable mark for defining the xylem increment reached from the time of wounding. Intact tissue sampling was superior for precise investigations of cambial activity, various developmental stages of tracheids,and for secondary phloem formation