INFLUENCE OF MINERAL ELEMENTS ON WOOD FORMATION OF OLD-GROWTH SPRUCE (PICEA-ABIES [L] KARST)

The influence of mineral element supply on wood formation of old growt h spruce (Picea abies [L.] Karst.) was investigated in relation to oth er exogenous factors, e.g. temperature, precipitation and suction forc e of the soil. At a 110 year-old spruce stand two plots (3300m(2) each ) were selected for studying wood formation, one fertilized in 1986 wi th 98 kg K, 59 kg Ca and 128 kg Mg, the other unfertilized as control. Wood increment, biomass production and mineral element content were i nvestigated for selected trees of each plot. In addition, nutrient ele ments in the cambial region of two trees of each plot were quantified in monthly intervals from May 1991 to March 1992. During the vegetatio n periods 1990 to 1992 the influence of mineral element supply on camb ial activity and cell differentiation was analysed intraannually. The distribution of mineral elements in the cambial region was investigate d also on a subcellular level by Energy-Dispersive-X-Ray analysis (TEM -EDX) parallel to the lignification process studied by UV-spectroscopy . In 1991 the biomass production of the fertilized trees was 30% highe r than those of the controls. Higher K, Ca and Mg contents were regist ered in different tree fractions of the fertilized trees, whereas N co ntents were slightly reduced. The variability of the K and Ca contents in the cambial region was strongly related to ontogenetic factors. Th e fertilized trees showed a significant increase in periclinal cell di visions compared to the controls, which was mainly caused by an extend ed period of cambial activity of the fertilized trees. At the beginnin g of the vegetation period the rate of cell division and the cell dime nsions are strongly influenced by temperature, whereas at a later stag e wood formation is mainly influenced by water availability. In period s with extreme precipitation deficit the positive influence of fertili zation on wood formation was stronger than in periods with high soil w ater content. At the beginning of lignification of the tracheids a str ong decrease of the Ca content in the cell wall layers of the differen tiating cells was observed.