EFFECT OF FERTILIZATION AND LIMING ON THE BIOMASS AND ELEMENT CONTENT IN A MATURE NORWAY SPRUCE STAND (PICEA-ABIES L KARST)

Biomass and mineral content were evaluated in a spruce stand in the French Ardennes. The effect of nitrogen fertilization and liming with carbonate or slag was studied. The stand is a 60-year-old Norway spruce plantation on a poor and acidic soil, with a pH of around 4 in the semi-organic horizons. Symptoms of yellowing and needle loss are present in the control plot and aggravated by the nitrogen treatment. Eight trees in each treatment were sampled 8 years after fertilization as shown in figure 1. Figure 2 shows, for the top 10 verticils, the change in the element concentration distribution related to the position along the stem and to the treatments. The mean values of the concentration and the variance analysis are presented in table I by a group of treatments due to the fact that the nitrogen treatment is not highly different from the control, but the limed treatments (carbonate or slag) are significantly different from the group control + nitrogen fertilization. Figure 4, which depicts the results of the principal component analysis, shows the separation between the groups of limed and unlimed plots, especially in the youngest parts of the tree which have grown since the fertilization was applied (in the needles of the higher branches). The quantitative determination of the dry matter and amounts of elements has been carried out using model of regression with the DBH (C130) as the explicative variable. Table III provides some examples of the relations. These relationships applied to the tree inventory give us the values of the biomass and the element content, as summarised in table IV. The group of limed treatments is different from that of unlimed plots. Figure 4 shows the effects of the treatments for the dry matter (DM) and total mineral content in the different parts of the tree. On this site which is poor in calcium and magnesium the addition of calcium improves the health of the trees both directly and indirectly.