THE STOCK AND CONTENT OF MICRONUTRIENTS IN ABOVEGROUND BIOMASS OF SCOTS PINE STANDS OF DIFFERENT DENSITIES

For any plant, the micronutrient content in its tissues is of extreme importance, as both deficiency and excess can be harmful. Most of the nutrient balance studies focus on macronutrients, while micronutrients are usually neglected. The aim of the study was to estimate the impact of a stand density (number of trees per area) on stocks of four micronutrients: copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn) in the aboveground biomass of mature Scots pine (Pinus sylvestris L.) stands of various densities. The nutrient content in dry mass and the stock of nutrients per hectare were assessed. Five sample plots, 0.5 ha each, were established in 82-year-old Scots pine stands of different densities (476-836 trees per ha). The dry mass of all trees on the experimental plots was estimated using allometric equations. The mass of aboveground biomass was calculated as the sum of the following compartments of trees: 1) stems (wood and bark), 2) dead branches, 3) thick branches, 4) thin branches and 5) needles. The content of the elements was determined in separate samples from tree compartments taken for chemical analysis. The content of Cu, Fe and Mn was the highest in needles, while Zn was the richest in the stem bark. The content of the investigated micronutrients decreased in the following order: Mn>Zn>Fe>Cu. Relative concentartions of the four micronutrients in the distinguished tree compartments were similar. No influence of a stand density on the micronutrient stock was found.