Nutrient distribution and bioaccumulation in silver birch (Betula pendula Roth) biomass grown in nutrient-poor soil

Silver birch growing on extremely nutrient-poor stands of inland dunes was characterized by low contents of these nutrients in its biomass. The nutrient accumulation also depended on its age.

Silver birch (B. pendula) often colonizes inland dunes, as geomorphologically sensitive and unstable environments. Considering its importance in the protection of ecosystems associated with such landforms, we aimed to evaluate the nutrient distribution and bioaccumulation in the organs of that tree. The study covered three stands, aged 12, 20, and 34 years. Ten average trees were sampled from each stand, including fine and coarse roots, stemwood, bark, coarse and fine branches, and leaves along with soil samples at depths of 0–10, 10–20, 20–40, and 40–80 cm. The contents of macro- and micronutrients were analyzed in collected soil and biomass samples. The soils were strongly acidic and very poor in the studied elements. The nutrient distribution in the birch biomass was highly variable. For most of the elements, the highest contents were recorded in leaves. The highest amounts of Fe were found in fine roots, while Mn and Zn were the most abundant in the bark. Wide variability was also apparent in the bioaccumulation factors. These were usually the highest in the leaves or bark and the lowest in the stemwood. Among the studied elements, N was the most bioaccumulated, followed by S, Zn, Cu, Mn, and P. Nutrient distribution in the birch biomass was typical for tree species. Nutrient levels were generally low, however, significantly higher than their concentrations in the soil, indicating a strong bioaccumulation. The relationship between nutrient accumulation and stand age was observed.