Long-term wildfire effect on nutrient distribution in silver birch (Betula pendula Roth) biomass

This study aimed to evaluate the long-term effects of wild fi re on nutrient distribution in a silver birch ( Betula pendula Roth) biomass. Two stands (post- fi re and control) of the same age (27 years) were studied in the Cierpiszewo Forest District (central Poland). The stands were located on Brunic Arenosols developed from aeolian sands. The soil and birches were sampled in 10 replicates per stand. The soil samples were taken from depths of 0–10, 10–20, 20–40 and 20–40 cm using a corer. Samples of fi ne roots, coarse roots, stemwood, stem bark, coarse branches, fi ne branches and leaves were taken from the trees. The basic soil characteristics were determined using standard proce-dures. In addition, the carbon (C), nitrogen (N), sulfur (S), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), copper (Cu) and zinc (Zn) contents were analyzed in the soil and biomass samples. The soils were strongly acidic and poor in the studied elements. The nutrient content in the biomass varied strongly among the organs. The most abundant elemental contents were usually in the leaves, followed by the fi ne roots and fi ne branches or bark. The lowest nutrient contents occurred in the stemwood. Statistically signi fi cant differences were recorded between the post- fi re and control stands for some elements. There were higher P, K and Zn contents in most of the biomass fractions in the post- fi re stand, as well as Mg and Mn in the roots and stemwood. The control stand had mostly higher contents of N and Ca. The effects of fi re on the Fe and Cu accumulations varied among the organs and was not clear for S. Generally, birch showed the highest bioaccumulation intensity for N and the lowest for Fe. Among all the studied nutrients, the bioaccumulation factors were usually the highest in the leaves and the lowest in the stemwood. It can be concluded that fi re is an important factor in in fl uencing nutrient management in silver birch stands, even a few decades after its occurrence.