Some metals in aboveground biomass of Scots pine in Lithuania

The stocks of iron (Fe), manganese (Mn), zinc (Zn) and aluminium (Al) in different compartments of the aboveground tree biomass were estimated in Scots pine (Pinus sylvestris L.) stands in Lithuania. Simulated removals of metals due to the forest biomass extraction in a model Scots pine stands during a 100-year-long rotation period were compared with metals pools in sandy soil and the fluxes through atmospheric deposition. Applying whole tree harvesting, total removal comprised about 20 kg ha−1 of each Al and Mn, and 5 times lower amount of each Zn and Fe. The metals were mainly removed with stemwood and living branches. However, metal export with aboveground biomass represented relatively small proportion of metals in mineral sandy soil. The annual inputs of Fe and Zn with atmospheric deposition were over 10 times higher than the mean annual removals with total aboveground biomass. The content of metals in forest biomass fuel ash was relatively small to compare with their total removals. The findings of this study have an important implications for future practice, i.e. the recommended maximum forest biomass fuel ash dose for the compensating fertilising could be increased with respect to balanced output - input in Lithuania.