Žaltauskaitė, J. and  Juknys, R. 2011. Comparison of principal ion fluxes and their modifications in the forest stands of different tree species. Baltic Forestry 17(2): 179-188

Bulk and throughfall deposition under the canopy of the three most common Eastern Baltic region tree species – Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst.) and silver birch (Betula pendula Roth) stands were investigated. The main aim of this study was to assess the effect of tree species on the composition of throughfall fluxes. The highest throughfall enrichment in anions (SO₄^2-, NO₃^-, Cl^-), was detected in the case of the largest canopy surface area (Norway spruce), and the smallest in the case of the lowest canopy surface area (silver birch), indicating that the enrichment is mostly linked to the wash-off of dry deposited anions accumulated on the canopy surface. The birch canopy retained higher amounts of inorganic nitrogen compounds (especially ammonium), and lost more base cations than the coniferous canopies. In particular, the highest leaching of K⁺ was observed in the birch stand, for which K⁺ fluxes under birch canopies were 1.6 and 2.1 times higher than in the spruce and the pine stand, respectively. The most intense ion exchange with ammonium and hydrogen is considered as the main reason of higher potassium leaching from birch foliage.

Key words: bulk deposition, dry deposition, leaching, throughfall, tree species, uptake.