Effects of atmospheric nitrogen deposition on nutrient balances in forest ecosystems

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Nitrogen deposition exceeded 10 kg N ha^<-1> yr^<-1> at Shichinohe in Aomori. Nevertheless, there were no symptoms of nitrogen saturation. The aim of this study was to examine the effects of atmospheric deposition on nitrogen dynamics and budget of other elements in Japanese cedar (Cryptomeria japonica) stands.Ammonium input owing to open bulk precipitation increased in summer when wind blew from southeast or south. Uptake of nitrogen in the canopy increased in summer. This suggests that Japanese cedar stands are deficient in nitrogen and atmospheric nitrogen deposition is therefore likely to increase forest growth.Production of acidity due to nitrogen transformation affected on the total acid production in soil profile. Produced acidity was consumed by cation exchange and/or weathering. Calcium ion supply from litter layer exceeded leaching from the depth of 10 cm. Japanese cedar needle contained large amounts of calcium contributed to supply and accumulation of calcium ion. Therefore, it was concluded that serious soil acidification scarely arise in this Japanese cedar stands. In addition, base cations were accumulated in litter layers when litter decomposition rate was low. Incase of high decomposition rate, base cations were accumulated in soil profile. Litter layer affected not only on base cation accumulation, but also on percolated water amounts. Physical properties of litter layer are important to estimate nutrient budget in forest ecosystems.