Effects of atmospheric nitrogen deposition on nutrient balances in forest ecosystems

青森市志野河的氮沉降量超过了10千克。然而，没有出现氮饱和的症状。本研究旨在研究大气降水对日本雪松林分氮素动态和其他元素收支的影响。夏季，当风从东南或南风吹来时，由于开放的总体降水造成的氨输入增加。夏季冠层对氮素的吸收增加。这表明日本雪松林分缺乏氮素，因此大气氮沉降可能会增加森林的生长。氮素转化产生的酸度影响土壤剖面中的总酸产生。产生的酸度被阳离子交换和/或风化所消耗。枯枝落叶层的钙离子供应超过了10 cm深度的淋溶。日本雪松针叶中含有大量的钙，有助于钙离子的供应和积累。由此可见，该杉木林土壤酸化严重。此外，枯枝落叶分解速率低时，盐基离子在枯枝落叶层中积累。在分解速率较高的情况下，盐基阳离子在土壤剖面中积累。枯枝落叶层不仅影响盐基阳离子的积累，而且还影响渗水量。枯枝落叶物层的物理性质是估算森林生态系统养分收支的重要指标。

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.