[A-HW27] 流域の水及び物質の輸送と循環－源流域から沿岸域まで－

[AHW27-10] 窒素流入量の異なる森林流域における溶存有機窒素動態

*小林 政広¹、伊藤 優子¹、篠宮 佳樹² (1.独立行政法人森林総合研究所、2.独立行政法人森林総合研究所東北支所)

キーワード：森林, 溶存有機窒素, フラックス, 流出

Increasing atmospheric nitrogen deposition often causes nitrogen saturation in forest ecosystems around Kanto plain in Japan. To clarify the mechanism of nitrogen saturation, we have observed the dissolved nitrogen of bulk precipitation, throughfall, litter leachate, soil water, and stream water in Katsura experimental forest (KEF) with low nitrogen deposition and Tsukuba experimental forest (TEF) with high nitrogen deposition. In the present study, we focused on the flux and discharge of dissolved organic nitrogen (DON) in the studied forest ecosystems. The seasonal variation of the ratio of DON to the total dissolved nitrogen (TDN) was observed for the litter leachate both in KEF and TEF. The DON/TDN ratios for litter leachate, stream water were lower in TEF than in KEF. It may be caused by the high rate of mineralization in TEF with excessive nitrogen.