Few studies have reported the estimation of nitrogen (N) deposition, including dissolved organic N (DON) fluxes, through water flows and the contribution of snowfall in Asia. In this study, the concentrations and fluxes of DON and dissolved inorganic N (DIN) in bulk precipitation (BP), the throughfall (TF) of trees and understory dwarf bamboo, and stemflow (SF) were evaluated in a cool-temperate forest over three years to clarify N fluxes via precipitation and responses of trees and understory canopies to N deposition. The input of N to the study site in BP was 11.1 ± 1.71 kg N ha-1 year-1, with a significant contribution from DON (78%). Snowfall fluxes contributed up to 46% of the totalNinput, with variations related to the amount of snowfall (2.08-5.52 kgNha-1 year-1). The forest canopy enriched DON (2.11 ± 0.42 kg N ha-1 year-1) but consumed NO3 + NO2-N (-0.73 ± 0.19 kg N ha-1 year-1). In contrast, through the understory bamboo canopy, DON (-1.02 ± 0.55 kg N ha-1 year-1) decreased while DIN (0.35 ± 0.44 kg N ha-1 year-1) increased. This study indicates that DON and snowfall should not be neglected when evaluating total N deposition into forest ecosystems, especially in remote regions. The canopy processes related to the dissolved N in the presence of understory plants might have significant implications for the internal N cycle in forest ecosystems.
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