| Nitrogen deposition plays an important role in the structure and function of forest ecosystems,but the redistribution pattern of nitrogen deposition and its components through the forest canopy is not well understood,nitrogen balance in the forest ecosystems still exist uncertainty.In the study,we measured the concentrations of total nitrogen?TN?,dissolved nitrogen?DN?,and particulate nitrogen?PN?fluxes in the four hydrological processes during the growing seasons?from May to October in 2015?in the temperate stands?mixed stands?in the Maroershan region,Northeast China.which includes rainfall outside of the stands,net precipitation?i.e.,throughfall plus stem flow?,the output from the soil layer?surface runoff,subsurface flow,infiltration flow?in the water balance experimental station,and the runoff from the hydrological equilibrium site in the watershed.The objectives were to reveal the input and output processes of nitrogen,its redistribution process,and its influencing factors in the temperate forest ecosystem,in order to quantify and evaluate nitrogen balance in the temperate forest ecosystem.The results showed that:the mean TN depositions from outside of stands,and inside of the mixed stands were 12.65±0.49 and 15.81±0.55 kg N hm-2 a-1,respectively;among which DN and PN account for 83.87%,16.13%,and 67.93%,32.07%of the TN deposition,respectively.The TN deposition of throughfall and stemflow inside the mixed stands were14.86±0.48 and 0.96±0.06 kg N hm-2 a-1,respectively;among which the TN deposition of throughfall accounted of 93.99%of TN inside the mixed stands.The input component of nitrogen deposition was dominated by DN,and the mainly redistributed section of nitrogen deposition was dominated by throughfall in the forest.There was a significant double peak seasonal pattern of TN,DN,and PN fluxes for the mixed stands,in which the deposition fluxes were concentrated in the mid-growing seasons?June—August?.The canopy interception of TN deposition was 3.16±0.9 kg N hm-2 a-1,which PN account for 98.95%of the canopy interception of TN deposition,and these phenomena indicated that the forest canopy significantly enriched the atmospheric nitrogen deposition.The concentrations of TN and DN outside the stands were significantly increased with the rainfall in a negative exponential function?P<0.001?,and significantly increased with the rainfall duration in a negative linear function,and significantly increased with the rainfall interval in a positive linear function.The concentrations of TN and DN in the throughfall of the mixed stands were significantly increased with the throughfall or the throughfall intensity in a negative exponential function?P<0.001?,and significantly increased with the throughfall duration in a negative linear function,and significantly increased with the throughfall interval in a positive linear function.The concentrations of TN and DN in the stem flow of the mixed stands were significantly increased with the stem flow duration in a negative function,and significantly increased with the stem flow interval or the stem flow intensity in a positive linear function.Under the single tree condition,the concentrations of TN and DN in the Betula platyphylla Suk.,Juglans mandshurica Maxim.,Acer mono Maxim.,and Ulmus davidiana Planch.var.japonica?Rehd.?Nakai were significantly increase with the ration of the stem flow bulk to DBH?diameter at breast height?in a log—linear relationship.The output of TN from the soil layer in the water balance experimental station was 3.23kg N hm-2 a-1,among which surface runoff,subsurface flow,and infiltration flow accounted for0.59%,39.11%,60.30%of the TN output,respectively.And surface runoff,subsurface flow,and infiltration flow occurred in the mid-growing seasons?June—August?,among which the nitrogen flux in the subsurface decreased in the earlier stages and increased in the latter stages,while the nitrogen flux in the infiltration flow continuously increased during the mid-growing seasons.When the rainfall exceeds the maximum saturated holding water capacity of the litter layer and the soil layer in the temperate deciduous broad-leaved forest,the concentrations of TN and DN in the surface runoff,subsurface flow,and infiltration flow was higher in the earlier stages than the others period,which due to the scouring and pooling effect of soil water movement.And the concentrations of TN and DN in different soil layer were significantly increased with the rainfall intensity outside the stands in a positive linear function.The litter layer and soil layer interception of nitrogen was 12.58±0.55 kg N hm-2 a-1,which account for19.57%of the TN deposition inside the mixed stands.These phenomena indicated that the input of nitrogen from atmosphere and forest vegetation is mostly retained into forest soil subsystems,and its can absorbed for plant growth and microbial activity.The output of nitrogen from the hydrological equilibrium site in the watershed was 3.03kg N hm-2 a-1,among which DN and PN accounted for 81.49%and 18.52%of the TN output from the hydrological equilibrium site in the watershed,respectively.The maximum monthly output of DN from the watershed occurred in May,and the trend was decreasing from May to November,which related to snow can retain lots of atmospheric nitrogen,the positive feedback mechanism of early spring snowmelt process and the freeze-thaw process in the soil layer.The output concentrations of TN and DN from the hydrological equilibrium site in the watershed were significantly increased with the water level or instantaneous flow in a positive exponential function,and significantly increased with the maximum hydrological temperature in a single peak Gaussian distribution function.The net output of TN from the hydrological equilibrium site in the watershed was 12.78±0.55 kg N hm-2 a-1,this study indicated that the temperate deciduous broad-leaved forest ecosystem in the area plays the role of"nitrogen sink". 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