Role of stormflow in reducing N retention in a suburban forested watershed, western Japan

Chiwa, Masaaki; Maruno, Ryoko; Ide, Jun’ichiro; Miyano, Takeaki; Higashi, Nobuyuki; Otsuki, Kyoichi

doi:10.1029/2009jg000944

Cited by 26 publications

(15 citation statements)

References 97 publications

(156 reference statements)

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“…Elevated levels of atmospheric N deposition have been reported in the urban and suburban areas of the Fukuoka metropolitan area (Fig. 1b) located near the YEW (Chiwa et al, 2010b, 2012). Elevated atmospheric N deposition due to long‐range transport of nitrogenous pollutants from the east Asian continent has also been reported (Morino et al, 2011; Chiwa et al, 2012; Chiwa et al, 2013).…”

Section: Discussionmentioning

confidence: 92%

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A Nitrogen-Saturated Plantation of Cryptomeria japonica and Chamaecyparis obtusa in Japan Is a Large Nonpoint Nitrogen Source

et al. 2015

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Japanese cedar (Cryptomeria japonica) and Japanese cypress (Chamaecyparis obtusa) plantations account for approximately 30% of the total forested area in Japan. Both are arbuscular mycorrhizal trees that leach more NO 3 -in response to nitrogen (N) deposition than do forests of ectomycorrhizal trees. However, little information is available about the size of N exports from these plantations. The aim of this study was to evaluate nonpoint source N exports from a N-saturated plantation. We collected stream water samples in base-flow (25 samples) and storm-flow conditions (20 events) in a watershed (2.98 ha) where Japanese cypress and Japanese cedar were planted in 1969 (41 yr old). The annual NO 3 -export was calculated from load-discharge relationships. Atmospheric N deposition was also determined. The stream water contained high ) could explain the N saturation. There were only small variations in NO 3 -concentrations in stream water in response to discharge volume, because of the N saturation of the forest ecosystem. Consequently, there were only small errors in estimating annual NO 3 -exports from the studied watershed. The annual NO 3 -export was high (36.1 kg N ha -1 yr -1 ), comparable to values reported for agricultural and urbanized areas. These results suggest that N-saturated forest plantations can become important nonpoint N sources. Our results also suggest that N exports from forest plantations across Japan should be quantified to evaluate nonpoint source N accurately.

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Section: Discussionmentioning

confidence: 92%

“…However, it remains unclear why the annual exportation of NO 3 − was higher than N deposition. Bulk precipitation often considerably underestimates dry deposition (Lindberg et al, 1986; Chiwa et al, 2010b). Therefore, dry deposition should be measured to evaluate precise N budgets in a future study.…”

Section: Discussionmentioning

confidence: 99%

A Nitrogen-Saturated Plantation of Cryptomeria japonica and Chamaecyparis obtusa in Japan Is a Large Nonpoint Nitrogen Source

et al. 2015

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“…All statistical analyses were carried out using an open source statistical programing language of R Version 3.3.3. in urban-or suburban-forested watersheds compared with rural-forested watersheds [10,25,26], and regional-scale spatial patterns of higher atmospheric N deposition were observed in urbanor suburban-forested areas [27][28][29]. In a previous study, river basins included suburban forests, and atmospheric N deposition was moderately high (16 kg N ha −1 year −1 in these areas [30]), which is above the threshold value that could potentially cause N leaching from a forested watershed. Therefore, in the present study, upland forests in the river basins were influential NPSs of N for downstream areas.…”

Section: Discussionmentioning

confidence: 99%

Differences in Stream Water Nitrate Concentrations between a Nitrogen-Saturated Upland Forest and a Downstream Mixed Land Use River Basin

et al. 2017

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Nitrogen (N) saturation of upland forests has been assumed to be a substantial N source downstream. However, removal processes of N, including assimilation and denitrification in the downstream area, have not been clarified. To evaluate the N removal processes, nitrate and organic N concentrations, as well as nitrogen isotope ratio (δ 15 N) and oxygen isotope ratio (δ 18 O) of NO 3 − were measured along three rivers of Tatara River Basin, Japan where upland forests have already been N-saturated. Geographic information system (GIS) based topographical analysis was also conducted to evaluate the land use as urban area in relation to topography. In two of the three rivers, NO 3 − concentrations did not increase from upstream to downstream, despite the potential non-point N sources of urban areas. In another river, NO 3 − concentrations rather decreased.The values of δ 15 N and δ 18 O of NO 3 − and organic N concentrations suggested the presence of denitrification and assimilation over N pollutants in the river whose watersheds have a lower percentage of urban area. The lower percentage of urban area could be explained by the lower topographic index. This study concluded that the NO 3 − leaching from upland N-saturated forests was substantially assimilated or denitrified in the downstream area.

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“…In support of this view, low concentrations of NO 3 in stream water from 100% forested areas were observed (Figure 4). Chronic high atmospheric N deposition generally causes N saturation in forested ecosystems, resulting in high NO 3 concentrations in stream water from forested watersheds (Dise and Wright, 1995;Aber et al, 1998; Chiwa et al, 2010;Chiwa et al, 2012). Such high N leaching causes N eutrophication downstream (Chiwa et al, 2012).…”

Section: Effects Of Agricultural Activities On Atmospheric N and P Dementioning

confidence: 99%

“…Many studies, however, have indicated that high atmospheric N deposition may cause N saturation in forested ecosystems, resulting in high NO 3 À concentrations in stream water from forested watersheds (Dise and Wright, 1995;Aber et al, 1998;Chiwa et al, 2010;Chiwa et al, 2012). Agricultural activities can increase atmospheric N deposition in nearby forests because of high ammonia (NH 3 ) emissions originating from livestock and fertilizer (Boxman et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Assessing the role of forests in mitigating eutrophication downstream of pasture during spring snowmelt

et al. 2014

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Abstract:Little research has examined whether forests reduce stream water eutrophication in agricultural areas during spring snowmelt periods. This study evaluated the role of forests in ameliorating deteriorated stream water quality in agricultural areas, including pasture, during snowmelt periods. Temporal variation in stream water quality at a mixed land-use basin (565 ha: pasture 13%, forestry 87%), northern Japan, was monitored for 7 years. Synoptic stream water sampling was also conducted at 16 sites across a wide range of forest and agricultural areas in a basin (18.3 km 2 ) in spring, summer and fall. Atmospheric nitrogen (N) and phosphorus (P) deposition were measured for 4 years. The results showed that concentration pulses of nitrate, organic N and total P in stream water were observed when discharge increased during spring snowmelt. Their concentrations were high when silicate concentrations were low, suggesting surface water exported from pasture largely contributed to stream water pollution during snowmelt. Atmospheric N and P deposition (4.1 kg N ha À1 y À1 ; 0.09 kg P ha À1 y À1, respectively) was too low to affect the background concentrations of N and P in streams from forested areas. Reduction of eutrophication caused by nutrients from pasture was mainly due to dilution by water containing low concentrations of N and P exported from forested areas, whereas instream reduction was not a dominant process. Results indicate that forests have a limited capacity to reduce the concentration pulses of N and P in stream water during snowmelt in this study basin.

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Role of stormflow in reducing N retention in a suburban forested watershed, western Japan

Cited by 26 publications

References 97 publications

A Nitrogen-Saturated Plantation of Cryptomeria japonica and Chamaecyparis obtusa in Japan Is a Large Nonpoint Nitrogen Source

A Nitrogen-Saturated Plantation of Cryptomeria japonica and Chamaecyparis obtusa in Japan Is a Large Nonpoint Nitrogen Source

Differences in Stream Water Nitrate Concentrations between a Nitrogen-Saturated Upland Forest and a Downstream Mixed Land Use River Basin

Assessing the role of forests in mitigating eutrophication downstream of pasture during spring snowmelt

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