Ecosystem Processes and Nitrogen Export in Northern U.S. Watersheds
There is much interest in the relationship of atmospheric nitrogen (N) inputs to ecosystem outputs as an indicator of possible “nitrogen saturation” by human activity. Longer-term, ecosystem-level mass balance studies suggest that the relationship is not clear and that other ecosystem processes may...
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Wiley
2001-01-01
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| Series: | The Scientific World Journal |
| Online Access: | http://dx.doi.org/10.1100/tsw.2001.328 |
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| author | Robert Stottlemyer |
| author_facet | Robert Stottlemyer |
| author_sort | Robert Stottlemyer |
| collection | DOAJ |
| description | There is much interest in the relationship of atmospheric nitrogen (N) inputs to ecosystem outputs as an indicator of possible “nitrogen saturation” by human activity. Longer-term, ecosystem-level mass balance studies suggest that the relationship is not clear and that other ecosystem processes may dominate variation in N outputs. We have been studying small, forested watershed ecosystems in five northern watersheds for periods up to 35 years. Here I summarize the research on ecosystem processes and the N budget. During the past 2 decades, average wet-precipitation N inputs ranged from about 0.1 to 6 kg N ha–1 year–1 among sites. In general, sites with the lowest N inputs had the highest output-to-input ratios. In the Alaska watersheds, streamwater N output exceeded inputs by 70 to 250%. The ratio of mean monthly headwater nitrate (NO3–) concentration to precipitation NO3– concentration declined with increased precipitation concentration. A series of ecosystem processes have been studied and related to N outputs. The most important appear to be seasonal change in hydrologic flowpath, soil freezing, seasonal forest-floor inorganic N pools resulting from over-winter mineralization beneath the snowpack, spatial variation in watershed forest-floor inorganic N pools, the degree to which snowmelt percolates soils, and gross soil N mineralization rates. |
| format | Article |
| id | doaj-art-c1f486d304074bbb994fc05a74ce1a5f |
| institution | Kabale University |
| issn | 1537-744X |
| language | English |
| publishDate | 2001-01-01 |
| publisher | Wiley |
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| series | The Scientific World Journal |
| spelling | doaj-art-c1f486d304074bbb994fc05a74ce1a5f2025-02-03T05:46:23ZengWileyThe Scientific World Journal1537-744X2001-01-01158158810.1100/tsw.2001.328Ecosystem Processes and Nitrogen Export in Northern U.S. WatershedsRobert Stottlemyer0U.S. Geological Survey, Ft. Collins, CO 80526, USAThere is much interest in the relationship of atmospheric nitrogen (N) inputs to ecosystem outputs as an indicator of possible “nitrogen saturation” by human activity. Longer-term, ecosystem-level mass balance studies suggest that the relationship is not clear and that other ecosystem processes may dominate variation in N outputs. We have been studying small, forested watershed ecosystems in five northern watersheds for periods up to 35 years. Here I summarize the research on ecosystem processes and the N budget. During the past 2 decades, average wet-precipitation N inputs ranged from about 0.1 to 6 kg N ha–1 year–1 among sites. In general, sites with the lowest N inputs had the highest output-to-input ratios. In the Alaska watersheds, streamwater N output exceeded inputs by 70 to 250%. The ratio of mean monthly headwater nitrate (NO3–) concentration to precipitation NO3– concentration declined with increased precipitation concentration. A series of ecosystem processes have been studied and related to N outputs. The most important appear to be seasonal change in hydrologic flowpath, soil freezing, seasonal forest-floor inorganic N pools resulting from over-winter mineralization beneath the snowpack, spatial variation in watershed forest-floor inorganic N pools, the degree to which snowmelt percolates soils, and gross soil N mineralization rates.http://dx.doi.org/10.1100/tsw.2001.328 |
| spellingShingle | Robert Stottlemyer Ecosystem Processes and Nitrogen Export in Northern U.S. Watersheds The Scientific World Journal |
| title | Ecosystem Processes and Nitrogen Export in Northern U.S. Watersheds |
| title_full | Ecosystem Processes and Nitrogen Export in Northern U.S. Watersheds |
| title_fullStr | Ecosystem Processes and Nitrogen Export in Northern U.S. Watersheds |
| title_full_unstemmed | Ecosystem Processes and Nitrogen Export in Northern U.S. Watersheds |
| title_short | Ecosystem Processes and Nitrogen Export in Northern U.S. Watersheds |
| title_sort | ecosystem processes and nitrogen export in northern u s watersheds |
| url | http://dx.doi.org/10.1100/tsw.2001.328 |
| work_keys_str_mv | AT robertstottlemyer ecosystemprocessesandnitrogenexportinnorthernuswatersheds |