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Coupled cycling of dissolved organic nitrogen and carbon in a forest stream

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dc.contributor.authorBrookshire, E. N. Jacken
dc.contributor.authorValett, H. M.en
dc.contributor.authorThomas, S. A.en
dc.contributor.authorWebster, Jackson R.en
dc.contributor.departmentBiological Sciencesen
dc.date.accessed2014-03-11en
dc.date.accessioned2014-03-27T13:06:06Zen
dc.date.available2014-03-27T13:06:06Zen
dc.date.issued2005-09en
dc.description.abstractDissolved organic nitrogen (DON) is an abundant but poorly understood pool of N in many ecosystems. We assessed DON cycling in a N-limited headwater forest stream via whole-ecosystem additions of dissolved inorganic nitrogen (DIN) and labile dissolved organic matter (DOM), hydrologic transport and biogeochemical modeling, and laboratory experiments with native sediments. We sampled surface and subsurface waters to understand how interaction among hydrologic exchange, DIN, DON, and dissolved organic carbon (DOC) influence stream N losses at summer baseflow. Added DON was taken up rapidly from the water column at rates exceeding DOC and DIN. A significant fraction of this DON was mineralized and nitrified. Combined DON and NO3-N uptake lengths resulted in spiraling lengths of similar to 210 m, suggesting the potential for multiple. transformations of labile N loads within catchment boundaries. Simultaneous addition of DIN increased DOM uptake, but more so for C, resulting in an upward shift in the C:N ratio of uptake. Sediment incubations also showed a strong biotic influence on DOC and DON dynamics. Despite efficient uptake of added DOM, background DON and high molecular mass DOC concentrations increased downstream, resulting in higher DOM loads than could be accounted for by groundwater discharge and suggesting net release of less bioavailable forms from the channel/hyporheic zone. At the same time, subsurface DOM was characterized by very low C:N ratios and a disproportionately large DON pool despite rapid hydrologic mixing with dilute and high C:N ratio surface waters. Analysis of expected DON loads from conservative hyporheic fluxes indicated that watershed losses of DON would have been seven times greater in the absence of apparent benthic demand, suggesting tight internal cycling of subsurface DON. Our study further demonstrates the potential for significant transformation of N in headwater streams before export to downstream ecosystems.en
dc.description.sponsorshipNSF grant DEB 04-05373en
dc.identifier.citationE. N Jack Brookshire, H. Maurice Valett, Steven A. Thomas, and Jackson R. Webster 2005. COUPLED CYCLING OF DISSOLVED ORGANIC NITROGEN AND CARBON IN A FOREST STREAM. Ecology 86:2487-2496. http://dx.doi.org/10.1890/04-1184en
dc.identifier.doihttps://doi.org/10.1890/04-1184en
dc.identifier.issn0012-9658en
dc.identifier.urihttp://hdl.handle.net/10919/46847en
dc.identifier.urlhttp://www.esajournals.org/doi/pdf/10.1890/04-1184en
dc.language.isoen_USen
dc.publisherEcological Society of Americaen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectcyclingen
dc.subjectdissolved organic carbonen
dc.subjectdissolved organic nitrogenen
dc.subjectforesten
dc.subjectstreamen
dc.subjecthead-water catchmenten
dc.subjecthydrologic lossesen
dc.subjectnutrient uptakeen
dc.subjectspiralingen
dc.subjecttransient storageen
dc.subjectheadwater streamsen
dc.subjectunited-statesen
dc.subjectdynamicsen
dc.subjectnutrienten
dc.subjectecosystemsen
dc.subjectwatershedsen
dc.subjectretentionen
dc.subjectpatternsen
dc.subjecttransporten
dc.titleCoupled cycling of dissolved organic nitrogen and carbon in a forest streamen
dc.title.serialEcologyen
dc.typeArticle - Refereeden

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