Fate of nitrogen in riparian forest soils and trees : an N-15 tracer study simulating salmon decay


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dc.contributor.author Drake, Deanne C.
dc.contributor.author Naiman, Robert J.
dc.contributor.author Bechtold, J. Scott
dc.date.accessioned 2006-06-16T18:14:15Z
dc.date.available 2006-06-16T18:14:15Z
dc.date.issued 2005-05-23
dc.identifier.uri http://hdl.handle.net/1912/1015
dc.description Author Posting. © The Authors, 2005. This is the author's version of the work. It is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecology 87 (2006): 1256–1266, doi:10.1890/0012-9658(2006)87[1256:FONIRF]2.0.CO;2. en
dc.description.abstract We introduced a 15N-NH4+ tracer to the riparian forest of a salmon-bearing stream (Kennedy Creek, Washington, USA) to quantify the cycling and fate of a late-season pulse of salmon-N, and, ultimately, mechanisms regulating potential links between salmon abundance and tree growth. The 15N tracer simulated deposition of 7.25 kg of salmon (fresh) to 4, 50-m2 plots. We added NH4+ (the initial product of salmon carcass decay) and other important nutrients provided by carcasses (P, S, K, Mg, Ca) to soils in late October 2003, coincident with local salmon spawning. We followed the 15N tracer through soil and tree pools for one year. Biological uptake of the 15N tracer occurred quickly; 64% of the 15N tracer was bound in soil microbiota within 14 days, and roots of the dominant riparian tree, western redcedar (Thuja plicata), began to take up 15N tracer within 7 days. Root uptake continued through the winter. The 15N tracer content of soil organic matter reached a maximum of ~52%, 5 weeks after the application, and a relative equilibrium of ~40% within 5 months. Six months after the addition, in spring 2004, at least 37% of the 15N tracer was found in tree tissues: ~23% in foliage, ~11% in roots and ~3% in stems. Within the stems, xylem and phloem sap contained ~96% of the tracer N, and ~4% was in structural xylem N. After one year, at least 28% of the 15N tracer was still found in trees, and loss from the plots was only ~20%. The large portion of tracer N taken up in the fall and reallocated to leaves and stems the following spring provides mechanistic evidence for a 1-year lagged tree-growth response to salmon nutrients. Salmon nutrients have been deposited in the Kennedy Creek system each fall for centuries, but the system shows no evidence of nutrient saturation. Rates of N uptake and retention are a function of site history, disturbance, and may also be the result of a legacy effect, in which annual salmon nutrient addition may lead to increased efficiency of nutrient uptake and use. en
dc.description.sponsorship Funding was provided by the Hall-Ammerer Foundation, the Pacific Northwest Research Station of the US Forest Service, the University of Washington Sea Grant Program, and the National Science Foundation (DEB 98-06575). en
dc.format.extent 50688 bytes
dc.format.extent 356994 bytes
dc.format.mimetype application/msword
dc.format.mimetype application/pdf
dc.language.iso en_US en
dc.relation.uri http://dx.doi.org/10.1890/0012-9658(2006)87[1256:FONIRF]2.0.CO;2
dc.subject Ecophysiology en
dc.subject N-15 tracer en
dc.subject Nitrogen en
dc.subject Nitrogen uptake en
dc.subject Oncorhynchus en
dc.subject Riparian en
dc.subject Riparian trees en
dc.subject Salmon-derived nutrients en
dc.subject Soils en
dc.title Fate of nitrogen in riparian forest soils and trees : an N-15 tracer study simulating salmon decay en
dc.title.alternative Fate of nitrogen in salmon-influenced riparian forest soils and vegation : a N-15 tracer study en
dc.type Preprint en

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