Skip to Main Content
Potential canopy interception of nitrogen in the Pacific Northwest, USAAuthor(s): Jeffrey M. Klopatek; Matthew J. Barry; Dale W. Johnson
Source: Forest Ecology and Management, Vol. 234, p. 344-354
Publication Series: Scientific Journal (JRNL)
PDF: View PDF (2.6 MB)
DescriptionNitrogen deposition is increasing worldwide from anthropogenic sources and encroactring upon previously N limited ecosystems. Recent literature reports increases in inorganic N deposition in Pacific Northwest forests of the United States due to expanding urbanization. We examined the contributions of atmospheric deposition of inorganic N to old-growth and second-growth Douglas-fir (Pseudotsuga menziesii) forests in the Cascade Mountains of southern Washington State. We used ion exchange resin lysimeters (IERs) to measure throughfall and compared it to data from a nearby atmospheric deposition recording station. Observed differences led us to install IERs above and throughout the canopy of an old- and second-growth forest stand at the Wind River Canopy Crane Research Facility. Total NH4-N and N03-N deposition was 4.06 and 2.06 kg/ha, respectively, with NH4-N inputs varying seasonally. Canopy interception in the first 5 m of canopy was >80% of N03-N deposition during the winter months. with negative net canopy exchange (NCE) accounting for nearly 90% N03-N input (uptake). NCE for NH4-N during the winter months was negligible. During the summer months, both NH4-N and NO3-N up within the canopy. Contrary to the winter period, nearly all NH4-N entering the canopy was retained. Although the pattern of canopy interception varied according to canopy architecture and age of stand, all species were extremely efficient in reducing the input of inorganic N to the forest floor. Greater deposition in these stands as compared to the nearby NADP site was attributed to higher precipitation. Needle concentrations of N and δ15N showed no differences throughout the canopy profile, in contrast to both C and δ13C that exhibited significant increase from top to the lower levels. Differences in concentrations of C, δ13C, N, and δ15N were noted among the old-growth species.
- You may send email to firstname.lastname@example.org to request a hard copy of this publication.
- (Please specify exactly which publication you are requesting and your mailing address.)
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
CitationKlopatek, Jeffrey M.; Barry, Matthew J.; Johnson, Dale W. 2006. Potential canopy interception of nitrogen in the Pacific Northwest, USA. Forest Ecology and Management, Vol. 234, p. 344-354
KeywordsPseudotsuga menziesii, Tsuga heterophylla, Tsuga plicata, Nitrogen deposition, Pacific Northwest forests, NH4, NO3
- Atmospheric deposition of nitrogen and sulfur and preferential canopy consumption of nitrate in forests of the Pacific Northwest, USA
- Fire-mediated pathways of stand development in Douglas-fir/western hemlock forests of the Pacific Northwest, USA
- Spatial patterns of atmospheric deposition of nitrogen and sulfur using ion-exchange resin collectors in Rocky Mountain National Park, USA
XML: View XML