• Login
    View Item 
    •   Home
    • University of Alaska Fairbanks
    • UAF Graduate School
    • Biological Sciences
    • View Item
    •   Home
    • University of Alaska Fairbanks
    • UAF Graduate School
    • Biological Sciences
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of Scholarworks@UACommunitiesPublication DateAuthorsTitlesSubjectsTypeThis CollectionPublication DateAuthorsTitlesSubjectsType

    My Account

    Login

    First Time Submitters, Register Here

    Register

    Statistics

    Display statistics

    Latitudinal patterns of amino acid cycling and plant N uptake among North American forest ecosystems

    • CSV
    • RefMan
    • EndNote
    • BibTex
    • RefWorks
    Thumbnail
    Name:
    McFarlandSignatures.pdf
    Size:
    459.9Kb
    Format:
    PDF
    Description:
    Signature Page
    Download
    Thumbnail
    Name:
    McFarland.doc
    Size:
    1.217Mb
    Format:
    Microsoft Word
    Description:
    Dissertation
    DownloadPDF Variant
    Author
    McFarland, Jack W.
    Chair
    Ruess, Roger
    Committee
    Boone, Richard
    Chapin, Stuart F. III
    Kielland, Knut
    Hendrick, Ronald L.
    Keyword
    organic nitrogen
    forest ecosystems
    Metadata
    Show full item record
    URI
    http://hdl.handle.net/11122/79
    Abstract
    Interest in the role of organic nitrogen (N) to the N economy of forest ecosystems is gaining momentum as ecologists revise the traditional paradigm in N cycling to emphasize the importance of depolymerization of soil organic matter (SOM) in controlling the bioavailability of N in forest soils. Still, there has yet to be a coordinated effort aimed at developing general patterns for soil organic N cycling across ecosystems that vary in climate, SOM quality, plant taxa, or dominant mycorrhizal association: ectomycorrhizae (EM) vs. arbuscular mycorrhizae (AM). In this study, experimental additions of 13C15N-glycine and 15NH4+ were traced in situ through fine root and soil N pools for six North American forest ecosystems in an effort to define patterns of plant and microbial N utilization among divergent forest types. Recovery of 15N in extractable soil pools varied by N form, forest type, and sampling period. At all sites, immobilization by the soil microbial biomass represented the largest short-term (<24 h) biotic sink for NH4+ and amino acid-N, but differences in microbial turnover of the two N forms were linked to cross-ecosystem differences in SOM quality, particularly the availability of labile carbon (C). At the conclusion of the experiment, microbial N turnover had transferred the majority of immobilized 15N to non-extractable soil N pools. By comparison, fine root uptake of NH4+ and glycine-N was low (<10% total tracer recovery), but 15N enrichment of this pool was still increasing at the final sampling period. Since there was no significant loss of 15N tracer within the bulk soil after 14 days for any forest type except sugar maple, it suggests plants have the capacity to capitalize on multiple N turnover events and thus represent an important long-term sink for ecosystem N. Plants in all stands had some capacity to absorb glycine intact, but plant N preference again varied by forest type. Relative uptake of amino acid-N versus inorganic N was lowest in tulip poplar and highest in red pine and balsam poplar, while white oak, sugar maple, and white spruce stands were statistically near unity with respect to the two N forms. However, N uptake ratios were threefold higher in EM-dominated stands than in AM-dominated stands indicating mycorrhizal association in part mediated plant N preference. Thus, amino acids represent an important component of the N economies of a broad spectrum of forest ecosystems, but their relevance to plant nutrition likely varies as a function of microbial demand for C as well as N.
    Description
    Dissertation (Ph.D.) University of Alaska Fairbanks, 2008
    Date
    2008-12
    Type
    Dissertation
    Collections
    Biological Sciences

    entitlement

     
    ABOUT US|HELP|BROWSE|ADVANCED SEARCH

    The University of Alaska Fairbanks is an affirmative action/equal opportunity employer and educational institution and is a part of the University of Alaska system.

    ©UAF 2013 - 2023 | Questions? ua-scholarworks@alaska.edu | Last modified: September 25, 2019

    Open Repository is a service operated by 
    Atmire NV
     

    Export search results

    The export option will allow you to export the current search results of the entered query to a file. Different formats are available for download. To export the items, click on the button corresponding with the preferred download format.

    By default, clicking on the export buttons will result in a download of the allowed maximum amount of items.

    To select a subset of the search results, click "Selective Export" button and make a selection of the items you want to export. The amount of items that can be exported at once is similarly restricted as the full export.

    After making a selection, click one of the export format buttons. The amount of items that will be exported is indicated in the bubble next to export format.