• Login
    View Item 
    •   Home
    • UA Graduate and Undergraduate Research
    • UA Theses and Dissertations
    • Dissertations
    • View Item
    •   Home
    • UA Graduate and Undergraduate Research
    • UA Theses and Dissertations
    • Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of UA Campus RepositoryCommunitiesTitleAuthorsIssue DateSubmit DateSubjectsPublisherJournalThis CollectionTitleAuthorsIssue DateSubmit DateSubjectsPublisherJournal

    My Account

    LoginRegister

    About

    AboutUA Faculty PublicationsUA DissertationsUA Master's ThesesUA Honors ThesesUA PressUA YearbooksUA CatalogsUA Libraries

    Statistics

    Most Popular ItemsStatistics by CountryMost Popular Authors

    Elevated Atmospheric CO2 Impacts Carbon Dynamics in a C4-Sorghum-Soil Agroecosystem---An Application of Stable Carbon Isotopes (d13C) in Tracing the Fate of Carbon in the Atmosphere-Plant-Soil Ecosystem

    • CSV
    • RefMan
    • EndNote
    • BibTex
    • RefWorks
    Thumbnail
    Name:
    azu_etd_1130_sip1_m.pdf
    Size:
    2.656Mb
    Format:
    PDF
    Description:
    azu_etd_1130_sip1_m.pdf
    Download
    Author
    Cheng, Li
    Issue Date
    2005
    Advisor
    Leavitt, Steven W
    Committee Chair
    Leavitt, Steven W
    Walworth, James
    
    Metadata
    Show full item record
    Publisher
    The University of Arizona.
    Rights
    Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
    Abstract
    Although a strong inter-dependence exists between atmospheric carbon dioxide (CO2) and the terrestrial carbon (C) cycle, the response of plant-soil ecosystems to the rapid increase in atmospheric CO2 is not well understood. My dissertation research focused on the impacts of elevated CO2 on the carbon dynamics of plant-soil ecosystems, which were a major part of the overall C4-sorghum Free-Air CO2 Enrichment (FACE) experiment conducted by the University of Arizona and USDA at the Maricopa Agriculture Center, Arizona, USA, in 1998 and 1999. In the experiment, sorghum (Sorghum bicolor (L) Mőench) crop was exposed to elevated CO2 ("FACE": ca. 560 mmol mol-1) and ambient CO2 ("Control": ca. 360 mmol mol-1) interacting with well-watered and water-stressed treatments. The results from my study showed that the seasonal mean soil respiration rate measured in elevated CO2 plots over two growing seasons was 3.3 mmol m-2 s-1, i.e., 12.7% higher than the 2.9 mmol m-2 s-1 in ambient CO2 plots. The increased respiration mainly resulted from the stimulated root respiration under elevated CO2, which increased 36.1% compared to that under ambient CO2. Measured changes in sorghum residue biochemistry caused by CO2 were detected, with decrease of amino acids and hemicellulose carbohydrates by 7% and 8%, respectively, and increase of cellulose carbohydrates and lignin by 49% and 5%, respectively. Phenolics were only significantly higher in FACE roots. The C:N ratio of sorghum tissues was not affected by elevated CO2, but was substantially lower under water stress. The laboratory incubation showed that an average of 7.3% significantly less respired CO2 was released from the FACE-tissue-amended soil than the Control-tissues-amended soil over the full 79-d incubation period. Non-lignin phenolics (r2 = 0.93, p = 0.002), and lignin (r2 = 0.89, p = 0.004) were found to be the most important factors related to the sorghum tissue decomposition. Highly stable residues of FACE sorghum input to the soil resulted in the increase of the recalcitrant C pool and the decrease of the labile C pool. As a result, mean residence time of SOC in FACE field plot increased compared to that in Control plot, suggesting that the SOC under elevated CO2 was more stable against decomposition.
    Type
    text
    Electronic Dissertation
    Degree Name
    PhD
    Degree Level
    doctoral
    Degree Program
    Soil, Water and Environmental Science
    Graduate College
    Degree Grantor
    University of Arizona
    Collections
    Dissertations

    entitlement

     
    The University of Arizona Libraries | 1510 E. University Blvd. | Tucson, AZ 85721-0055
    Tel 520-621-6442 | repository@u.library.arizona.edu
    DSpace software copyright © 2002-2017  DuraSpace
    Quick Guide | Contact Us | Send Feedback
    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.