Skip to content
University of Maryland LibrariesDigital Repository at the University of Maryland
    • Login
    View Item 
    •   DRUM
    • Theses and Dissertations from UMD
    • UMD Theses and Dissertations
    • View Item
    •   DRUM
    • Theses and Dissertations from UMD
    • UMD Theses and Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    INTERACTIONS BETWEEN CHEMICAL, PHYSICAL, AND BIOLOGICAL PROCESSES DURING DESERTIFICATION OF GROUNDWATER-DEPENDENT SEMI-ARID GRASSLANDS

    Thumbnail
    View/Open
    Gardner_umd_0117E_16089.pdf (18.24Mb)
    No. of downloads: 249

    Date
    2015
    Author
    Gardner, Kimberly Vest
    Advisor
    Elmore, Andrew J
    DRUM DOI
    https://doi.org/10.13016/M2SH0Z
    Metadata
    Show full item record
    Abstract
    Desertification is estimated to cost $26 billion per year through loss of agricultural production, water reserves, and air quality. Semi-arid grasslands are prone to desertification through many factors including groundwater pumping. Groundwater pumping below the root-zone of groundwater-dependent vegetation leads to a decrease in vegetation cover exposing bare soil to wind erosion. Desertification of semi-arid grasslands can lead to a permanent change in vegetation state. Identifying when and where ecological changes are irreversible is problematic, requiring observations of a new ecological state that favors the continued process of wind erosion and depletion of soil resources. To determine biological, physical, and chemical processes affecting desertification in semi-arid groundwater-dependent grasslands, I examined hydrological and ecological factors across groundwater-dependent meadows in Owens Valley, California. I developed and compared empirical, process-based, and mechanistic models that predict mass transport. I found that scaled gap size explains 56% of the variation in total horizontal flux (Q), and the process-based model predicts Q better than the mechanistic model indicating the importance of scaled gap size in wind erosion modeling of heterogeneous vegetation. I explored the role of landscape connectivity of bare soil in enhancing Q and quantifying the magnitude of desertification across the landscape using circuit theory and Qrule. I found that landscapes that were more connected than neutral landscapes with the same bare soil cover were associated with groundwater decline during the drought and greater Q. This is consistent with the idea that the enhanced formation of connected pathways is evident at plots that arrived at a particular bare-soil cover via groundwater decline and wind erosion, rather than another process. I analyzed vegetation structure and monitored Q, air quality data, and PM10 emissions to evaluate the relationship between meadow degradation and air quality. I found that management practices have generated a new mid-valley meadow source of PM10 pollution. These results provide information and tools for resource managers of groundwater-dependent semi-arid grasslands to identify areas degraded by wind erosion, producing Q and PM10, and prone to desertification. Managers can use the information and tools to better gauge a well-field's health and adjust the amount pumped from wells.
    URI
    http://hdl.handle.net/1903/16771
    Collections
    • Biology Theses and Dissertations
    • MEES Theses and Dissertations
    • UMD Theses and Dissertations

    DRUM is brought to you by the University of Maryland Libraries
    University of Maryland, College Park, MD 20742-7011 (301)314-1328.
    Please send us your comments.
    Web Accessibility
     

     

    Browse

    All of DRUMCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsThis CollectionBy Issue DateAuthorsTitlesSubjects

    My Account

    LoginRegister
    Pages
    About DRUMAbout Download Statistics

    DRUM is brought to you by the University of Maryland Libraries
    University of Maryland, College Park, MD 20742-7011 (301)314-1328.
    Please send us your comments.
    Web Accessibility