• Login
    View Item 
    •   Home
    • UA Graduate and Undergraduate Research
    • UA Theses and Dissertations
    • Master's Theses
    • View Item
    •   Home
    • UA Graduate and Undergraduate Research
    • UA Theses and Dissertations
    • Master's Theses
    • 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

    Delayed Tree Dormancy Resulted in Higher Annual Savanna Gross Primary Productivity in the Northern Sonoran Desert

    • CSV
    • RefMan
    • EndNote
    • BibTex
    • RefWorks
    Thumbnail
    Name:
    azu_etd_19540_sip1_m.pdf
    Size:
    2.188Mb
    Format:
    PDF
    Download
    Author
    Steiner, Blake
    Issue Date
    2022
    Keywords
    Eddy Covariance
    Gross Primary Productivity
    MODIS
    PhenoCam
    Phenology
    Rainfall
    Advisor
    Moore, David J.P.
    
    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, presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
    Abstract
    Drylands support over two billion people and savannas contribute about 25% to global gross primary productivity (GPP). Savannas are water limited ecosystems characterized by two dominant plant functional types: trees and an understory of grass and forbes. It is hard to predict how future changes in water across time and space will affect savanna GPP. This is due to, in part, to trees and understory species having different leaf phenology and rooting depths. By integrating three established models of the carbon-water function of drylands, we developed a general hypothesis that incorporates the phenology and root architecture of the two dominant plant functional types to explain savanna GPP controls. We test the hypothesis that productivity in savanna ecosystems is controlled by the temporal and vertical distribution of soil moisture and differences in leaf phenology growing season length of understory and tree functional types. We used phenology cameras, satellite observations from the MODIS sensors, and an in-situ tower equipped to measure carbon flux by eddy covariance to quantify tree and understory phenometrics, savanna phenometrics, and savanna GPP respectively. To quantify available water resources, we measured rainfall and soil moisture accumulation at two different depths (shallow, < 30 cm | deep, > 30 cm). We found that the leaf phenology of trees and understory plants were distinct from each other and that each plant type was active during periods of different water availability. We found also that the effect of water on GPP varied by season, with GPP being driven most by soil moisture from the summer (R2 > 0.38, shallow & deep), then spring (R2 > 0.23, shallow and deep), and finally the winter (R2 = 0.19, only deep). While the length of the savanna growing season was not related to GPP, delayed leaf senescence tended to increase annual GPP. By comparing the response of leaf phenology in trees and understory to the phenology of the whole ecosystem estimated from satellites, we found that trees showed a similar leaf senescence response to the senescence response of the whole savanna; that the availability of deep soil moisture tended to delay leaf senescence (R2 = 0.96 for trees & R2 > 0.29 for savanna, respectively). In contrast, more shallow soil moisture tended to advance leaf senescence in the understory (R2 > 0.81). These major findings are consistent with our general hypothesis and highlight the important and sometimes compensating effects of rainfall during winter and monsoon seasons. It is likely that any future increase of heavy winter precipitation would assist tree productivity and overall carbon gain in these semi-arid savanna ecosystems.
    Type
    text
    Electronic Thesis
    Degree Name
    M.S.
    Degree Level
    masters
    Degree Program
    Graduate College
    Natural Resources
    Degree Grantor
    University of Arizona
    Collections
    Master's Theses

    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.