Effects of the spatial heterogeneity formed by <i>Ambrosia dumosa</i> on individual and population growth of the invasive grass <i>Schismus barbatus</i>
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The Ohio State University / OhioLINK
2009
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ndltd-OhioLink-oai-etd.ohiolink.edu-osu12332643112021-08-03T05:55:05Z Effects of the spatial heterogeneity formed by <i>Ambrosia dumosa</i> on individual and population growth of the invasive grass <i>Schismus barbatus</i> Rodriguez-Buritica, Susana Ecology Invasive species demography spatial heterogeneity Islands of fertility <i>Schismus barbatus</i> <i>Ambrosia dumosa</i> Desert ecology Natural ecosystems are exposed to numerous factors that determine their structure and dynamics. Although change is typically inherent in to biological systems, very few factors change a natural ecosystem as drastically as the arrival and successful establishment of non-native species. The impact of the Mediterranean grass (<i>Schismus barbatus</i>) in the southwestern U.S. exemplifies such dynamics. In my dissertation, I empirically and theoretically explore two components of <i>Schismus</i> invasion. First, native shrubs may promote <i>Schismus</i> invasion if <i>Schismus</i> benefits from the favorable growth conditions that shrubs provide. Second, <i>Schismus</i> may threaten ecosystem level properties if <i>Schismus</i> precludes establishment of shrubs. Thus <i>Schismus</i> may compromise the maintenance of Islands of fertility that favor growth of native plant community. To meet these objectives, I explore <i>Schismus</i> performance with respect to the location and size of one of the most abundant native shrubs in the Sonoran and Mojave Deserts, the Bur-sage shrub, <i>Ambrosia dumosa</i>. As a first approximation to the study system, I describe the natural distribution of <i>Schismus</i> with respect to the location of native shrubs (Chapter 1). Then, I examine factors that control <i>Schismus-Ambrosia</i> interaction using a three-year field experiment (Chapter 2), and subsequent characterization of soil nutrients changes around <i>Ambrosia</i> shrubs in the context of <i>Schismus</i> invasion (Chapter 3). I found that <i>Schismus barbatus</i> responds to the spatial heterogeneity formed by <i>Ambrosia</i>. This response is strongly controlled by water availability (Chapters 1 and 2). <i>Ambrosia</i> creates a dichotomous landscape formed by nutrient rich areas below their canopies and nutrient poor areas at inter-shrub spaces (Chapter 2). In this landscape, performance of <i>Schismus</i> is favored around <i>Ambrosia</i> during years with good precipitation. Nevertheless, at any given growing season, shading and water interception by shrub canopies are the most influential factors on <i>Schismus</i> performance. Given that germination was consistently low below Ambrosia canopies, the consequences of <i>Schismus-Ambrosia</i> interactions might not be as straightforward as predicted by the individual effect of Ambrosia on <i>Schismus</i> . In fact, <i>Ambrosia</i> might actually reduce realized <i>Schismus</i> densities. Conversely, inter-specific competition with <i>Schismus</i> regulates <i>Ambrosia</i> seedling survival. Thus, high-density stands of <i>Schismus</i> might generate a negative feedback on the dynamics of favorable areas associated with shrubs; ultimately limiting <i>Schismus</i> abundance. I design a modeling framework to test this hypothesis and present several predictions about the long-term demographic consequences of reciprocal interactions between <i>Schismus</i> and <i>Ambrosia</i> (Chapter 4). 2009-02-18 English text The Ohio State University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=osu1233264311 http://rave.ohiolink.edu/etdc/view?acc_num=osu1233264311 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws. |
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NDLTD |
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English |
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NDLTD |
| topic |
Ecology Invasive species demography spatial heterogeneity Islands of fertility <i>Schismus barbatus</i> <i>Ambrosia dumosa</i> Desert ecology |
| spellingShingle |
Ecology Invasive species demography spatial heterogeneity Islands of fertility <i>Schismus barbatus</i> <i>Ambrosia dumosa</i> Desert ecology Rodriguez-Buritica, Susana Effects of the spatial heterogeneity formed by <i>Ambrosia dumosa</i> on individual and population growth of the invasive grass <i>Schismus barbatus</i> |
| author |
Rodriguez-Buritica, Susana |
| author_facet |
Rodriguez-Buritica, Susana |
| author_sort |
Rodriguez-Buritica, Susana |
| title |
Effects of the spatial heterogeneity formed by <i>Ambrosia dumosa</i> on individual and population growth of the invasive grass <i>Schismus barbatus</i> |
| title_short |
Effects of the spatial heterogeneity formed by <i>Ambrosia dumosa</i> on individual and population growth of the invasive grass <i>Schismus barbatus</i> |
| title_full |
Effects of the spatial heterogeneity formed by <i>Ambrosia dumosa</i> on individual and population growth of the invasive grass <i>Schismus barbatus</i> |
| title_fullStr |
Effects of the spatial heterogeneity formed by <i>Ambrosia dumosa</i> on individual and population growth of the invasive grass <i>Schismus barbatus</i> |
| title_full_unstemmed |
Effects of the spatial heterogeneity formed by <i>Ambrosia dumosa</i> on individual and population growth of the invasive grass <i>Schismus barbatus</i> |
| title_sort |
effects of the spatial heterogeneity formed by <i>ambrosia dumosa</i> on individual and population growth of the invasive grass <i>schismus barbatus</i> |
| publisher |
The Ohio State University / OhioLINK |
| publishDate |
2009 |
| url |
http://rave.ohiolink.edu/etdc/view?acc_num=osu1233264311 |
| work_keys_str_mv |
AT rodriguezburiticasusana effectsofthespatialheterogeneityformedbyiambrosiadumosaionindividualandpopulationgrowthoftheinvasivegrassischismusbarbatusi |
| _version_ |
1719427778221178880 |