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Brigham Young University (2021)

Fire and Rodent Consumer Effects on Plant Community Assembly and Invasion in North American Deserts

Stanton, Rebekah L.,

Titre : Fire and Rodent Consumer Effects on Plant Community Assembly and Invasion in North American Deserts

Auteur : Stanton, Rebekah L.,

Université de soutenance : Brigham Young University

Grade : Doctor of Philosophy (PhD) 2021

Résumé
This dissertation explores the differential effects of fires and rodent communities on native and invasive desert plant communities. Chapter one examines the impacts of fire and repeat fires on fuel loads in two different Utah desert sites, one in the cool Great Basin Desert and one in the hyper-arid Mojave Desert, over the course of four years. We found that both desert sites responded with varying intensities to a single burn, but the effects of a reburn were not as pronounced. We also found that our Great Basin Desert site had a stronger response to fire than our Mojave Desert site, producing a higher plant fuel loads that could potentially exacerbate the changing fire regimes. These data can be used to help map the effects that climate change may have on fuel loads and the fire potential of these deserts. Chapter two uses a full factorial experimental design to compare the effects of rodent herbivory and fire on native versus invasive seedlings at our Mojave Desert field site. We found that rodent herbivory has a more negative impact on the survival of native seedlings than invasive seedlings. This could be because the invasives are grasses that tend to tolerate herbivory better than the native shrubs and forbs. Chapter three again uses a full factorial experimental design to assess the impacts of rodents and fire on the fate of native and invasive seeds at our field site in the Mojave Desert. We found that rodents removed seeds, and they did show preferences for some species of seed over others, but these preferences were not different between native and invasive seeds or seed mass. We propose that the preferences may be influenced by other seed traits such as water content, handling time or physical and chemical defenses. As with the seedlings in chapter two, fire did not have any impact on rodent seed preferences. These data highlight the importance of considering rodent effects on seeds used in restoration effects following wildfires.

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Page publiée le 4 janvier 2022