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New Mexico State University (2015)

Effects of urbanization on trophic interactions in a desert landscape

Davanon, Kristen A

Titre : Effects of urbanization on trophic interactions in a desert landscape

Auteur : Davanon, Kristen A

Université de soutenance : New Mexico State University

Grade : Master of Science (MS) Biology 2015

Résumé
Trophic systems can be affected by top-down (predators) and bottom-up (resources) impacts. Human activity can alter a trophic system by causing predators to avoid urban areas (top-down) or by providing increased resources through irrigation and introduction of non-native plants that attract herbivores and their predators (bottom-up). Both processes may constrain the recruitment of herbaceous plants. We examined the effect of increasing urbanization within Las Cruces, New Mexico, on a trophic system that included mammalian predators, mammalian prey, and herbaceous plants existing with natural shrubland vegetation surrounding urban structures. We tested the hypothesis that the degree of urbanization, measured as the density of urban structures, would have a negative effect on herbaceous plant recruitment, mediated by trophic interactions. Urbanization effects could be caused either by a top-down effect in which predator abundance is reduced in more dense exurban areas, or urbanization could involve a bottom-up effect by providing food and water resources to support increased prey and predators. We found increased rates of herbivory on seedlings and decreased herbaceous plant recruitment in more dense exurban. areas Patterns of overall rodent abundance, seed consumption rates,and jackrabbit activity did not vary with urbanization. however, we found increased cottontail and coyote activity in dense exurban areas, supporting the hypothesis that the effect of urbanization on plant recruitment is mediated by a bottom-up effect. Our results indicate the urbanization can have important indirect effects on adjacent ecosystems.

Sujets : Food chains (Ecology)—New Mexico—Las Cruces. Nature—Effect of human beings on

Présentation (NMSU Library)

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