Risk-Sensitive Foraging Facilitates Species-Level Trophic Cascades Among Terrestrial Mammals: A Meta-Analysis
Thomas P. Rooney (Advisor), John O. Stireman Iii (Committee Member), Yvonne M. Vadeboncoeur (Committee Member)
Master of Science (MS)
The widespread removal of large carnivores from terrestrial ecosystems may be contributing to plant species loss and biotic homogenization through trophic cascades. A few plants not preferred by ungulates are increasing in abundance while the majority of preferred plants are in decline. A meta-analysis of recruitment gaps in browse-sensitive tree species demonstrated that failed recruitment coincided in time with carnivore loss. In all studies recruitment continued in nearby browsing refugia. A second meta-analysis revealed that the mechanism of mammalian herbivore-mediated trophic cascades contains a behavioral component. Foraging mammals exhibited higher giving-up densities (GUDs) when under higher predation risk. GUDs were highest in microhabitats perceived to be risky when predators were present, intermediate in safe microhabitats when predators were present, and lowest in safe and risky microhabitats in the absence of predators. Removing the landscape of fear may decrease spatial heterogeneity in plant communities, contributing to biotic homogenization.
Department or Program
Department of Biological Sciences
Year Degree Awarded
Copyright 2009, all rights reserved. This open access ETD is published by Wright State University and OhioLINK.