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Changes to vegetation architecture within a natural habitat can have profound impacts upon ecological community function, but the relative influence of vegetation architecture itself and potential indirect influences of associated food resources are often difficult to disentangle. I present the results of a three-year study designed to address the community level impacts of changes in big sagebrush (Artemisia tridentata) architecture and associated prey availability upon the ground-dwelling arthropod community. Three experimental sagebrush architecture treatments (low, intermediate, and high foliage density) and two levels of prey insect availability treatment (natural and baited/increased prey availability) were imposed in a sage-steppe ecosystem. The ground-dwelling spider (top predators) and insect (prey) response to all combinations of the six treatments were assessed through abundances in pitfall traps. Chapter 2 demonstrates that changes in a single shrub���s architecture did not markedly impact prey arthropod availability on the ground, though an overall increase in arthropod abundance was detected within baited shrubs. This indicates changes to vegetation architecture do not impact prey insect availability for ground-dwelling spiders. Thus, changes in shrub architecture and not the associated prey base directly alter the ground-dwelling spider community. Chapter 3 shows that architectural manipulation of a single sagebrush directly influences the ability of certain ground-dwelling spider guilds to persist beneath the shrub. Data within Chapters 2 and 3 support the conclusion that vegetation architecture directly affects ground-dwelling spider community structure and composition. Finally, Chapter 4 explores how the relative impacts of vegetation architecture and prey availability upon ecological communities can shift depending upon the spatial context in which the manipulations take place, given the differences in mobility of species within the grounddwelling spider and insect prey communities. Within this study, Diurnal and Nocturnal Wanderers responded to manipulations in prey availability at a larger spatial context (patches of 15 shrubs) while more stationary Trappers and Ambushers did not. Through simultaneous manipulation of vegetation architecture (Artemisia tridentata, big sagebrush) and associated insect prey base in different spatial contexts, this dissertation demonstrates that vegetation architecture directly affects ground-dwelling spider community organization at the species and guild levels of diversity. Shifts in spider (predator) functional diversity can ultimately impact arthropod decomposer and herbivore populations, influencing fundamental ecosystem processes such as decomposition and productivity.

Wildlife are under continuous pressure to adapt to new environments as more land area is converted for human use and human populations continue to concentrate in suburban and exurban areas. This is especially the case for terrestrial mammals, which are forced to navigate these habitat matrices on foot. One way in which mammals may occupy urbanized landscapes is by altering their temporal activity behavior. Typically, studies have found that mammals increase their nocturnal activity within urbanized environments to avoid overlap with humans. However, to date, the majority of studies on this topic have focused on single species, and studying whether this trend holds across an entire community has important ecological implications. Specifically, understanding how differences in species temporal activity response alters predator-prey dynamics and sympatric interspecies competition can provide insight into urban wildlife community assembly and provide a mechanistic understanding of species co-occurrence within these systems. In this study, we used data from a community science camera trapping project in northern Utah to elucidate how human influence alters the temporal activity behavior of five medium- to largesized mammals and how differences in species response affect predator-prey, human, and sympatric competitor temporal niche overlap. We found community-wide changes in activity across study sites, with increases in late night and midday activity and decreases in crepuscular activity within the more-urbanized site. However, species-specific behavioral changes varied, and these changes resulted in reduced overlap, especially between coyotes (Canis latrans) and their potential prey species. These results provide information on how human influence may alter community assembly and species-species interactions within a wildland-urban interface., University of Utah of Graduate Research Fellowship