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- All Subjects: desert
- Creators: Sabo, John L
- Creators: Bell, Matt
River and riparian areas are important foraging habitat for insectivorous bats. Numerous studies have shown that aquatic insects provide an important trophic resource to terrestrial consumers, including bats, and are key in regulating population size and species interactions in terrestrial food webs. Yet these studies have generally ignored how structural characteristics of the riverine landscape influence trophic resource availability or how terrestrial consumers respond to ensuing spatial and temporal patterns of trophic resources. Moreover, few studies have examined linkages between a stream's hydrologic regime and the timing and magnitude of aquatic insect availability. The main objective of my dissertation is to understand the causes of bat distributions in space and time. Specifically, I examine how trophic resource availability, structural components of riverine landscapes (channel confinement and riparian vegetation structure), and hydrologic regimes (flow permanence and timing of floods) mediate spatial and temporal patterns in bat activity. First, I show that river channel confinement determines bat activity along a river's longitudinal axis (directly above the river), while trophic resources appear to have stronger effects across a river's lateral (with distance from the river) axis. Second, I show that flow intermittency affects bat foraging activity indirectly via its effects on trophic resource availability. Seasonal river drying appears to have complex effects on bat foraging activity, initially causing imperfect tracking by consumers of localized concentrations of resources but later resulting in disappearance of both insects and bats after complete river drying. Third, I show that resource tracking by bats varies among streams with contrasting patterns of trophic resource availability and this variation appears to be in response to differences in the timing of aquatic insect emergence, duration and magnitude of emergence, and adult body size of emergent aquatic insects. Finally, I show that aquatic insects directly influence bat activity along a desert stream and that riparian vegetation composition affects bat activity, but only indirectly, via effects on aquatic insect availability. Overall, my results show river channel confinement, riparian vegetation structure, flow permanence, and the timing of floods influence spatial and temporal patterns in bat distributions; but these effects are indirect by influencing the ability of bats to track trophic resources in space and time.
The project intersects the environmental humanities, critical theory, and cultural studies with the Desert Southwest. It explores the fullness of desert places with regard to cultures, borders, and languages, as well as nonhuman forces and intensities like heat, light, and distance. Dispelling the dominant notion of desert as void or wasteland, it sets a stage to suit the polyvocality of desert place. My work is interdisciplinary because the desert demands it. It begins with Cormac McCarthy’s Blood Meridian in order to reorient readers towards the rupture of the US War With Mexico which helped set the national and cultural borders in effect today. I then explore Denis Villeneuve’s film Sicario to emphasize the correlation between political hierarchy and verticality; those who can experience the desert from above are exempt from the conditions below, where Urrea’s The Devil’s Highway and Gaspar de Alba’s Desert Blood take place. The novels expose the immanence and violence of being on the ground in the desert and at the lower end of said hierarchies. Analyzing Yuri Herrera’s Signs Preceding the End of the World and Mora’s Encantado enables what I term a desert hauntology to produce a desert full of memory, myth, ancestors, and enchantment. Finally, the project puts visual artists James Turrell and Rafa Esparza in conversation to discover a desert phenomenology. The result is an instigation of how far is too far when decentering the human, and what role does place-based art play in creating and empowering community.
John Ford was from Maine. Georgia O’Keeffe, from Wisconsin. Edward Abbey, Pennsylvania. As someone born and raised in the Desert Southwest, I’ve written the project I have yet to encounter.