PARENT SESSION
Wednesday, August 9, 1:30-5:00 pm
Symposium 14 - The urban food web: how humans alter the state and interactions of trophic dynamics
Cotton Row, Mezzanine Level, Cook Convention Center
Organized by: PS Warren (pswarren@forwild.umass.edu), C Tripler, C Lepczyk, and J Walker
This symposium addresses the unification of food web theory, with its classic debates over the regulation of populations and communities, and the inventive new approaches by which urban ecologists examine the dynamics of coupled social-biophysical systems.
Humans in the urban food web: insights from integrating social and biophysical science approaches in Phoenix and Baltimore.
Warren, Paige*,1, Grove, J. Morgan2, Tarrant, Philip3, Adley, Erin4, Lerman, Susannah1, Shochat, Eyal3, 1 University of Massachusetts, Amherst, Amherst, MA2 USDA Forest Service, Burlington, VT3 Arizona State University, Tempe, AZ4 Purdue University, W. Lafayette, IN
ABSTRACT- Human activities dramatically change abundances, diversity, and composition of species. Little is known about how the most intense human activity, urbanization, alters food webs and trophic structure in biological communities. Experimental studies at the Central Arizona-Phoenix (CAP) LTER reveal surprising alterations in control of trophic dynamics. Supplemented resources, particularly water, increase and stabilize productivity, setting the stage for altered control of populations. Relative to outlying desert areas, top down influences appear to be weaker for birds and stronger for arthropods in urban environments. However, the nature of human provisioning and alteration of resources and predation varies within cities, according to our research at both CAP LTER and at the Baltiomore Ecosystem Study (BES LTER). Several social theories, including social stratification and the "ecology of prestige" have proposed to account for this variation. We find that different social processes appear to be altering different portions of the urban food web. For example, lifestyle factors, indicators for the "ecology of prestige", are better predictors of the presence of bird feeders at the neighborhood scale than are indicators of social stratification such as income level. There are important consequences of predicting the locations of bird feeders since birds exhibit evidence of greater competition with increasing numbers of bird feeders. By contrast, different sociodemographic factors predict the presence of outdoor cats, an important predator for birds. We propose a set of interdisciplinary tools and approaches for disentangling human influences on urban food webs. This kind of integration is essential for a comprehensive understanding and management of human-dominated environments.
Key words: urban ecology, food webs, birds