Tuesday, August 7, 2007: 8:00 AM-11:30 AM
A4&5, San Jose McEnery Convention Center
OOS 7 - Trophic structure across systems: Case studies and synthesis
For more than a century, trophic interactions have been central to the conceptual unification of population, community and ecosystems ecology. The partitioning of biomass among functional feeding levels within ecosystems – trophic structure – historically has been seen as fundamentally constrained by available productivity, energy, or nutrients from the ‘bottom-up’, or driven from the ‘top-down’ by predator forcing and subsequent indirect effects (i.e., trophic cascades). Vigorous debates over the relative importance of resource or predator control of food web structure and the strength and ubiquity of trophic cascades across ecosystem types have yielded to a more nuanced view. Collaboration among ecologists working in different systems and cross-system comparisons driven by data have led to a greater appreciation for the multitude of factors that can influence trophic structure and alter the likelihood of indirect effects across multiple trophic levels. Recent research has focused on heterogeneity of trophic structure, including factors such as the diversity and behavior of consumers from the large (top predators) to the small (pathogens and parasites), nutrient stoichiometric constraints on consumption and growth patterns, and the ubiquity and magnitude of detrital pathways and subsidy effects across ecosystem boundaries. Speakers bring a broad range of expertise across ecosystems, taxa, and organizational scales, and all will synthesize theory, observational and experimental datasets, and conservation objectives with their specific themes.
Organizer:Daniel S. Gruner, University of California-Davis
Co-organizers:Elizabeth T. Borer, Oregon State University
Jonathan B. Shurin, University of British Columbia
Moderator:Daniel S. Gruner, University of California-Davis
8:00 AMTrophic structure: Introduction and historical overview
Donald R. Strong, University of California - Davis
8:20 AMBody size and the importance of bottom-up and top-down forces in Serengeti mammals
Anthony R. E. Sinclair, University of British Columbia, Justin Brashares, University of California, Berkeley
8:40 AMDifferential resilience of trophic structure to exploitation in continental shelf ecosystems
Kenneth Frank, Department of Fisheries and Oceans
9:00 AMTop-down and bottom-up controls on plant pathogens: Viral prevalence in grasslands
Elizabeth T. Borer, Oregon State University, Eric W. Seabloom, Oregon State University, Alison Power, Cornell University, Charles Mitchell, University of North Carolina, Chapel Hill
9:20 AMBottom-up control of herbivore-producer biomass ratios across ecosystems
Just Cebrian, Dauphin Island Sea Lab, Jonathan B. Shurin, University of British Columbia, Elizabeth T. Borer, Oregon State University, Bradley J. Cardinale, University of California, Santa Barbara, Melinda D. Smith, Yale University
9:40 AMBreak
9:50 AMExperimental evidence and meta-analysis of the effects of top-down and bottom-up control on coral reef primary producers
Jennifer E. Smith, National Center for Ecological Analysis and Synthesis
10:10 AMHow coupling between green and brown food webs alters trophic structure
Elizabeth M. Wolkovich, Dartmouth College, Kathryn L. Cottingham, Dartmouth College, Claire De Mazancourt, McGill University, Stuart Sandin, Scripps Oceanographic Institute, John C. Moore, Colorado State University
10:30 AMEffects of marine iguanas, fish, and crabs on the diversity of Galapagos rocky shore communities at different levels of productivity
Luis Vinueza, Oregon State University, Bruce A Menge, Oregon State University
10:50 AMInfluence of bird predation on herbivore abundance and understory tree growth in a northern forest ecosystem
W. Scott Schwenk, University of Vermont, Allan M. Strong, University of Vermont, Scott Sillett, Smithsonian Migratory Bird Center
11:10 AMPredator diversity and trophic interactions
Oswald J. Schmitz, Yale University

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