Document: DAV-3-52-36
Understanding the ecological determinants of food-chain length: Recent advances.
POST, D.M.* 1,2
Cornell Univeristy, Ithaca, NY 14853, USA 1
Institute of Ecosystem Studies, Millbrook, NY 12545, USA 2
Abstract:
Food-chain length is an important characteristic of ecological communities that influences community structure, ecosystem function, and contaminant concentrations in top predators. In the 70 years since Charles Elton first noted that food-chain length was variable among natural systems, ecologists have considered numerous explanatory hypotheses, but few of those are supported by empirical evidence. Conventional wisdom, as expressed by major ecology textbooks, generally suggests that food-chain length is limited by resource availability or by the dynamic stability of food chain. However, recent work seriously challenges conventional wisdom. Here, I review recent advances in understanding the ecological determinants of food-chain length and place those results into the context of historically important hypotheses. I discuss both empirical evidence for ecosystem size and productivity as determinants of food-chain length, and theoretical evidence for the relationship between food-chain length and food web stability. I also discuss how the new empirical results challenge the widely cited Oksanen-Fretwell model for trophic interactions which assumes that productivity determines food-chain length. These recent studies highlight the need for further work on food-chain length and food web stability, and emphasize the need to tests of food-chain theory at the ecologically relevant scale of whole food webs.
Keywords: Food-chain length, ecosystem size, ecosystem productivity, food web models, dynamic stability
This abstract is being presented at: 8:45 AM in session:
Oral Session #39: Theoretical Ecology.