Oecologia

, Volume 119, Issue 2, pp 265–274

Relative strengths of top-down and bottom-up forces in a tropical forest community

  • Lee A. Dyer
  • Deborah K. Letourneau
Article

DOI: 10.1007/s004420050785

Cite this article as:
Dyer, L. & Letourneau, D. Oecologia (1999) 119: 265. doi:10.1007/s004420050785

Abstract

We tested integrative bottom-up and top-down trophic cascade hypotheses with manipulative experiments in a tropical wet forest, using the ant-plant Piper cenocladum and its associated arthropod community. We examined enhanced nutrients and light along with predator and herbivore exclusions as sources of variation in the relative biomass of plants, their herbivores (via rates of herbivory), and resident predaceous ants. The combined manipulations of secondary consumers, primary consumers, and plant resources allowed us to examine some of the direct and indirect effects on each trophic level and to determine the relative contributions of bottom-up and top-down cascades to the structure of the community. We found that enhanced plant resources (nutrients and light) had direct positive effects on plant biomass. However, we found no evidence of indirect (cascading through the herbivores) effects of plant biomass on predators or top predators. In contrast, ants had indirect effects on plant biomass by decreasing herbivory on the plants. This top-down cascade occurred whether or not plant resources were enriched, conditions which are expected to modify top-down forces.

Key words Ant-plant Trophic cascade Soil nutrients Piper Tropical forest 

Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • Lee A. Dyer
    • 1
  • Deborah K. Letourneau
    • 1
  1. 1.Western Colorado Center for Tropical Research, Mesa State College, Grand Junction, CO 81502, USA e-mail: ldyer@mesa5.mesa.colorado.edu, Tel. +1-970-2481124, Fax: +1-970-2481700US
  2. 2.Department of Environmental Studies, 214 College Eight, University of California, Santa Cruz, CA 95064, USAUS

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