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Disturbance-mediated trophic interactions and plant performance.
1Department of Environmental Studies, University of California, Santa Cruz, CA, USA. belderd@uchicago.edu
Oecologia
|October 6, 2005
Summary
Flooding indirectly harms riparian plants by altering herbivore communities, increasing grasshopper damage and reducing plant survival, despite direct positive effects of floods. This highlights the crucial role of indirect disturbance effects on plant communities.
Area of Science:
- Ecology
- Community Ecology
- Disturbance Ecology
Background:
- Disturbances like flooding significantly shape ecological communities, but their indirect effects are understudied.
- Annual flooding in riparian zones alters arthropod communities, potentially impacting plant species through changes in herbivory.
Purpose of the Study:
- To investigate the indirect effects of annual flooding on the riparian plant Mimulus guttatus.
- To determine how altered arthropod communities, specifically herbivores and predators, influence plant survival, growth, and reproduction.
Main Methods:
- An experiment excluded arthropod predators and herbivores from plots in both flooded and non-flooded riparian areas.
- The impact of these manipulations on Mimulus guttatus was assessed over two years.
Main Results:
- Flooding had a direct positive effect on M. guttatus, but indirect effects significantly reduced plant survival.
- Increased grasshopper herbivory in non-flooded sites was the primary driver of reduced plant survival, while leafhopper effects in flooded sites were weaker.
- Predator exclusion experiments showed that while predators could reduce leafhopper damage, this did not translate to increased plant survival or reproduction.
Conclusions:
- Indirect effects of flooding, mediated by changes in herbivore communities, are critical for riparian plant survival.
- Shifts in herbivore composition, particularly increased grasshopper abundance, pose a greater threat to plant survival than direct flood effects or predator-prey interactions.
- Flooding impacts riparian plant communities not only through direct abiotic factors but also by altering trophic interactions via changes in arthropod communities.