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Experimental Protocol for Manipulating Plant-induced Soil Heterogeneity
Published on: March 13, 2014
Diversity has stronger top-down than bottom-up effects on decomposition.
Diane S Srivastava1, Bradley J Cardinale, Amy L Downing
1Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia V6T 1Z4, Canada. srivast@zoology.ubc.ca
Ecology
|May 20, 2009
Summary
Decreased detritivore (consumer) diversity significantly reduces decomposition rates in detritus-based food webs. Resource diversity, however, had no net effect on decomposition, unlike in plant-based food webs.
Area of Science:
- Ecology
- Food web dynamics
- Biodiversity research
Background:
- Energy and nutrient flow between trophic levels depend on food web structure and species diversity.
- The combined impacts of trophic structure and diversity on energy and nutrient transfer are not well understood.
- Decomposition is a critical ecological process involving consumer-resource interactions.
Purpose of the Study:
- To investigate whether changes in consumer diversity affect resource consumption rates similarly to changes in resource diversity.
- To compare the top-down effect of detritivore diversity with the bottom-up effect of detrital diversity on decomposition.
- To analyze the influence of diversity on consumer-resource dynamics in detritus-based food webs.
Main Methods:
- A meta-analysis was conducted using 90 observations from 28 studies.
- The study compared the effects of detritivore (consumer) diversity and detrital (resource) diversity on decomposition.
- Data on detrital standing stock, consumer standing stock, and decomposition rates were analyzed.
Main Results:
- No significant effects of detrital or consumer diversity were found on detrital standing stock.
- Effects of diversity on consumer standing stock were inconclusive.
- Reductions in detritivore diversity led to significant decreases in decomposition rates.
- Detrital diversity exhibited variable positive and negative effects on decomposition, with no overall trend.
- The contrasting effects of top-down (consumer) versus bottom-up (resource) diversity were robust across analyses.
Conclusions:
- Detritivore diversity plays a crucial role in regulating decomposition rates in detritus-based food webs.
- Unlike in plant-herbivore systems, resource diversity does not have a consistent net effect on consumption in detritus-based food webs.
- The impact of species diversity on ecological processes may differ significantly between "green" and "brown" food webs, particularly after primary production.
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