Disentangling community functional components in a litter-macrodetritivore model system reveals the predominance of the mass ratio hypothesis
Article first published online: 20 JAN 2014
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Ecology and Evolution
Volume 4, Issue 4, pages 408–416, February 2014
How to Cite
Ecology and Evolution 2014; 4(4):408–416
- Issue published online: 17 FEB 2014
- Article first published online: 20 JAN 2014
- Manuscript Revised: 8 JAN 2014
- Manuscript Accepted: 12 DEC 2013
- Manuscript Received: 7 DEC 2013
- Scientific Exchange Program
- New Member States of the EU and Switzerland. Grant Numbers: LC06073 , CZ.1.05/1.1.00/02.0073
- Grant Agency of the Czech Republic. Grant Number: GACR P505/12/1296
- NWO postdoctoral. Grant Number: NWO/819.01.017
- Community-weighted mean trait value;
- functional diversity;
- functional metrics;
- litter decomposition;
- trait dissimilarity
Recent investigations have shown that two components of community trait composition are important for key ecosystem processes: (i) the community-weighted mean trait value (CWM), related to the mass ratio hypothesis and dominant trait values in the community, and (ii) functional diversity (FD), related to the complementarity hypothesis and the divergence of trait values. However, no experiments controlling for the inherent dependence between CWM and FD have been conducted so far. We used a novel experimental framework to disentangle the unique and shared effects of CWM and FD in a leaf litter-macrodetritivore model system. We manipulated isopod assemblages varying in species number, CWM and FD of litter consumption rate to test the relative contribution of these community parameters in the decomposition process. We showed that CWM, but also the combination of CWM and FD, is a main factor controlling litter decomposition. When we tested individual biodiversity components separately, CWM of litter consumption rate showed a significant effect on decomposition, while FD and species richness alone did not. Our study demonstrated that (i) trait composition rather than species diversity drives litter decomposition, (ii) dominant trait values in the community (CWM) play a chief role in driving ecosystem processes, corroborating the mass ratio hypothesis, and (iii) trait dissimilarity can contribute in modulating the overall biodiversity effects. Future challenge is to assess whether the generality of our finding, that is, that dominant trait values (CWM) predominate over trait dissimilarity (FD), holds for other ecosystem processes, environmental conditions and different spatial and temporal scales.