|De Mazancourt, Claire|
|De Luca, Enrica|
|Van Ruijven, Jasper|
Submitted to: Ecology Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/16/2013
Publication Date: 5/1/2013
Citation: De Mazancourt, C., Isbell, F., Larocque, A., Berendse, F., De Luca, E., Grace, J.B., Haegeman, B., Polley, H.W., Roscher, C., Schmid, B., Tilman, D., Van Ruijven, J., Weigelt, A., Wilsey, B.J., Loreau, M. 2013. Predicting ecosystem stability from community composition and biodiversity. Ecology Letters. 16:617-625. Interpretive Summary: Year-to-year variability in biomass production of plant communities can be reduced by increasing the number of plant species in the community. The mechanisms involved in stabilizing production remain contentious, however. We use theory and information from monocultures of the species present in plant communities to mathematically test the relative roles of three mechanisms in stabilizing production: (1) differences in species’ responses to environmental variation, (2) the general tendency for production to be greater in species polycultures or communities than monocultures, and (3) decreased observation error. Calculations were tested using field measurements from four long-term grassland diversity experiments. Our mathematical estimate explains 21-53% of the observed variability in community production in these experiments. The relative importance of the three mechanisms in stabilizing production differed among experiments at different locations. Differences in species’ responses to environmental variation contributed more to stabilizing production at locations where the environment varied widely among years than was relatively constant, for example. Our approach could be used to predict the stability of plant production and other functional aspects of ecosystems from knowledge of the responses of individual species to environmental variation.
Technical Abstract: The intuitive idea that biodiversity allows different species to compensate for each other and thereby leads to more stable communities was challenged by later theoretical work. The paradox can be resolved by the fact that diversity often has a dual effect on community stability: it stabilizes community biomass, while at the same time destabilizing individual species abundances. Many experiments have confirmed the stabilising effects of biodiversity on ecosystem properties. The mechanisms through which stabilisation occurs, however, are still contentious. Here we expand previous theory to derive an analytical approximation for the coefficient of variation of total community biomass in polycultures that can be estimated independently from replicated monocultures. We show that biodiversity stabilises community biomass through three mechanisms: (1) asynchrony in species’ responses to the environment, which operates when environmental stochasticity is relatively strong, (2) overyielding in polycultures, which operates when demographic stochasticity is relatively strong, and (3) decreased observation error. We validate our approximation using simulation data, and test it with empirical data from 4 long-term grassland biodiversity experiments. Our approximation explains 21-53% of the observed variability in community biomass in these experiments, more than does species richness (11-36%). Our approach calls for a re-evaluation of the mechanisms that have been proposed so far, and offers a promising avenue to predict the stability of ecosystem services in the face of global environmental changes.