|Van Ruijven, Jasper|
Submitted to: The American Naturalist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/23/2013
Publication Date: 1/2/2014
Publication URL: http://handle.nal.usda.gov/10113/59493
Citation: Gross, K., Cardinale, B.J., Fox, J.W., Gonzalez, A., Loreau, M., Polley, H.W., Reich, P.B., van Ruijven, J. 2014. Species richness and the temporal stability of biomass production: A new analysis of recent biodiversity experiments. The American Naturalist. 183(1):1-12. Interpretive Summary: The amount of growth achieved by groups of plant or algal species (communities) varies among years as a result of year to year differences in weather. Among-year variation in growth may be smaller in communities that contain many than few species, but the question of why this 'species richness effect' occurs remains to be resolved. We studied effects of increasing the number of species on among-year variation in growth of grassland and freshwater algal communities using data from 27 recent experiments. Among-year variability in growth was smaller in grassland communities with many than few plant species because different species were favored by the differences in weather conditions among years. Conditions that were favorable for growth of some species were not favorable for others. In contrast, the number of species had little effect on variability in growth of algal communities. Our results indicate the importance of maintaining or increasing the number of plant species in grasslands as a means to increase the year-to-year reliability of these systems to produce vegetation to support the livestock upon which a growing human population depends for food.
Technical Abstract: In this study, we investigate how species richness affects temporal stability of biomass production by analyzing 27 recent biodiversity experiments conducted in grassland and freshwater algal communities. We find that, in grasslands, increasing species richness stabilizes whole-community biomass production, but destabilizes the dynamics of individual species. Community-level stabilization is explained by the differing effects of species richness on the mean and variance of biomass production. In contrast, species richness has a minimal effect on algal community stability. In both grassland and algal systems, temporal correlations in species biomass are lower in polyculture than in monoculture. Finally, contrary to theoretical prediction, correlations among species across monocultures are unrelated to the strength of diversity's stabilizing effect on community productivity. These results provide the most comprehensive demonstration to date that increasing species richness stabilizes community level biomass production in grasslands, and are consistent with the idea that competitive interactions contribute to richness's stabilizing effect.