On the relative importance of the effects of selection and complementarity as drivers of diversity-productivity relationships in Mediterranean shrublands

International audienceExtensive research has been devoted to understanding the role of biodiversity as a driver of ecosystem functioning.However, no previous study has evaluated the relative contribution of complementarity and selection to productivity inshrublands. We have attempted to do this for a Mediterranean shrubland dominated by Quercus coccifera, Cistus albidus,Ulex parviflorus and Rosmarinus officinalis. We found a highly significant and linear positive relationship betweenproductivity and species richness. No selection effect was apparent, but both the complementarity and net effects werehighly significant. The magnitude of these effects increased from two to three species, but became non-significant in thefour-species mixtures. Analysis of pairwise interactions revealed that legumes did not promote overyielding.Complementarity was mostly driven by Cistus, which always performed better when growing with other species thanwhen growing with conspecifics. Our results are an addition to the still scarce literature dealing with diversityproductivity relationships in communities dominated by woody species, and show that methodologies commonlyused to assess complementarity may not provide a precise estimation when a given species has negative effects on itsconspecifics