Determinants of biodiversity regulate compositional stability of communities

The world is witnessing a decline in biodiversity which may be greater in magnitude than even previous mass-extinction events(1-3). This has rekindled interest in the relationships between biodiversity and the stability of community and ecosystem processes(4) that have been reported in some empirical studies(5-7), Diversity has been linked with community and ecosystem processess(8-14), but disputes remain over whether it is diversity, environmental factors or the variety of functional groups in a community that drive these patterns(15-21). Furthermore, it remains unclear whether variation in diversity resulting from species loss within communities has similar effects on stability as natural variation in diversity associated with gradients in factors that regulate diversity. We believe that, across larger ecological scales, extrinsic determinants of biodiversity such as disturbance regimes and site history may be the primary determinants of certain measures of community stability. Here we use controlled field experiments in savanna grasslands in southern India to demonstrate and explain how low-diversity plant communities can show greater compositional stability when subject to experimental perturbations characteristic of their native environments. These results are best explained by the ecological history and species characteristics of communities rather than by species diversity in itself.