The relationship between the number of species in an ecological community and the functional aspects of the ecosystem is usually studied experimentally by observing the effects of random changes in diversity. However, a study of rocky intertidal pools reveals that the nonrandom variation in species diversity that is characteristic of natural habitats yields better predictions of functional effects than experiments in which the species composition is altered randomly. Bracken et al. quantified the effects of both kinds of variation in seaweed diversity on nutrient dynamics (nitrogen uptake) in a set of tide pools in which the number of species increased as disturbance (caused by heavy surf) decreased. The effects of natural realistic variation were compared with the effects of artificial diversity gradients established by random groupings of species. Increased diversity in the “real-world” pools was associated with higher rates of nutrient acquisition by the plants, whereas the artificial communities showed no relationship. These results present new challenges for experimental ecologists studying the consequences of biodiversity loss in ecosystems.
*.* Source of Information : 15th February 2008 Science