Over a decade of research shows that the services ecosystems provide to humanity can be affected by biodiversity loss. Yet the ability to predict the consequences of species loss on ecosystem functioning has proved elusive. In part this is because conventional approaches to understanding the role of biodiversity in the maintenance of ecosystem functioning have done
so in assembled communities which do not reflect natural population densities or extinction patterns. A series of empirically informed realistic biodiversity manipulations were performed in contrasting unitrophic marine communities. The aim was to test whether species contributions to community biomass can be used as surrogate measures of their contribution to ecosystem processes, as this could be used to predict the short term ('worst case scenario') consequences of species loss for ecosystem processes. The functional contribution of species was directly proportional to their contribution to community biomass
in a 1: I ratio. This relationship was consistent across three contrasting marine ecosystems and three ecosystem processes. Hence population biomass estimates can be used to predict worst case scenarios of the decline in ecosystem processes with species loss. A best case scenario was also modeled in which biomass loss associated with species extinction was fully compensated for by the extant species with the highest per capita contribution to ecosystem
processes. When combined, the best and worst case scenarios provide an estimate of the maximum and minimum number of species required to maintain different levels of ecosystem processes. Such estimates can be useful for environmental managers as there is a current lack of understanding of the processes which govern compensation of ecosystem function by
extinction resilient species in nature, inhibiting the generation of more realistic long term biodiversity-ecosystem function relationships.