The recognition that the numbers and types of species in a community influence the functioning of ecosystems has catalyzed the research of a generation of scientists. The relationship between biodiversity and ecosystem functioning (BEF) is most often examined by controlling species richness and randomizing community composition. In natural systems, biodiversity changes occur as part of metacommunity assembly processes. Focusing on community assembly and the functioning of ecosystems (CAFE), by integrating both species richness and composition changes through species gains, losses, and changes in abundance, will better reveal how changes to communities will impact ecosystem function. We synthesize the BEF and CAFE perspectives using an ecological application of the Price equation (Fox and Kerr 2012), which partitions the contributions of richness and composition to ecosystem function. We demonstrate the utility of this method with a novel graphical approach and empirical examples of environmental perturbations in terrestrial and marine ecosystems affecting plant and mammal communities.
The CAFE approach reveals important contributions of composition, over and above species richness changes, to ecosystem function. Examples of species invasions showed that changes in species richness and composition can work in concert to magnify ecosystem function changes or antagonistically to minimize ecosystem function impacts. Furthermore, we show how the CAFE approach can highlight, through time, the compositional and abundance-based changes that allow for the recovery of pre-disturbance levels of ecosystem function in small rodent communities. Considering how communities change in an integrative fashion, rather than focusing on one axis of community structure at a time, will improve our ability to anticipate and predict changes in ecosystem function. Considering the CAFE approach in studies of ecosystem function illustrates the importance of metacommunity processes for explaining the linkages between diversity, ecosystem function, and bridges knowledge derived from experimental and naturally-occurring communities.