Using model systems to address the biodiversity-ecosystem functioning process

Declines in biodiversity resulting from anthropogenic disturbance to ecosystems have focused attention on the role of biodiversity in ecosystem functioning. However, the high level of complexity of ecosystems has made this a difficult topic to investigate. Much simpler model systems incorporating small-scale, spatially delimited, artificial assemblages of species have been widely used recently to address the link between biodiversity and ecosystem functioning (BEF). Their simplicity lends tractability to these systems, but has also resulted in much criticism in the literature over their relevance. Here, we examine the strengths and limitations of model systems and examine how useful these systems might be in addressing several issues that are likely to represent future challenges to understanding BEF: spatial scale, multiple trophic levels, variation, environmental stochasticity and the choice of representative combinations of species. We find that model systems have already played an important role in enhancing our understanding of BEF and are likely to continue this role in the future. However, they do have important limitations, and it is essential to take these into account when putting results into the broader context of ecosystems and to improve the level of integration of results with those from other methodologies.