The high productivity, nutrient retention, and stability (resistance and resilience in response to pests, pathogens, and invasive weeds) observed in natural systems are frequently attributed to their high diversity (Tilman, 2000) . High productivity, nutrient retention, and stability are also associated with ecosystem sustainability. In much of the temperate world - as also in parts of the tropics - these aspects of ecosystem functioning have been achieved in highly simplified human-managed systems through subsidies in the form of fertilizers and pesticides. Over much of the tropical world, however, such fossil-energy-based subsidies continue to be an economically unviable option. Understanding the ecological underpinnings of the diversity-functioning relationship, therefore, is crucial to the design of sustainable human-managed tropical systems.