1. ^*,  Natural Resource Ecology Laboratory and ^† Departments of Entomology and Statistics, Colorado State University, Fort Collins, Colorado 80523, USA

Abstract

Gardner and Ashby¹ and May² challenged the tenet that ecological stability increases with species diversity. But May concluded that if species are arranged in 'blocks', stability restrictions are relaxed allowing for greater diversity than in the absence of blocking. Recent investigations suggest that communities may contain tightly coupled subunits whose numbers may increase with diversity^3–6. McNaughton⁷ suggested that species may be arranged in resource compartments and that, within these compartments, species interaction strength would decline as diversity increased. Pimm⁸ found little evidence of food-web compartmentation within habitats and few examples between habitats but cautioned that binary data sets based on connectedness were not optimal for detecting compartmentation. We provide evidence of resource compartmentation based on structural characteristics of a belowground connectedness web⁹ and on biomass estimates and nitrogen flux rates from its energy flux-web description. Using other food webs, we demonstrate that the relationship between structure and diversity is similar for different resource compartments, suggesting that these compartments behave as entities.