Chapter 9 - Community structure

Abstract

Communities can be described as the diversity of species, the complexity of food web interactions, or the composition of functional groups. A variety of metrics have been developed to describe and compare species diversity, differing primarily in their emphasis on species richness or abundance. Food web complexity reflects the degree to which all species are represented in the model. Food webs are seen to be more complex when insects, or even arthropods, are represented at the same taxonomic level as are plants and vertebrates. Functional groups combine species according to defined functions, for example, primary producer, herbivore, predator, or detritivore, but many insects can be placed in different functional groups during different life stages. Community structure varies at global and regional or landscape levels and typically reflects latitudinal and landscape gradients in ecosystem productivity and habitat quality. Metacommunities can be distributed across landscapes in the same way as are metapopulations, based on distribution of suitable habitats.