9 Community Structure A COMMUNITY IS COMPOSED OF ALL THE ORGANISMS OCCUPYING A SITE. The extent to which these organisms are co-evolved to form a consistent and recurring integrated community or represent ad hoc assemblages of loosely interacting species remains a topic of much discussion. | 9 Community Structure I. Approaches to Describing Communities A. Species Diversity B. Species Interactions C. Functional Organization II. Patterns of Community Structure A. Global Patterns B. Biome and Landscape Patterns III. Determinants of Community Structure A. Habitat Area and Complexity B. Habitat Stability C. Resource Availability D. Species Interactions IV. Summary A COMMUNITY IS COMPOSED OF ALL THE ORGANISMS OCCUPYING A SITE. The extent to which these organisms are co-evolved to form a consistent and recurring integrated community or represent ad hoc assemblages of loosely interacting species remains a topic of much discussion. Considerable research has been directed toward identifying spatial and temporal patterns in community structure and evaluating factors that determine community composition. Such efforts have become increasingly important to conservation efforts with recognition that many species depend on the presence of associated species. However comparison of community structures within or among broadly distributed community types that share few if any species requires approaches that are independent of the taxonomic composition of the community. Ecologists have developed a variety of nontaxonomic approaches to describing community structure providing different types of information to meet different objectives. The diversity of approaches has hindered comparison of communities described in different terms. Nevertheless distinct geographic patterns can be seen in community structure and some community types characterize particular habitat conditions. A number of factors determine community composition distribution and dynamics. This chapter focuses on approaches to describing community structure and on biogeographic patterns and underlying factors contributing to community structure. Temporal patterns in community structure are the focus of the next chapter. 251 252 9. COMMUNITY STRUCTURE I. APPROACHES TO DESCRIBING COMMUNITIES Although the .
