Chapter 13 - Species Richness, Diversity and Packing

A great deal of time and expertise has been expended on the compilation of faunal lists for particular habitats, but the consequent increase in our understanding of the structure and functioning of animal communities or the impact on them of natural or man-induced change is still meagre. The body of quantitative theory on communities has continued to develop, especially following the lead given by the 'Hutchinson-MacArthur school'. Theory, while directing the way we organise and analyse our data, is also posing hypotheses and suggesting new analytical approaches at a rate that almost defeats our ability to test.

Linked to increased interest in conservation, the term biological diversity or biodiversity (Wilson,1988; Reaka-Kudla et al., 1997) - a measure of the total genetic and ecological diversity - has entered our vocabulary. A task for ecologists is to give a quantitative measure to this rather spiritual concept. Only by creating and applying reliable measures of diversity can we measure how it varies both spatially and temporally and thus recognise the influences that create and destroy it. There are numerous measures of diversity or ways of estimating species richness, which method is to be preferred will depend on the quality of the data, the sampling effort, community properties such as species number, community stability and the objectives of the study. In this chapter we will focus primarily on species diversity. It is axiomatic that the objectives and methods of analysis should be fully and carefully considered, before the field programme is undertaken. The methods of sampling are those outlined in Chapters 4 to 6 and Chapter 9, although the differential response of species to trapping is an indication for caution in respect of many of the methods in Chapter 7. The present chapter aims to describe the methods of handling and analysing data on animal communities (from guilds to continental faunas). Details of the theoretical studies and examples of fieldwork are given in MacArthur & Wilson (1967), MacArthur (1972), May (1973,1976), McClure & Price (1976), Cody & Diamond (1975) and Pianka (1976) and Pimm (1991).

13.1 Diversity 13.1.1 Description of alpha and Beta diversity 13.1.2 Species richness 13.1.3 Models for the S:N relationship 13.1.4 Non-parametric indices of diversity 13.1.5 Which model or index? 13.1.6 Comparing communities- diversity ordering 13.1.7 Procedure to determine diversity 13.1.8 Determining diversity 13.2 Similarity and the comparison and classification of samples 13.2.1 Measures of complementarity 13.2.2 Similarity indices 13.2.3 Multivariate analysis 13.3 Species packing 13.3.1 Measurement of inter-specific association 13.3.2 Measurement of resource utilization 13.3.3 Niche size and competition coefficients