Introduction

Macroecology, the search to identify and understand the origin of patterns in the distribution and abundance of species is a major focus of ecology (Gaston & Blackburn, 2000). Knowledge of such patterns is central to formulating local, national and global conservation and land use policies, as well as to the effort to understand the principles governing ecosystem function and temporal dynamics. Many mathematical models have been proposed and tested against specific macroecological patterns (e.g. He & Legendre, 2002) but few have been tested against the wide array of spatial metrics that can be derived from spatially explicit census data. Moreover, many of these models contain adjustable parameters whose values are difficult to determine a priori, and it is often unclear whether fitting parameterized models to data yields predictive insight into ecosystems. By testing highly constrained theory against a variety of metrics, as opposed to testing parameter-laden theory against a small number of metrics, the search for plausible underlying pattern-generating mechanisms may be expedited.

Two types of spatial metric are of interest here – those that characterize the distributions of individual species and those that characterize spatial structure in a community of species. Table 6.1 lists and defines a diverse set of spatial metrics of both types. The metrics are defined in terms of a scale label, i, which is explained in Box 6.1. That box also illustrates the definitions of the spatial metrics using a simple example.