Introduction

In order to understand ecological processes at multiple scales, ecological studies are often carried out over large regions (see Chapter 8). By doing so, most study areas include ecological processes that can act at different spatial and temporal scales (Dungan et al. 2002). In such cases, it is unlikely that the standard assumption of stationarity (i.e. the same mean, variance and isotropy; see Chapters 1 and 2) is valid. To analyse ecological data from large regions in a meaningful way, the region should therefore be partitioned into smaller, more homogeneous areas (i.e. patches) that are more likely to be governed by the same ecological process and hence stationary. Stratifying a region can also be useful for monitoring and managing resources by informing locally appropriate adjustments. There are two main approaches to spatially partition a region:

1. (1) grouping adjacent locations that have similar values of the indicator variable(s) by generating spatial clusters (Figure 9.1), or

2. (2) dividing the whole region into subareas, based on their degree of dissimilarity, by delineating boundaries between different areas (Figure 9.2).