Describing and analyzing landscape patterns: where are we now, and where are we going?
The description and analysis of landscape patterns became a central research issue in landscape ecology with the emergence of the pattern-process hypothesis (Turner and Gardner 1991). The earliest references to landscape pattern metrics or indices in the peerreviewed literature were in 1987 and 1988 (Fig. 1a). Gardner et al. (1987) compared the number, size, and perimeters of patches across real and simulated landscapes and established the neutral model concept for comparing landscape patterns. Krummel et al. (1987) demonstrated the first multi-scale index—a fractal dimension describing perimeter-area scaling— while Milne (1988) demonstrated an entire class of multi-scale indices based on fractal geometry. O’Neill et al. (1988) introduced the dominance and contagion indices, the latter of which extended the Shannon species diversity index (e.g. Pielou 1975) to describe the diversity of spatial adjacencies on a map. Those and other early methods capitalized on concepts or metrics developed in diverse fields such as information theory, percolation theory, classical ecology, and fractal geometry.