Landscape Metrics: Past Progress and Future Directions

Abstract

This paper reviews progress in the field of landscape ecology related to the development of landscape metrics (i.e., spatial pattern indices). We first review the major formative historical developments that contributed to the coalescence of landscape metrics as a sub-field of landscape ecology and then examine recent literature highlighting several shortcomings related to their utility for understanding ecological processes and discuss several alternative approaches. Recent research recognizes some limitations of the patch-mosaic model (PMM), including the landscape metrics based on it, for capturing landscape heterogeneity and measuring functionality. Collapsing land cover information into nominal classes complicates identification of ecologically meaningful relationships and effective management. We explore several alternative methods for capturing landscape functionality and spatial heterogeneity including graph-based networks and gradient surface models with associated surface metrics. With complementary patch-based, gradient, and graph network models available, the goal for landscape ecologists is to select the correct approach, or combination of approaches, for investigating the issue at hand. Biases associated with the modifiable areal unit problem (MAUP) and its connection to heterogeneity and scale—both grain and extent—complicate these decisions, but empirical tools from spatial allometry may improve the ability for landscape ecologists to assess where metrics are capturing ecological processes versus the scale-dependency of the metrics themselves.