Measuring habitat fragmentation: An evaluation of landscape pattern metrics

Abstract

Summary Landscape patterns influence a range of ecological processes at multiple spatial scales. Landscape pattern metrics are often used to study the patterns that result from the linear and nonlinear interactions between spatial aggregation and abundance of habitat. However, many class‐level pattern metrics are highly correlated with habitat abundance, making their use as a measure of habitat fragmentation problematic. We argue that a class‐level pattern metric should be (1) able to differentiate landscapes across a range of spatial aggregations, and (2) independent of habitat abundance, if it is to be used to distinguish between effects of habitat amount and fragmentation. Based on these criteria and using both simulated and actual landscapes, we evaluated 64 class‐level pattern metrics. These metrics were reclassified into four groups based on their correlation with aggregation and abundance. Among all these metrics, nine were considered robust for fragmentation measurements, which cover most of the characteristics that define pattern, including core area, shape, proximity / isolation, contrast, and contagion / interspersion. Optimal metrics for individual studies will depend on both biological rationales and statistically robust metrics that are appropriate for achieving each study objectives.