A landscape index of ecological integrity to inform landscape conservation

Abstract

Context: Conservation planning is increasingly using “coarse filters” based on the idea of conserving “nature’s stage”. One such approach is based on ecosystems and the concept of ecological integrity, although myriad ways exist to measure ecological integrity. Objectives: To describe our ecosystem-based index of ecological integrity (IEI) and its derivative index of ecological impact (ecoImpact), and illustrate their applications for conservation assessment and planning in the northeastern United States. Methods: We characterized the biophysical setting of the landscape at the 30 m cell resolution using a parsimonious suite of settings variables. Based on these settings variables and mapped ecosystems, we computed a suite of anthropogenic stressor metrics reflecting intactness (i.e., freedom from anthropogenic stressors) and resiliency metrics (i.e., connectivity to similar neighboring ecological settings), quantile-rescaled them by ecosystem and geographic extent, and combined them in a weighted linear model to create IEI. We used the change in IEI over time under a land use scenario to compute ecoImpact. Results: We illustrated the calculation of IEI and ecoImpact to compare the ecological integrity consequences of a 70-year projection of urban growth to an alternative scenario involving securing a network of conservation core areas (reserves) from future development. Conclusions: IEI and ecoImpact offer an effective way to assess ecological integrity across the landscape and examine the potential ecological consequences of alternative land use and land cover scenarios to inform conservation decision making.