Network Importance developed by TerrAdapt for the Washington Habitat Connectivity Action Plan. This model assessed the relative importance of areas to the overall connectivity network.

One shortcoming of the core-corridor and permeability models is that they reveal the best routes through a landscape (between core areas, and locally to neighboring pixels, respectively), but they don’t reflect the relative frequency at which those routes are likely to be used given the distribution of habitat and the quality of habitat across an ecosystem. Routes connecting two large core areas containing substantial high quality habitat are much more likely to be used by dispersing individuals compared to routes that connect smaller and/or lower quality cores. The relative density is a function of the density of the population interacting with the patterns of resistance on the landscape, and is a measure of centrality in the network of connected habitats (i.e., areas with the high dispersal densities are central within the population, connecting more of the population than less central areas). An understanding of relative dispersal density is valuable in that it enables prioritization of the most central parts of the network connecting the most high quality habitat.

To address this gap, we calculated an index intended to reflect the relative dispersal density across the landscape for each ecosystem. The source of dispersal was the core areas and the dispersal density inside each core was the square root of the core area multiplied by the mean habitat quality of the core. Dispersal density decreased moving outwards from each core as a function of the square of cost distance, scaled from 1 to 0 as the cost distance from the core increased from 0 to the maximum cost distance of 100km. Summing these dispersal ‘kernels’ across all the cores yielded the final dispersal density. Areas with many large cores of high quality had very high dispersal density relative to areas with fewer, smaller cores of lower quality.

Network Importance developed by TerrAdapt for the Washington Habitat Connectivity Action Plan. This model assessed the relative importance of areas to the overall connectivity network.

One shortcoming of the core-corridor and permeability models is that they reveal the best routes through a landscape (between core areas, and locally to neighboring pixels, respectively), but they don’t reflect the relative frequency at which those routes are likely to be used given the distribution of habitat and the quality of habitat across an ecosystem. Routes connecting two large core areas containing substantial high quality habitat are much more likely to be used by dispersing individuals compared to routes that connect smaller and/or lower quality cores. The relative density is a function of the density of the population interacting with the patterns of resistance on the landscape, and is a measure of centrality in the network of connected habitats (i.e., areas with the high dispersal densities are central within the population, connecting more of the population than less central areas). An understanding of relative dispersal density is valuable in that it enables prioritization of the most central parts of the network connecting the most high quality habitat.

To address this gap, we calculated an index intended to reflect the relative dispersal density across the landscape for each ecosystem. The source of dispersal was the core areas and the dispersal density inside each core was the square root of the core area multiplied by the mean habitat quality of the core. Dispersal density decreased moving outwards from each core as a function of the square of cost distance, scaled from 1 to 0 as the cost distance from the core increased from 0 to the maximum cost distance of 100km. Summing these dispersal ‘kernels’ across all the cores yielded the final dispersal density. Areas with many large cores of high quality had very high dispersal density relative to areas with fewer, smaller cores of lower quality.