Terrestrial Resilience: Permeability

Permeability refers to the degree to which a landscape sustains ecological processes and supports movement of many
species by virtue of the structural connectedness of its natural systems (Meiklejohn et al 2010). We used resistant
kernel analysis (Compton et al. 2007) to map permeability as a focal statistic based on the resistance data from the
terrestrial condition dataset. The analysis evaluates the capacity for ecological flow outward from each focal
cell into its local neighborhood up to a maximum of 3-km, then combines the results into a final, study-wide surface.
 
Perm_Score: Our permeability analysis evaluates the connectivity of a focal cell to its ecological neighborhood when the cell is viewed as a source; in other words, it asks the question: “to what extent are ecological movements outward from that cell impeded or facilitated by the surrounding landscape?” Thus, permeability analysis starts with a focal cell and looks at the resistance to ecological movement outward in all directions through the local neighborhood. As resistance increases, movement or flow is impeded or stopped altogether. Areas of no resistance allow the flow to proceed until a user-specified maximum distance (3 km) is achieved. Therefore, cells grow further in directions of low resistance. Each 270m pixel has been assigned a terrestrial permeability score, with values standardized on a 0-100 scale. Higher values indicate the landscape is relatively more permeable to terrestrial species movement than lower values. Terrestrial Permeability was combined with Topoclimate Diversity to create Resilience values.

These data are part of a land facet terrestrial resilience project created for the Pacific Northwest to identify the most resilient terrestrial sites in the Northwest U.S. that will collectively and individually best sustain native biodiversity even as the changing climate alters current distribution patterns. The central idea is that by mapping key geophysical features and evaluating them for landscape characteristics that buffer against the effects of climate change, we can identify the most resilient places in order to guide future conservation investments. All the datasets, along with the full report containing methods and maps is available at: http://nature.ly/resilienceNW

See a gallery of all datasets from this report on Data Basin:  http://nplcc.databasin.org/galleries/e41a3ea84e78463bbf9f03ce2f8e9205