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This tool assigns an index of functional patch connectivity (IFPC) to each patch of a user-specified polygon layer. The smaller the index, the more isolated the patch is.
In this tool, connectivity is estimated from the organism’s point of view (hence the name ‘functional connectivity’) by using the ArcGIS Cost Distance tool, i.e. connectivity relates to how easily an individual can move from one patch to another, as the tool considers the features of the matrix between patches that can facilitate or impede individual movements. When only the Euclidean distance between each patch is considered, a patch close to another patch would be considered as not isolated, but if a barrier to individual movements exists between them, they can be functionally isolated, as no or very few individuals can move between these patches.
In addition, patch functional connectivity relates to the number of immigrating individuals in a patch, in turn often related to the size of the neighbouring patches, likely to host larger populations.
As the computation of cost distances is a long process, a threshold radius is specified, and only neighbouring patches located within this Euclidean distance from the focal patch are considered. In addition, the tool allows the user to specify two layers of patches: a first one representing the patches the user is interested in and for which IFPCs are calculated, and a second layer representing the possible neighbouring patches for which IFPC need not to be calculated.
The IFPC is calculated as the sum of the areas of the surrounding patches, weighed by the least cost of going between them and the focal patch, as shown in this
illustration:
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