This layer was created as part of Esri’s Green Infrastructure Initiative and is one of five newly generated companion datasets that can be used for Green Infrastructure (GI) planning at national, regional, and more local scales. If used together, these layers should have corresponding date-based suffixes (YYYYMMDD). The corresponding layer names are: Intact Habitat Cores, Habitat Connectors, Habitat Fragments, Habitat Cost Surface, and Intact Habitat Cores by Betweeness. These Esri derived data, and additional data central to GI planning from other authoritative sources, are also available as Map Packages for each U.S. State and can be downloaded from the Green Infrastructure Data Gallery.

 This layer represents Intact Habitat Cores, symbolized based on their connectivity importance (Betweenness Centrality (BC). BC provides a metric depicting each core’s importance in a connectivity network, thus illuminating each core’s relative contribution to facilitating landscape connectivity and potential species movement. BC represents the number of paths that flow through a given habitat core. It is normalized by the total number of shortest paths between all pairs of nodes, except those paths connecting immediate neighbors. High BC values reflect greater use of that core in traversing the network, thus elevating the core’s importance in facilitating connectivity when compared to cores of lower value. Every time you change your viewing extent, the layer dynamically recalculates to depict the most important cores, based on its betweenness centrality value.

 The Habitat Cost Surface layer was used to generate a comprehensive network of Least Cost Paths (LCPs) amongst the Intact Habitat Cores layer. This was accomplished using the Cost Connectivity tool which was introduced in ArcGIS 10.4 and ArcGISPro in 1.3. The resulting Habitat Connectors layer was then utilized as the network upon which BC was calculated. The Betweenness_Centrality function in the NetworkX Python library was used to first calculate the number of cost based optimal paths passing through each core and then dividing this number by the range of values in the LCP Routes field. This work was based on the NetworkX Parallel Betweenness example. 

Data Coordinate System: NAD_1983_Albers