Description: This vector line layer is attributed with distance measures generated from Linkage Mapper version 0.7.5 (McRae & Kavanagh 2011). Note Section 2.8 WHCWG (2012) concerning application of Linkage Mapper in the Columbia Plateau project area. Euclidean distance = shortest straight-line distance between two HCAs. Cost-weighted distance = minimum cost-weighted distance an animal can accumulate moving from one HCA to another. Cost-weighted distance is equal to the total resistance accumulated moving along the least-cost path between the two HCAs. Cost-weighted/Euclidean distance ratio = ratio of cost-weighted to Euclidean distance between two HCAs. Higher ratios mean least-cost corridors are longer or have higher resistance. Processing by WHCWG (2013) added attributes to the stick layer: current flow centrality, effective resistance, and ratio of cost-weighted distance to effective resistance. Links with high centrality scores indicate the importance of the links for maintaining network connectivity. Effective resistance values provide a measure of connectivity that complements cost-weighted distances by taking all pathways into account (not just the least-cost path). Given a least-cost corridor and the resistance surface used to create it, effective resistance measures connectivity in a way that integrates the corridor width and number and quality of alternative pathways available within a corridor. The effective resistance of a corridor decreases (and the cost-weighted distance/effective resistance ratio increases) when corridors are wider or provide high-quality alternatives to the least-cost path. For more details on effective resistance measures, see McRae et al. (2008). Using circuit theory to model connectivity in ecology, evolution, and conservation. Ecology 10: 2712-2724.
Description: Habitat concentration areas (HCAs) are defined as significant habitat areas that are expected or known to be important for focal species based on survey data or habitat association modeling. HCAs provide locations from which to model linkages. This set of HCA polygons contain a measure of network centrality.
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Description: This vector line layer is attributed with distance measures generated from Linkage Mapper version 0.7.5 (McRae & Kavanagh 2011). Note Section 2.8 WHCWG (2012) concerning application of Linkage Mapper in the Columbia Plateau project area. Euclidean distance = shortest straight-line distance between two HCAs. Cost-weighted distance = minimum cost-weighted distance an animal can accumulate moving from one HCA to another. Cost-weighted distance is equal to the total resistance accumulated moving along the least-cost path between the two HCAs. Non-weighted least-cost path length = length of the least-cost movement route, without accounting for cost. Cost-weighted/Euclidean distance ratio = ratio of cost-weighted to Euclidean distance between two HCAs. Higher ratios mean least-cost corridors are longer or have higher resistance. Cost-weighted/non-weighted path length ratio = ratio of cost-weighted distance to the non-weighted least-cost path length. This is equivalent to the average per-cell resistance encountered moving along the least-cost route between two HCAs. High values indicate pathways that pass through low quality movement habitat or across barriers. Note that least-cost paths lines are calculated and mapped only to provide identifiable placeholders for each linkage, and to provide estimates of relative linkage quality. Given the limitations of our models and our base data these lines developed from 1-grid-cell-wide routes are not meaningful for planning purposes. Processing by WHCWG (2013) added attributes to the LCP layer: current flow centrality, effective resistance, and ratio of cost-weighted distance to effective resistance. Links with high centrality scores indicate the importance of the links for maintaining network connectivity. Effective resistance values provide a measure of connectivity that complements cost-weighted distances by taking all pathways into account (not just the least-cost path). Given a least-cost corridor and the resistance surface used to create it, effective resistance measures connectivity in a way that integrates the corridor width and number and quality of alternative pathways available within a corridor. The effective resistance of a corridor decreases (and the cost-weighted distance/effective resistance ratio increases) when corridors are wider or provide high-quality alternatives to the least-cost path. For more details on effective resistance measures, see McRae et al. (2008). Using circuit theory to model connectivity in ecology, evolution, and conservation. Ecology 10: 2712-2724.
Description: Barriers are areas where landscape features impede wildlife movement between habitat concentration areas (HCAs). Least-cost modeling methods (see more at<http://www.circuitscape.org/linkagemapper>) identify and rank barriers by their impact and quantify the extent to which restoration may improve connectivity. Barriers may be partial or complete, and they may be natural (e.g., rivers, cliffs) or human-made (e.g., urban areas, highways, some types of agriculture). Not all barriers are restorable.
Description: Pinch-points are “bottlenecks” where wildlife movement is funneled within linkages. Pinch-point modeling methods are based on electrical circuit theory. Locations where current is very strong are constrictions within linkages and represent areas most vulnerable to being severed (see more at <http://www.circuitscape.org> /linkagemapper). Pinch-points can be the result of both natural and human-made landscape features.