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Eastern Cougar Connectivity

Terrestrial habitat connectivity models for the South Atlantic Landscape Conservation Cooperative

Dates

Acquisition
2014

Summary

The connectivity result files from Circuitscape represent the "adjusted cumulative current density" flowing across the landscape for each of several species, at a 90-meter resolution across the South Atlantic Landscape Conservation Cooperative region. Rasters are classified using quantiles with 20 categories (each 5% of region) to integer scores from 1-20. 1 = lowest 5% of the landscape, 20= top 5% of landscape Expert opinion was used to define a resistance surface for each of the target animals, with higher resistance representing map units expected to be more difficult and dangerous for species to move through. A set of nodes for each species, with node points indicating center locations for potential source populations, are also [...]

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Attached Files

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EasternCougar.zip 32.69 MB
estrn_cougar_current.zip 18.08 MB
estrn_cougar_future.zip 14.6 MB
Extension: Eastern_Cougar_Connectivity.zip
thumbnail.png thumbnail 12.51 KB

Material Request Instructions

The Circuitscape current density outputs are in relative terms and cannot be directly converted to numbers of animals crossing a given pixel of habitat per unit time. Additional empirical studies can hopefully provide calibration. Until then, users should be aware that Circuitscape may show connections between nodes that are too difficult for any single animal of the target species to actually complete, even after taking into account the maximum node-node distance thresholds employed. Also, broad areas of suitable habitat may have low current densities compared to narrow "chokepoints" where expected flow becomes more concentrated. Thus, the output maps should be interpreted cautiously. Important areas for connectivity could be broad "sheet flow" linkages, or tight restricted corridors, depending on the priorities of decision makers.

Note the highest current density values tend to be found at the nodes themselves, which is an artifact of the way current flow is calculated. Post-processing the layers to remove this effect, before using the model results to set conservation priorities, is recommend as otherwise the node points will receive undue attention as connectivity routes (they represent more of the core habitats that need to be connected). Areas with little to no current flow can be interpreted as less important for connectivity, but only for the node pairs used. Circuitscape results are highly sensitive to the specific nodes used in the analysis. Users should examine node locations (available on request) before discounting a particular area of interest that appears to have low or zero current density. Consulting the Connectivity Analysis Toolkit results from the same project, which did not incorporate specific nodes and are therefore much less sensitive to the node selection process, may also be useful.

Not all species included in the overall index are found across the entire SALCC. For example, the eastern diamondback rattlesnake is absent from most of the piedmont and foothills. As a result, coastal areas where all species were potentially present receive a higher potential index score for connectivity than the piedmont areas outside of the range of the diamondback rattlesnake and pine snake.

If a smaller area is being considered (e.g. how to connect two specific core areas of habitat) then it would be more appropriate perhaps to use the single node pair output from Circuitscape corresponding to that area, instead of the regional cumulative map. The single pair results are available upon request. A box turtle model was attempted, but it proved to be computationally infeasible given the sheer number of nodes that would be involved across the study region. Complete details about the methodology of the project will be contained in the final report for the South Atlantic LCC, and in journal publications to follow. Users with urgent questions should send them to Ron Sutherland at ron@wildlandsnetwork.org.

Purpose

The connectivity result files from Circuitscape represent the adjusted cumulative future density flowing across the landscape for each of several species, at a 90-meter resolution across the South Atlantic Landscape Conservation Cooperative region. Rasters are classified using quantiles with 20 categories (each 5% of region) to integer scores from 1-20. 1 = lowest 5% of the landscape, 20= top 5% of landscape

Rights

Sutherland, R.W., Leonard, P., Carnes, R., Fedak, D., and Baldwin, R. Title: Terrestrial habitat connectivity models for the South Atlantic Landscape Conservation Cooperative. 2014. Wildlands Network
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Spatial Services

ArcGIS Mapping Service

WMS Service

Communities

  • LC MAP - Landscape Conservation Management and Analysis Portal
  • South Atlantic Landscape Conservation Cooperative

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Data source
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Sutherland, R.W., Leonard, P., Carnes, R., Fedak, D., and Baldwin, R. Title: Terrestrial habitat connectivity models for the South Atlantic Landscape Conservation Cooperative. Date: 2014 Published by: Wildlands Network

Additional Information

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