Intact Habitat Cores

This indicator represents the size of large, unfragmented patches of natural habitat. It identifies minimally disturbed natural areas at least 100 acres in size and greater than 200 meters wide. This indicator originates from Esri’s green infrastructure data.

Reason for Selection

Large areas of intact natural habitat are favorable for conservation of numerous species, including reptiles and amphibians, birds, and large mammals. The Esri Green Infrastructure data covers the entire United States and has been used in other broad-scale conservation planning efforts, so using this existing data helps align the Blueprint with other conservation efforts and reduce duplication of effort. We chose to use “Core Size (acres)” as the metric for this indicator. Other evaluation attributes included in this index, such as the default “Core Score”, were less suitable because they were calculated using inputs that are duplicative of other indicators.

Input Data

• Esri Green Infrastructure Data: Intact habitat cores by state, core size (acres)

  We downloaded this dataset by state from arcgis.com. The Esri Green Infrastructure website provides more information about these data, access to the models utilized to generate them, and additional online applications for green infrastructure planning. More information about the intact habitat cores is available here and in this FAQs document.

  Esri’s description of the core size metric states: “Cores were derived from the 2011 National Land Cover dataset. The ‘natural’ land cover classes were included and all ‘developed’ and ‘agricultural’ classes including crop, hay and pasture lands were excluded. The resulting cores were tested for size and width requirements (at least 100 acres in size and greater than 200 m) and then converted into unique polygons.”

• Base Blueprint 2022 extent

Mapping Steps

• Create a new feature class by merging all the state-level “Intact Habitat Cores (March 2017)” polygon feature classes that cover the Southeast region using the ArcPy Merge function.
• Delete identical polygons from the merged feature class using the ArcPy Delete Identical function. This removes duplicate polygons that span state boundaries and are included in multiple state layers.
• Convert the polygon to a raster using the ArcPy Polygon to Raster function using the value field of “Acres”. This results in a raster dataset with 30 m cell size with values based on the “Core Size (acres)” field calculated by the Esri Green Infrastructure Data group.
• Change NoData values (pixels not covered by an intact habitat core) to 0.
• Reclassify the above raster into 4 classes, seen in the final indicator values below.
• As a final step, clip to the spatial extent of Base Blueprint 2022.

Note: For more details on the mapping steps, code used to create this layer is available in the Southeast Blueprint 2022 Data Download under BlueprintInputs > BaseBlueprint2022 > 6_Code.

Final Indicator Values

Indicator values are assigned as follows:

• 3 = Large core (>10,000 acres)
• 2 = Medium core (>1,000-10,000 acres)
• 1 = Small core (>100–1,000 acres)
• 0 = Not a core

Known Issues

• This indicator is based on the 2011 NLCD, not the more recent 2019 NLCD. The data creator (Esri) plans to update the source data to more recent landcover next year. Esri has also shared the scripts and input data used to create this layer, which may also help update this indicator in the future.
• Even small dirt roads serve as hard boundaries for habitat cores. While this makes sense for some species, the effective size of the patch for some more mobile animals is likely underestimated.
• Waterbodies like reservoirs are also considered part of habitat cores, so this layer likely overestimates the effective size of the habitat core for most species.

Disclaimer: Comparing with Older Indicator Versions There are numerous problems with using Southeast Blueprint indicators for change analysis. Please consult Blueprint staff if you would like to do this (email hilary_morris@fws.gov).

Literature Cited

Esri Green Infrastructure Center, Inc. 2017. Esri Green Infrastructure Data Description. [http://www.arcgis.com/sharing/rest/content/items/5561da06127d48a982d6b91929f29666/data].