These data represent intact habitat cores. Habitat cores are minimally disturbed natural areas at least 100 acres in size and greater than 200 meters wide. These data are intended to identify natural assets and support green infrastructure planning at the national, regional, and local scales.

This is one of five companion green infrastructure datasets that if used together should have corresponding date-based suffixes (YYYYMMDD). The corresponding layer names are: HabitatCores, LCPConnectors, Fragments, CostSurf and BetwnCentrality
<DIV STYLE="text-align:Left;"><DIV><DIV><P STYLE="margin:0 0 18 0;"><SPAN>Following a methodology outlined by the </SPAN><A href="http://www.gicinc.org/index.htm"><SPAN><SPAN>Green Infrastructure Center</SPAN></SPAN></A><SPAN><SPAN> Inc., Esri staff created a national intact habitat cores database for the lower 48 United States. These data were generated using 2011 National Land Cover Data. Cores were derived from all “natural” land cover classes and excluded all “developed” and “agricultural” classes including crop, hay and pasture lands. The resulting cores were tested for size and width requirements (at least 100 acres in size and greater than 200 meters) and then converted into unique polygons. This process resulted in the generation of over 550,000 intact habitat cores. </SPAN></SPAN></P><P STYLE="margin:0 0 0 0;"><SPAN><SPAN>These polygons were then overlaid with a diverse assortment of physiographic, biologic and hydrographic layers to populate each core with attributes (53 in total) related to the landscape characteristics found within. These data were also compiled to compute a “core quality index”, or score related to the perceived ecological value of each core, to provide users with additional insight related to the importance of each core when compared to all others. The source data used to derive this attribution is as follows:</SPAN></SPAN></P><P /><P STYLE="margin:0 0 0 0;"><SPAN STYLE="font-weight:bold;"><SPAN>Source data</SPAN></SPAN><SPAN><SPAN>:</SPAN></SPAN></P><P STYLE="margin:0 0 0 0;"><SPAN STYLE="font-weight:bold;"><SPAN>Number of endemic species:</SPAN></SPAN><SPAN><SPAN>(Mammals, Fish, Reptiles, Amphibians, Trees) Jenkins, Clinton N., et. al, (April 21, 2015) </SPAN></SPAN><SPAN STYLE="font-style:italic;"><SPAN>US protected lands mismatch biodiversity priorities</SPAN></SPAN><SPAN><SPAN>, PNAS vol.112, no. 16, </SPAN></SPAN><A href="http://www.pnas.org/cgi/doi/10.1073/pnas.1418034112"><SPAN><SPAN>www.pnas.org/cgi/doi/10.1073/pnas.1418034112</SPAN></SPAN></A><SPAN><SPAN>)</SPAN></SPAN></P><P /><P STYLE="margin:0 0 0 0;"><SPAN STYLE="font-weight:bold;"><SPAN>Priority Index areas: Endemic species, small home range size and low protection status</SPAN></SPAN><SPAN><SPAN>. Jenkins, Clinton N., et. al, (April 21, 2015) </SPAN></SPAN><SPAN STYLE="font-style:italic;"><SPAN>US protected lands mismatch biodiversity priorities</SPAN></SPAN><SPAN><SPAN>, PNAS vol.112, no. 16, </SPAN></SPAN><A href="http://www.pnas.org/cgi/doi/10.1073/pnas.1418034112"><SPAN><SPAN>www.pnas.org/cgi/doi/10.1073/pnas.1418034112</SPAN></SPAN></A><SPAN><SPAN>)</SPAN></SPAN></P><P /><P STYLE="margin:0 0 0 0;"><SPAN STYLE="font-weight:bold;"><SPAN>Unique ecological systems:</SPAN></SPAN><SPAN><SPAN>Based upon work by Aycrigg, Jocelyn L, et. al. (2013) Representation of Ecological Systems within the Protected Areas Network of the Continental United States. PLos One 8(1):e54689). New data constructed by Esri staff, using TNC Ecological Regions as summary areas.</SPAN></SPAN></P><P /><P STYLE="margin:0 0 0 0;"><SPAN STYLE="font-weight:bold;"><SPAN>Ecologically relevant landforms:</SPAN></SPAN><SPAN /><SPAN /><SPAN><SPAN>Theobald DM, Harrison-Atlas D, Monahan WB, Albano CM (2015) </SPAN></SPAN><SPAN STYLE="font-style:italic;"><SPAN>Ecologically-Relevant Maps of Landforms and Physiographic Diversity for Climate Adaptation Planning.</SPAN></SPAN><SPAN><SPAN>PLoS ONE 10(12): e0143619. doi:10.1371/journal.pone.0143619</SPAN></SPAN><A href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0143619"><SPAN><SPAN>http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0143619</SPAN></SPAN></A></P><P /><P STYLE="margin:0 0 0 0;"><SPAN STYLE="font-weight:bold;"><SPAN>Local Landforms:</SPAN></SPAN><SPAN><SPAN>Produced 3/2016 by Deniz Karagulle and Charlie Frye, Esri, 30 m* resolution. </SPAN></SPAN></P><P STYLE="margin:0 0 0 0;"><SPAN><SPAN>"Improved Hammond’s Landform Classification and Method for Global 250-m Elevation Data" by Karagulle, Deniz; Frye, Charlie; Sayre, Roger; Breyer, Sean; Aniello, Peter; Vaughan, Randy; Wright, Dawn, In Review, Transactions in GIS.</SPAN></SPAN></P><P STYLE="margin:0 0 0 0;"><SPAN><SPAN>*The neighborhood window was scaled from the 250-meter method described in the paper to 30-meter data in the U.S.</SPAN></SPAN></P><P /><P STYLE="margin:0 0 0 0;"><SPAN STYLE="font-weight:bold;"><SPAN>Ecological Land Units: </SPAN></SPAN><SPAN><SPAN>Sayre, R., J. Dangermond, C. Frye, R. Vaughan, P. Aniello, S. Breyer, D. Cribbs, D. Hopkins, R. Nauman, W. Derrenbacher, D. Wright, C. Brown, C. Convis, J. Smith, L. Benson, D. Paco VanSistine, H. Warner, J. Cress, J. Danielson, S. Hamann, T. Cecere, A. Reddy, D. Burton, A. Grosse, D. True, M. Metzger, J. Hartmann, N. Moosdorf, H. Dürr, M. Paganini, P. DeFourny, O. Arino, S. Maynard, M. Anderson, and P. Comer. 2014. A New Map of Global Ecological Land Units — An Ecophysiographic Stratification Approach. Washington, DC: Association of American Geographers. 46 pages </SPAN></SPAN><A href="http://www.aag.org/cs/global_ecosystems"><SPAN><SPAN>http://www.aag.org/cs/global_ecosystems</SPAN></SPAN></A><SPAN><SPAN>. 2015 updated data accessed 3/2016, 250 m resolution.</SPAN></SPAN></P><P /><P STYLE="margin:0 0 0 0;"><SPAN STYLE="font-weight:bold;"><SPAN>National Elevation Dataset:</SPAN></SPAN><SPAN><SPAN>USGS, 30 m resolution, </SPAN></SPAN><A href="http://viewer.nationalmap.gov/launch/"><SPAN><SPAN>http://viewer.nationalmap.gov/launch/</SPAN></SPAN></A></P><P /><P STYLE="margin:0 0 0 0;"><SPAN STYLE="font-weight:bold;"><SPAN>NWI – National Wetlands Inventory:</SPAN></SPAN><SPAN /><SPAN /><SPAN><SPAN>Classification of Wetlands and Deepwater Habitats of the United States. U.S. Department of the Interior, Fish and Wildlife Service, Washington, DC. FWS/OBS-79/31, U.S. Fish and Wildlife Service, Division of Habitat and Resource Conservation (prepared 10/2015)</SPAN></SPAN></P><P /><P STYLE="margin:0 0 0 0;"><SPAN STYLE="font-weight:bold;"><SPAN>NLCD 2011 – National LandCover Database 2011:</SPAN></SPAN><SPAN /><SPAN /><A href="http://www.mrlc.gov/nlcd2011.php"><SPAN><SPAN>http://www.mrlc.gov/nlcd2011.php</SPAN></SPAN></A><SPAN><SPAN>(downloaded 1/2016) </SPAN></SPAN><SPAN><SPAN>Homer, C.G., et. al. 2015,</SPAN></SPAN><A href="http://bit.ly/1K7WjO3"><SPAN><SPAN>Completion of the 2011 National Land Cover Database for the conterminous United States-Representing a decade of land cover change information</SPAN></SPAN></A><SPAN><SPAN>. </SPAN></SPAN><SPAN STYLE="font-style:italic;"><SPAN>Photogrammetric Engineering and Remote Sensing</SPAN></SPAN><SPAN><SPAN>, v. 81, no. 5, p. 345-354 </SPAN></SPAN></P><P /><P STYLE="margin:0 0 0 0;"><SPAN STYLE="font-weight:bold;"><SPAN>NHDPlusV2:</SPAN></SPAN><SPAN /><SPAN /><A href="https://www.epa.gov/waterdata/nhdplus-national-hydrography-dataset-plus"><SPAN><SPAN>https://www.epa.gov/waterdata/nhdplus-national-hydrography-dataset-plus</SPAN></SPAN></A><SPAN /><SPAN /><SPAN><SPAN>Received from Charlie Frye, Esri 3/2016. Produced by the EPA with support from the USGS.</SPAN></SPAN></P><P /><P STYLE="margin:0 0 0 0;"><SPAN STYLE="font-weight:bold;"><SPAN>gSSURGO:</SPAN></SPAN><SPAN /><SPAN /><SPAN><SPAN>Soil Survey Staff. Gridded Soil Survey Geographic Database for the Conterminous United States. Natural Resources Conservation Service, United States Department of Agriculture. Available online at </SPAN></SPAN><A href="http://gdg.sc.egov.usda.gov/"><SPAN><SPAN>http://gdg.sc.egov.usda.gov/</SPAN></SPAN></A><SPAN><SPAN>. </SPAN></SPAN><SPAN><SPAN>Accessed 3/2016, 30 m resolution</SPAN></SPAN></P><P /><P STYLE="margin:0 0 0 0;"><SPAN STYLE="font-weight:bold;"><SPAN>SSurgo:</SPAN></SPAN><SPAN /><SPAN /><SPAN><SPAN>Soil Survey Staff, Natural Resources Conservation Service, United States Department of Agriculture. Web Soil Survey. Available online at </SPAN></SPAN><A href="http://websoilsurvey.nrcs.usda.gov/"><SPAN><SPAN>http://websoilsurvey.nrcs.usda.gov/</SPAN></SPAN></A><SPAN><SPAN>. Accessed 3/2016</SPAN></SPAN></P><P /><P STYLE="margin:0 0 0 0;"><SPAN STYLE="font-weight:bold;"><SPAN>GAP Level 3 Ecological System Boundaries:</SPAN></SPAN><SPAN /><SPAN /><A href="http://gapanalysis.usgs.gov/gaplandcover/data/download/"><SPAN><SPAN>http://gapanalysis.usgs.gov/gaplandcover/data/download/</SPAN></SPAN></A></P><P STYLE="margin:0 0 0 0;"><SPAN><SPAN>(downloaded 4/ 2016) </SPAN></SPAN></P><P /><P STYLE="margin:0 0 0 0;"><SPAN STYLE="font-weight:bold;"><SPAN>NOAA CCAP </SPAN></SPAN><SPAN STYLE="font-weight:bold;">Coastal Change Analysis Program Regional Land Cover and Change:</SPAN></P><P STYLE="margin:0 0 0 0;"><SPAN /><A href="https://coast.noaa.gov/ccapftp/"><SPAN STYLE="font-weight:bold;"><SPAN>https://coast.noaa.gov/ccapftp/#/</SPAN></SPAN></A><SPAN /></P><P STYLE="margin:0 0 0 0;"><SPAN>Description: </SPAN><A href="https://coast.noaa.gov/dataregistry/search/collection/info/ccapregional"><SPAN><SPAN>https://coast.noaa.gov/dataregistry/search/collection/info/ccapregional</SPAN></SPAN></A><SPAN /></P><P STYLE="margin:0 0 0 0;"><SPAN>30 m resolution, 2010 edition of data (downloaded by state 3/2016)</SPAN></P><P STYLE="margin:0 0 0 0;"><SPAN /></P><P STYLE="margin:0 0 0 0;"><SPAN /></P><P STYLE="margin:0 0 0 0;"><SPAN STYLE="font-weight:bold;"><SPAN>NHD USGS National Hydrography Dataset:</SPAN></SPAN><SPAN /><SPAN /><A href="http://nhd.usgs.gov/data.html"><SPAN><SPAN>http://nhd.usgs.gov/data.html</SPAN></SPAN></A><SPAN /><SPAN /></P><P /><P STYLE="margin:0 0 0 0;"><SPAN STYLE="font-weight:bold;"><SPAN>TNC Terrestrial Ecoregions:</SPAN></SPAN><SPAN /><SPAN /><A href="http://maps.tnc.org/gis_data.html"><SPAN><SPAN>http://maps.tnc.org/gis_data.html#TNClands</SPAN></SPAN></A><SPAN><SPAN>(downloaded 3/2016)</SPAN></SPAN></P><P /><P><SPAN STYLE="font-weight:bold;"><SPAN>2015 LCC Network Areas:</SPAN></SPAN><SPAN /><SPAN /><A href="https://www.sciencebase.gov/catalog/item/55b943ade4b09a3b01b65d78"><SPAN><SPAN>https://www.sciencebase.gov/catalog/item/55b943ade4b09a3b01b65d78</SPAN></SPAN></A></P><P /><P /><P STYLE="font-weight:bold;margin:0 0 0 0;"><SPAN><SPAN>Detailed Description of the Core Quality Index Methodology:</SPAN></SPAN></P><P STYLE="margin:0 0 0 0;"><SPAN><SPAN>The creation of a national core quality index was a challenging undertaking given the extreme heterogeneity of ecosystem conditions across the United States. As a result, 9 separate index scores were generated for each core, each placing varying weights on landscape characteristics of regional or local significance. This was done to account for variation across the U.S. and to provide users with additional flexibility in accommodating regional or local environmental priorities.</SPAN></SPAN></P><P /><P STYLE="margin:0 0 0 0;"><SPAN><SPAN>Two general approaches were used in developing the core quality index values. The first, Default Weights, uses core size as the primary determinant of quality, following the guidance of the Green Infrastructure Center’s scoring approach developed for the southeastern US. The second, Bio-Weights, puts more emphasis on characteristics associated with bio-diversity and uniqueness of ecosystem types and de-emphasizes slightly the importance of core size. This alternative was developed to compensate for the very large intact core habitat areas in the west and southwest which also have comparatively low biodiversity values.</SPAN></SPAN></P><P /><P STYLE="font-weight:bold;margin:0 0 0 0;"><SPAN><SPAN>Scoring values:</SPAN></SPAN></P><P /><P STYLE="font-weight:bold;margin:0 0 0 0;"><SPAN><SPAN>Default Weights</SPAN></SPAN></P><P STYLE="margin:0 0 0 0;"><SPAN><SPAN>0.4, # Acres</SPAN></SPAN></P><P STYLE="margin:0 0 0 0;"><SPAN /><SPAN /><SPAN /><SPAN><SPAN>0.1, # Thickness</SPAN></SPAN><SPAN /><SPAN /><SPAN /></P><P STYLE="margin:0 0 0 0;"><SPAN>0.05, # Topographic Diversity (Standard Deviation)</SPAN><SPAN /><SPAN /><SPAN /></P><P STYLE="margin:0 0 0 0;"><SPAN><SPAN>0.1, # Biodiversity Priority Index (Species Richness in GIC original version)</SPAN></SPAN></P><P STYLE="margin:0 0 0 0;"><SPAN /><SPAN /><SPAN /><SPAN><SPAN>0.05, # Percentage Wetland Cover</SPAN></SPAN><SPAN /><SPAN /><SPAN /></P><P STYLE="margin:0 0 0 0;"><SPAN><SPAN>0.03, # Ecological Land Unit – Shannon-Weaver Index (Soil Variety in GIC original version)</SPAN></SPAN></P><P STYLE="margin:0 0 0 0;"><SPAN /><SPAN /><SPAN /><SPAN><SPAN>0.02, # Compactness Ratio (Area relative to the area of a circle with the same perimeter length)</SPAN></SPAN></P><P STYLE="margin:0 0 0 0;"><SPAN><SPAN>0.1, # Stream Density (Linear Feet/Acre)</SPAN></SPAN></P><P STYLE="margin:0 0 0 0;"><SPAN /><SPAN /><SPAN /><SPAN><SPAN>0.05, # Ecological System Redundancy (Rare/Threatened/Endangered Species Abundance (Number of occurrences) in GIC original version) </SPAN></SPAN><SPAN /><SPAN /><SPAN /></P><P STYLE="margin:0 0 0 0;"><SPAN><SPAN>0.1, # Endemic Species Max (Rare/Threatened/Endangered Species Abundance (Number of unique species in a core) in GIC original version) </SPAN></SPAN></P><P /><P STYLE="font-weight:bold;margin:0 0 0 0;"><SPAN><SPAN>Bio-Weights</SPAN></SPAN></P><P STYLE="margin:0 0 0 0;"><SPAN><SPAN>0.2, # Acres</SPAN></SPAN></P><P STYLE="margin:0 0 0 0;"><SPAN /><SPAN /><SPAN /><SPAN><SPAN>0.1, # Thickness</SPAN></SPAN><SPAN /><SPAN /><SPAN /></P><P STYLE="margin:0 0 0 0;"><SPAN><SPAN>0.05, # Topographic Diversity (Standard Deviation)</SPAN></SPAN></P><P STYLE="margin:0 0 0 0;"><SPAN /><SPAN /><SPAN /><SPAN><SPAN>0.25, # Biodiversity Priority Index (Species Richness in GIC original version)</SPAN></SPAN><SPAN /><SPAN /><SPAN /></P><P STYLE="margin:0 0 0 0;"><SPAN><SPAN>0.05, # Percentage Wetland Cover</SPAN></SPAN><SPAN /><SPAN /><SPAN /></P><P STYLE="margin:0 0 0 0;"><SPAN><SPAN>0.03, # Ecological Land Unit – Shannon-Weaver Index (Soil Variety in GIC original version)</SPAN></SPAN></P><P STYLE="margin:0 0 0 0;"><SPAN /><SPAN /><SPAN /><SPAN><SPAN>0.02, # Compactness Ratio (Area Relative To The Area Of A Circle With The Same Perimeter Length)</SPAN></SPAN></P><P STYLE="margin:0 0 0 0;"><SPAN /><SPAN /><SPAN /><SPAN><SPAN>0.1, # Stream Density (Linear Feet/Acre)</SPAN></SPAN></P><P STYLE="margin:0 0 0 0;"><SPAN /><SPAN /><SPAN /><SPAN><SPAN>0.1, # Ecological System Redundancy (Rare/Threatened/Endangered Species Abundance (Number of occurrences) in GIC original version) </SPAN></SPAN><SPAN /><SPAN /><SPAN /></P><P STYLE="margin:0 0 0 0;"><SPAN><SPAN>0.1, # Endemic Species Max (Rare/Threatened/Endangered Species Diversity (Number of unique species in a core) in GIC original version) </SPAN></SPAN></P><P /><P STYLE="margin:0 0 0 0;"><SPAN><SPAN>Scripts for constructing local cores and scoring them using the Green Infrastructure Center’s methodology are available on </SPAN></SPAN><A href="http://www.esri.com/about-esri/greeninfrastructure"><SPAN><SPAN>http://www.esri.com/about-esri/greeninfrastructure</SPAN></SPAN></A><SPAN /><SPAN /></P></DIV></DIV></DIV>
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