OVERVIEW

Core Habitat is one of two datalayers resulting from the BioMap biodiversity mapping project.The Core Habitat layer depicts the most viable habitat for rare species and natural communities in Massachusetts. Using a variety of data sources, primarily field data, ancillary literature, and color-infrared aerial photographs, Natural Heritage and Endangered Species Program scientists delineated Core Habitat polygons. The polygons were "heads-up" digitized (drawn on screen) by the scientists themselves, in Arcview. Whenever possible, polygons were digitized to correspond to base features in either the digital topographic quadrangles or 1:5,000 black and white orthophoto layers from MassGIS. Other base features used in determining boundaries included wetlands, hydrography, and elevation. Habitat for some invertebrate and most mammal species was initially drawn on paper 1:25,000 USGS topographic maps with other features, such as verified rare species and potential vernal pool locations, also shown. When heads-up digitizing was used, polygons were digitized to a scale of 1:25,000 or larger (i.e. 1: 5,000). In some cases, a GPS point location taken by program scientists was used as a reference when digitizing a core habitat polygon.

This single statewide layer is stored in the State library; its coverage and layer name is BIOCORE. In ArcSDE the layer is named BIOCORE_POLY.

Polygons were digitized for individual species, groups of species and natural communities. Core Habitat for plant species consisted primarily of buffered point locations with developed areas clipped out. Core Habitat polygons were then checked to flag areas where recent development might impact the polygon boundaries. These areas were excised from Core Habitat where appropriate. The final linework for individual species and natural community polygons was merged into a single coverage. This "super set" of all overlapping Core Habitat polygons was then aggregated using a ‘union’ process and built as a polygon coverage in ArcInfo.

The polygon attribute table contains the following items:
 

BIOCORID		16		16		C		NHESP unique identifier
COREPOLY		1		1		I		1 = Biocore polygons  0 = "interior" polygons (not Biocore)

As outlined above, a Core Habitat polygon may consist of many individual species or natural community polygons- this individual species information is not identified in the Core Habitat layer.

• The legend that MUST accompany this datalayer on ALL maps is:
"NHESP BioMap Core Habitat".
• Please note that Core Habitat polygons were designed for use at a regional or town scale. For accurate portrayal, the data should be displayed at scales of less than 1:25,000 (e.g., 1:30,000).
• This datalayer is intended for conservation planning purposes only. It should not be used for regulatory purposes. The NHESP layers designed for regulatory use are produced in the Natural Heritage Atlas.

In June 2002 a few very small natural commuities were removed. The Natural Heritage Program is currently revisiting the attributing of polygons; this is the only maintenance of this datalayer currently envisioned. Questions about this datalayer should be directed to NHESP at 508-792-7270 x300.

This layer is one of two BioMap layers from NHESP. Also see the NHESP BioMap Supporting Natural Landscape datalayer description.

• The BioMap Supporting Natural Landscape datalayer was designed to place Core Habitat polygons within a functional landscape. See the metadata for that datalayer for more detail.
• The Natural Heritage and Endangered Species Program has published two reports:
• ‘BioMap: Guiding Land Conservation for Biodiversity in Massachusetts’, a full color report on the BioMap project
• ‘The BioMap Technical Report’, which presents much greater technical detail on the methodology used to develop the BioMap, along with the scientific basis for these methods.
See http://www.state.ma.us/dfwele/dfw/nhesp/nhbiomap.htm for information on receiving these two reports for more detail on the criteria and methodology for selecting and delineating Core Habitats.

Last Updated 6/8/2004
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