OVERVIEW

The NHESP Natural Communities datalayer consists of polygons that represent the extent of various natural communities of biodiversity conservation interest in Massachusetts. These polygons are based on records of natural communities maintained in the Natural Heritage & Endangered Species Program (NHESP) database. Program scientists classify and delineate natural community polygons by analyzing “on-the-ground” field data and available information about the landscape (particularly topographic maps and aerial photographs). All sites in the NHESP database have been visited by NHESP biologists or by other biologists who have submitted reports on community occurrences that NHESP biologists have reviewed and accepted.  Aquatic community types are not included.  The polygons are spatially represented at 1:25,000 or 1:24,000. The natural community types are from Swain, P.C. and J. B. Kearsley. 2001, Classification of the Natural Communities of Massachusetts, Version 1.3. Natural Heritage & Endangered Species Program.  The classification is available as PDF files or as paper copies purchased from NHESP. The draft classification names and describes 105 natural community types found in Massachusetts.

The datalayer is based on information on natural communities determined by NHESP to be of biodiversity conservation importance on a statewide basis. It is not intended to be part of a comprehensive vegetation map of the state. Additional verified natural community occurrences received during and after the preparation of this datalayer will be included in future iterations of the datalayer.

These polygons are not related to “Priority Habitat” or "Significant Habitat" as defined by the regulations of the Massachusetts Endangered Species Act (MESA). Natural Communities are not protected under the Massachusetts Endangered Species Act, but the rare species that may occur within some of these natural communities are protected by that law.

In ArcSDE the layer is named NATCOMM_POLY.

This datalayer was digitized primarily by NHESP scientists, usually through heads-up digitizing by the scientists themselves. Whenever possible, polygons were digitized to correspond to base features in either the digital topographic quadrangles, 1999 1:5,000 black and white orthophoto, or 2001 1:5,000-scale true color ortho imagery layers from MassGIS. Other base features used in determining boundaries included wetlands, hydrography, and elevation. Polygons for some records were initially drawn on paper 1:25,000 USGS topographic maps. 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 instances, a GPS point location was used as a reference when digitizing a natural community polygon.

For some community occurrences in eastern Massachusetts there was overlap between the communities for which NHESP has on-the-ground information and those identified in MassGIS’ ‘Priority Natural Vegetation Communities- April 2003’ datalayer. The community boundaries as identified by MassGIS’s aerial interpreter have been used if there were questions about the extent of the occurrence. For example, NHESP has data that an Inland Atlantic White Cedar Swamp community exists in the Hockomock Swamp, but the actual boundaries within the wetland were not established by the field work. Polygons showing the boundaries of the community type in the Priority Natural Vegetation Communities datalayer do delineate that specific community occurrence, and so were adopted as the NHESP polygon boundaries, as well. Several types of the “vegetation communities” include multiple types of NHESP natural communities which are difficult to differentiate without on-the-ground species occurrence information.

A very few occurrences of natural communities in the NHESP database (32 of the 693 now available, or 0.05%) are not included in this public datalayer due to the ecological sensitivity of the sites.

The polygon attribute table contains the following fields:

UNIQUE_ID		This reference number provides a unique identifier for each polygon.
COMMUN_NAME		This is the official name of the type of natural community as described in the Classification of the Natural Communities of Massachusetts (Swain and Kearsley, 2001).
COMMUN_RANK		Each type of natural community is assigned a rank, based on the ranking system developed for the Natural Heritage system by The Nature Conservancy and maintained by NatureServe. The state rank (Srank) reflects the rarity and threat within Massachusetts, with S1 being most uncommon and vulnerable in the state and S5 being demonstrably secure in Massachusetts. NHESP considers natural community types ranked S1-S3 to be priority for conservation protection. The state ranks (Srank) are: S1   Typically 5 or fewer occurrences, very few remaining individuals, acres, or miles of stream or especially vulnerable to extirpation in Massachusetts for other reasons. S2 Typically 6 - 20 occurrences, few remaining individuals, acres, or miles of stream or very vulnerable to extirpation in Massachusetts for other reasons. S3 Typically 21 - 100 occurrences, limited acreage, or miles of stream in Massachusetts. S4 Apparently secure in Massachusetts. S5 Demonstrably secure in Massachusetts
SPECIFIC_DESC		This is a brief statement on the specific occurrence of the community type represented by the polygon associated with the attribute table.
COMMUN_DESC		This is a brief, general description of the natural community type.
BNDRY_PREC		NHESP’s records are clear that the community named for each location exists there. However, on the ground, many natural community types grade into other types rather than change abruptly and thus have imprecise ‘boundaries’. In addition, the extent of occurrences of some communities, particularly types of large, matrix communities isn’t always established during field visits. The general precision of the delineation of each community type has been characterized as high, medium, or low. In most cases, precision increases when mapping community types associated with topographic features such as cliffs or kettlehole depressions, and decreases when mapping larger, less discreet community types such as different upland forest types.
COMMENTS		Some, but not all, polygons have a statement on management concerns associated with the community type in this field. Occasionally the comment is specific to that location, but usually the comments apply to the type more generally.
VERSION		Year in which the datalayer was last edited.

The legend that MUST accompany this datalayer on all maps is:
"NHESP Natural Communities, 2006 edition”

Please note that NHESP Natural Community polygons were designed for use at a regional or town scale. For accurate portrayal, the data should be displayed at scales of equal to or less than 1:25,000 (e.g., 1:30,000).

This datalayer is intended for conservation planning purposes only. It is NOT intended to be used for regulatory purposes. Other NHESP layers - Priority Habitats of Rare Species and Estimated Habitats of Wetland Wildlife - are designed for regulatory use.  They are produced in the Natural Heritage Atlas, and are available from MassGIS at http://www.mass.gov/mgis/prihab.htm and http://www.mass.gov/mgis/esthab.htm.

The NHESP database is continuously updated as occurrence records are added, modified or deleted. Those changes will be incorporated into the natural community GIS datalayer periodically, with a date in the public datalayer name indicating the most recent version.

Questions about biological aspects of the NHESP Natural Communities datalayer should be directed to NHESP at 508-792-7270 x 160.

The full text of Swain & Kearsley’s Classification of the Natural Communities of Massachusetts Version 1.3. See http://www.mass.gov/dfwele/dfw/nhesp/natural_communities/natural_community_classification.htm for the current classification documents.

Fact sheets for some of the natural communities are available on the NHESP website at  www.nhesp.org . A few other natural community fact sheets are available by request from the NHESP, by calling 508-792-7270 x 200.

Last Updated 4/17/2009
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