An extensive tabular database is maintained by the Natural
Heritage Program. Other data that can be accessed include
element occurrence identification number.
Supplemental materials are also available that indicate the
state, national, and global status of the rare plants and
animals of North Carolina. These publications are available
from the NHP and are helpful in understanding each natural
heritage record. (SEE CROSS REFERENCES)
NATURAL HERITAGE PROGRAM DATA
The Natural Heritage Program is the state's most comprehensive
source of information on rare and endangered animals and
plants, and exemplary natural communities, known collectively
as "elements of natural diversity." Since 1976, the program
has systematically gathered information on the occurrence and
the status of the state's ecological resources. The inventory
consists of information compiled from a broad range of sources
including herbarium and museum collections, published and
unpublished literature, and field surveys by volunteers,
contracted workers, and staff. Information from and
interpretation of this database for specific sites is
available from the Natural Heritage Program. This is generally
the preferred method of getting information on elements of
natural diversity. The geographic content of the Natural
Heritage Program element occurrence database has also been
incorporated into the NC OneMap database where it can be combined with
other geographic data for planning and analysis. Users of the
data must, however, be aware of the nature and limitations of
the data.
LIMITATIONS OF DATA
The element occurrence database contains data from a variety
of sources, which vary in the quality of their locational
information. Some centroid points may be as much as several
miles off, though most are closer and many are exact to within
one or two seconds of latitude or longitude.
The precision of record is indicated in the Natural Heritage
Program databases. Because of uncertainty about the precision
and accuracy of source data, and because the aerial extent of
occurrences is not indicated on CGIA maps, occurrences anywhere
within several miles of a site of interest should be regarded as
indicating the need for more information. Probability of effects
by a project depends on the actual location and extent of the
element occurrence, on the nature of the species or community,
and on the nature of the action being considered. Interpretation
of potential effects should be done only by biologists familiar
with the element, with the best locational information available.
LIMITATIONS OF ABSENCE OF DATA
Although the Natural Heritage Program has conducted numerous
biological inventories and has assembled as much of the
secondary source data as possible, the majority of the
state has never been systematically surveyed for rare species
or natural communities. In addition, negative surveys are
seldom reported to the Natural Heritage Program and are not
recorded. The database reflects only locations where an element
was once known to occur. It does not distinguish between areas
known to have no elements and those that have not been checked.
The absence of element location cannot be taken as an indication
of absence of elements or of ecological concerns. Natural
Heritage Program biologists are often able to give indications
of the potential for concern in unsurveyed areas.
DATA CURRENCY
The Natural Heritage Program databases are continually updated
as new information is acquired. The locational database at
CGIA is updated as needed for applications. Users should
determine the date of the last update and, if necessary,
see that an update is done prior to their application being run.
All printed maps from the GIS should be dated. Depending on
activity in a given area, a map may quickly become outdated, or
may remain current for several years. It is not possible to set
a specific expiration date on maps; however, data more than six
months old should not be depended on without checking with the
Natural Heritage Program.
Only a small portion of the rare species and community locations
are monitored on a regular basis. Information in the Natural
Heritage Program database represents the occurrence at the last
time it was observed. The date of last observation is given in
the Natural Heritage Program database but is not included in
the NC OneMap datalayer. Records are kept in the database until
the destruction of an occurrence is confirmed. Thus, some of
the records are likely to represent locations where an element
has not been seen in many years and may no longer be present.
ADDITIONAL INFORMATION
Additional information about databases, elements of natural
diversity, and user services is available from the Natural
Heritage Program. The basic data are "public records" and
are available for inspection on request for reasonable purposes.
Beginning with the May 16, 2008 version quite a few low precision,
county-level element occurrences were replaced with more precise
locations. There was a large drop in acreage from the previous
version, but loss of acreage in the NHEO layer should not be
interpreted as loss of habitat. The relatively few low precision
records in the coverage will dominate the acreage total, and any
changes in these will obscure any acreage trends. The trend of
replacing low precision records with higher precision will continue
in future versions. That doesn't guarantee that the number of low
precision records will continually go down, though, since NHP may
start tracking a new species which has only poor data initially.
Revisions and updates to this layer include:
9.) NHEO layer updated May 28, 2009.
8.) NHEO layer updated Janurary 8, 2009.
7.) NHEO layer updated May 16, 2008.
6.) NHEO layer updated February 1, 2008. Data are now stored in one dataset. Points and lines are buffered and put into this polygon dataset.
5.) NHEO layer updated November 27, 2007.
4.) NHEO layer updated February 27, 2007.
3.) NHEO layer updated August 16, 2006.
2.) NHEO layer updated December 2005.
1.) NHEO layer updated September 7, 2005.
Data are now stored in three datasets: lines, polygons, and points.