Congaree Swamp National Monument Spatial Vegetation Data; Cover Type/Association Level of the National Vegetation Classification System

The National Park Service (NPS), in conjunction with the Biological Resources
Division (BRD) of the U.S. Geological Survey (USGS), has implemented a program
to "develop a uniform hierarchical vegetation methodology" at a national level.
The program will also create a geographic information system (GIS) database for
the parks under its management. The purpose of the data is to document the
state of vegetation within the NPS service area during the 1990's, thereby
providing a baseline study for further analysis at the Regional or Service-wide
level. The vegetation units of this map were determined through stereoscopic
interpretation of aerial photographs supported by field sampling and ecological
analysis. The vegetation boundaries were identified on the photographs by means
of the photographic signatures and collateral information on slope, hydrology,
geography, and vegetation in accordance with the Standardized National
Vegetation Classification System (October 1995). The mapped vegetation reflects
conditions that existed during the specific year and season that the aerial
photographs were taken (April, 1996). There is an inherent margin of error in
the use of aerial photography for vegetation delineation and classification.

The purpose of this spatial data is to provide the National Park Service the
necessary tools to manage the natural resources within this park system.
Several parks, representing different regions, environmental conditions, and
vegetation types, were chosen by BRD to be part of the prototype phase of the
program. The initial goal of the prototype phase is to "develop, test, refine,
and finalize the standards and protocols" to be used during the production
phase of the project. This includes the development of a standardized
vegetation classification system for each park and the establishment of
photointerpretation, field, and accuracy assessment procedures. Congaree Swamp
National Monument was designated as one of the prototype parks. Congaree Swamp
National Monument, established in 1976, was designated as one of the prototypes
within the National Park System. The park contains approximately 22,200 acres
(34 square miles). Congaree Swamp National Monument is located approximately 15
miles southeast of Columbia, the state capitol of South Carolina. The Congaree
River, draining over 8,000 square miles of Piedmont land to the northwest,
forms the southern border.

On June 30, 1983, Congaree Swamp National Monument became an International
Biosphere Reserve. Congaree is noted for containing one of the last significant
stands of old growth bottomland hardwood forest, over 11,000 acres in all. The
Monument contains over 90 species of trees, 16 of which hold state records for
size. Included in this list of records is a national record sweet gum with a
basal circumference of nearly 20 feet.

Congaree Swamp National Monument is located approximately 15 miles southeast of
Columbia, the state capitol of South Carolina. Old Bluff Highway (old Highway
48) lies just north of the Monument boundary. The eastern boundary is located
just northwest of the confluence of the Congaree and Wateree Rivers. The
Monument extends west to where Cedar Creek and Myers Creek join.

The normal process in vegetation mapping is to conduct an initial field
reconnaissance, map the vegetation units through photointerpretation, and then
conduct a field verification. The field reconnaissance visit serves two major
functions. First, the photointerpreter keys the signature on the aerial photos
to the vegetation on the ground at each signature site. Second, the
photointerpreter becomes familiar with the flora, vegetation communities and
local ecology that occur in the study area. Park and/or TNC field biologists
that are familiar with the local vegetation and ecology of the park are present
to help the photointerpreter understand these elements and their relationship
with the geography of the park. Upon completion of the field reconnaissance,
photo interpreters delineate vegetation units on mylar that overlay the 9x9
aerial photos. This effort is conducted in accordance with the TNC vegetation
classification and criteria for defining each community or alliance. The
initial mapping is then followed by a field verification session, whose purpose
is to verify that the vegetation units were mapped correctly. Any PI related
questions are also addressed during the visit. The vegetation mapping at
Congaree Swamp National Monument in general followed the normal mapping
procedure as described in the above paragraph with two major exceptions: 1)
Preliminary delineations for most of the park, including a set of Focused
Transect overlays that were labeled with an initial PI signature commenced
prior to the field reconnaissance visit. 2) A TNC classification did not exist
at the time the initial delineations began. TNC ecologist and AIS photo
interpreters worked together to develop an interim signature key which
addressed what was known at the time. At that time, no comprehensive study
containing plot data was available to create an interim classification.

From the onset of the Vegetation Inventory and Mapping Program, a standardized
program-wide mapping criteria has been used. The mapping criteria contains a
set of documented working decision rules used to facilitate the maintenance of
accuracy and consistency of the photointerpretation. This criteria assists the
user in understanding the characteristics, definition and context for each
vegetation community. The mapping criteria for Congaree Swamp National Monument
was composed of four parts: The standardized program-wide general mapping
criteria A park specific mapping criteria A working photo signature key The TNC
classification, key and descriptions The following sections detail the mapping
criteria used during the photointerpretation of Congaree Swamp. General Mapping
Criteria The mapping criteria at Congaree Swamp are a modified version from
previously mapped parks. The criteria differs primarily in that the height and
density variables were not mapped at Congaree Swamp. Instead, two additional
variables were addressed: pre-hurricane Hugo community types and areas of pine
that have been logged since the time of the 1976 aerial photography. These two
categories will be addressed in the Park Specific Mapping Criteria section of
this report. Since forest densities within the Monument are nearly always
greater than 60%, it served little or no purpose in addressing this element as
a separate attribute in the database. In addition it was also determined that
height categories are extremely difficult to map in the Monument due to
variability of the tree emergent layer, and lack of any significant reference
points that help in determining canopy heights. Alliance / Community
Associations The assignment of alliance and community association to the
vegetation is based on criteria formulated by the field effort and
classification development. In the case of Congaree Swamp National Monument,
TNC provided AIS with a tentative community classification in April 1998. A
final vegetation classification, key, and descriptions of each alliance and
community, was provided in October 1998. In addition, TNC provided AIS with
detailed plot data showing how the communities were developed in the Monument.

The information for the metadata came from
"http://biology.usgs.gov/npsveg/cosw/metacoswspatial.html" and was converted to
the NASA Directory Interchange Format.