Vegetation Classification and Mapping Project Report - USGS

Introduction
● Metadata for each spatial dataset follows
the FGDC metadata standard.
● Spatial data is provided with a horizontal
positional accuracy that meets
National Map Accuracy Standards at
the 1:24,000 scale; each well-defined
object within the spatial database is
within 1/50 of an inch display scale or
12.2 meters (40 ft) of its actual location.
● All plant names used in the classification
are consistent with the Integrated
Taxonomic Information System (ITIS).
● Each vegetated map class will meet or
exceed 80% accuracy at the 90% confidence
level.
● The minimum mapping unit (MMU) is
0.5 ha (1.24 ac).
1.4 The National Vegetation
Classification Standard
Patterns of vegetation vary continuously
over landscapes. Classification systems
attempt to categorize those patterns by
identifying and describing assemblages of
plants that repeat in similar habitats. The
NVCS provides a classification framework
that is the standard for all NPS vegetation
mapping projects (Comer et al. 2003, The
Nature Conservancy, and Environmental
Systems Research Institute 1994a). In
1997, the FGDC formally adopted the
NVCS Version 1 (Federal Geographic Data
Committee 1997). During the course of the
project, Version 2 of the NVCS (Federal
Geographic Data Committee 2008) was
approved, but it was not used in this
project as the vegetation classification
units were still under development.
Not to be confused with the National
Vegetation Classification (NVC) described
below, the NVCS refers to the framework
and rules of classification and evolved
from vegetation classification work
conducted over more than two decades
by The Nature Conservancy (TNC),
NatureServe, and the Natural Heritage
Program network (Grossman et al. 1998).
It derives in part from earlier vegetation
classification schemes produced by the
United Nations Educational, Cultural,
and Scientific Organization (UNESCO)
(UNESCO 1973, Driscoll et al. 1984).
Use of this standardized classification
system helps ensure data compatibility
throughout the National Park Service and
other agencies.
The NVCS is a hierarchical system that
allows vegetation classification to occur
at multiple scales. In Version 1, there
are seven levels: the upper five are based
on the physiognomic characteristics of
vegetation, and the lower two are based
on the floristic characteristics of the plant
community. Version 2 (Federal Geographic
Data Committee 2008) has eight levels
(table 2). The upper three levels (which
are a reorganization of the five upper
physiognomic levels from Version 1)
indicate physiognomic characteristics
that reflect geographically widespread
(global) topographic and edaphic factors.
The middle three levels, which are new
to the NVCS hierarchy, focus on largely
biogeographic and habitat factors along
very broad regional-to-continental
topographic, edaphic, and disturbance
gradients. The lower two levels—alliance
and association—are used in the park
mapping project and are the same in
both Version 1 and Version 2, with some
changes to Version 2 alliances expected.
Because the Group level in NVCS,
Version 2 was still under development,
NatureServe Ecological Systems were
used to approximate the group level for
the PEFO group map classes.
The NVCS provides a framework for levels
of classification, but it does not provide
descriptions of the vegetation types at all
levels. The classification maintained by
NatureServe and used by many federal
agencies (including the NPS) is the NVC.
The NVC includes the plant communities
(associations and alliances) identified
and described in the United States. Work
conducted primarily by TNC through
1999 provided initial definitions of plant
communities at each level. NatureServe
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