Vegetation Classification and Mapping Project Report - USGS

USGS-NPS Vegetation Mapping Program
Colonial National Historical Park
For non-natural types, a Global Rank of GNA = Rank not applicable is assigned. They are
further identified as one from the following:
Cultural - indicates that the Association is cultivated. Planted/cultivated areas are defined
as being dominated by vegetation that has been planted in its current location by
humans and/or is treated with annual tillage, a modified conservation tillage, or other
intensive management or manipulation. The majority of these areas are planted
and/or maintained for the production of food, feed, fiber, or seed.
Ruderal - indicates that the Association is considered ruderal. Ruderal communities are
vegetation resulting from succession following anthropogenic disturbance of an area.
They are generally characterized by unnatural combinations of species (primarily
native species, though they often contain slight to substantial numbers and amounts of
species alien to the region as well). In many landscapes, ruderal communities occupy
large areas - sometimes more than any other category of communities - and can
provide important biodiversity functions.
Modified/Managed - indicates that the Association is modified or managed.
Modified/managed communities are vegetation resulting from the management or
modification of natural/near-natural vegetation, but producing a structural and
floristic combination not clearly known to have a natural analogue. Modified
vegetation may be easily restorable by either management, time, or restoration of
ecological processes. It is not yet clear how to deal with these communities in the
USNVC.
Invasive - indicates that the Association is weedy and invasive. Invasive communities
are dominated by invasive alien species. Although these communities are often
casually considered as “planted/cultivated,” they are spontaneous, self-perpetuating,
and not the (immediate) result of planting, cultivation, or human maintenance. Land
occupied by invasive communities is generally permanently altered (converted)
unless restoration efforts are undertaken. It is also important to recognize that these
communities are novel; they are not merely a community “transplanted” from the
native range of the dominant species. Melaleuca in south Florida, kudzu in the
southeastern United States, tamarisk in the western United States, and red mangrove
in Hawaii all form communities which have no equivalent in the native range of the
dominant species (associated species, processes, landscape context, fauna, etc., are all
significantly different).
Reasons: Reasons that the Heritage Conservation Status Global Rank for the Association was
assigned, including key ranking variables and other considerations used.
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