Vegetation Classification and Mapping Project Report - USGS

USGS-NPS Vegetation Mapping Program
Colonial National Historical Park
steeper sites that support fewer mesophytic plants and a greater abundance of heath shrubs.
Colonial National Historical Park was the only park in this study where this community was
documented. In Virginia, Piedmont / Coastal Plain Oak - Beech Heath Forest is common in the
fall-line zone of the Piedmont and adjacent inner Coastal Plain, but is also found on dissected
landscapes in the outer Piedmont and the northern Coastal Plain north of James River and
occasionally on short, steep bluffs bordering outer Coastal Plain estuaries. It ranges north to
New Jersey. Piedmont / Low Elevation Mixed Oak / Heath Forest is found on xeric sites over
well-drained, sandy soils derived from fluvial terrace gravels. It is mapped as a single polygon
in the College Creek / Kingsmill area of Colonial National Historical Park, where it covers 0.9 ha
(2.2 ac). The vegetation in Colonial National Historical Park was classified as this association
because of the dominance of black huckleberry (Gaylussacia baccata) and presence of chestnut
oak (Quercus prinus), two species more typical of oak / heath forests in the Piedmont and low
elevations of the Central Appalachians. Piedmont / Low Elevation Mixed Oak / Heath Forest is
found in three of the seven national parks included in this study. It is a widespread, matrixforming
forest community known from nutrient-poor uplands of Virginia’s Piedmont and inner
Coastal Plain, and at low elevations in the northern Blue Ridge and Ridge and Valley. It also
extends north into Maryland and south to low elevations of Tennessee’s Cumberland Plateau.
Of the 40 map classes used to map the vegetation at Colonial National Historical Park, eighteen
are equal to natural communities as defined in the Natural Communities of Virginia
(http://www.dcr.virginia.gov/natural_heritage/nctoc.shtml). Exemplary occurrences of these
communities are tracked by Virginia’s Department of Conservation and Recreation, Division of
Natural Heritage. In order to be considered an exemplary occurrence, stands have to meet strict
type-specific criteria of size, condition, and landscape context. Examples of seven natural
communities mapped at Colonial National Historical Park met the criteria to be considered
Natural Heritage exemplary natural community occurrences. A portion of the area mapped as
Non-Riverine Saturated Forest at Green Spring met the criteria to be considered a Natural
Heritage exemplary natural community occurrence. Examples of Coastal Plain Calcareous
Seepage Swamp mapped at Swanns Point, in a ravine system in the northern portion of
Yorktown Battlefield, and in a ravine south of Wormley pond, met the criteria to be considered
Natural Heritage exemplary natural community occurrences. The other areas mapped as Coastal
Plain Calcareous Seepage Swamp were too disturbed to be considered viable exemplary
occurrences. The globally rare community Coastal Plain Depression Wetland (Swamp Tupelo
Type), mapped in the southern portion of Yorktown Battlefield, met the criteria to be considered
a Natural Heritage exemplary natural community occurrence, and is part of the larger Grafton
Pond depression pond complex that extends onto property adjacent to Colonial National
Historical Park. The example of Tidal Bald Cypress Forest / Woodland mapped at Swanns Point
is a Natural Heritage exemplary natural community occurrence. Small areas of Tidal Bald
Cypress Forest / Woodland mapped at Jamestown Island are disturbed and have been cut off
from natural tidal flooding regimes and do not meet the criteria to be considered exemplary
occurrences. The Coastal Plain Mesic Calcareous Ravine Forests mapped at Wormley Pond, in
the ravine system north of Hickory Hill, and at Kingsmill are considered Natural Heritage
exemplary natural community occurrences. The other areas mapped as this association were
either not confirmed in the field or are too disturbed to be considered viable exemplary
occurrences. All areas mapped as the globally rare community Coastal Plain Dry Calcareous
Forest met the criteria to be considered Natural Heritage exemplary natural community
occurrences. The Tidal Oligohaline Marsh around Jamestown Island is documented as a Natural
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