Vegetation Classification and Mapping Project Report - USGS

USGS-NPS Vegetation Mapping Program
Colonial National Historical Park
Location and Regional Setting
Project Area
Colonial National Historical Park is located in the middle of Virginia’s Coastal Plain (Figure 2).
This region is also known as the “The Peninsula” or the “Lower Peninsula”, one of three
prominent peninsulas formed as four large tidal rivers dissect the Coastal Plain, draining into the
Chesapeake Bay. The Lower Peninsula is bounded by the York River to the north, the
Chesapeake Bay to the east, and the James River to the south. The park boundaries fall within
seven USGS quadrangle maps: Clay Bank, Hog Island, Norge, Poquoson West, Surry,
Williamsburg, and Yorktown (Figure 3). The majority of the park is in a portion of the Coastal
Plain known as the Atlantic Southern Loam Hills subsection that is characterized by smooth
plains ranging from 30 to 91 m (100 to 300 ft) (Keys et al. 1995). Jamestown Island is in the
Chesapeake Bay subsection of the Atlantic Coastal Flatwoods section, and the eastern portion of
Yorktown is in the Tidal Area subsection of the Atlantic Coastal Flatwoods section, an area of
flat plains with elevations ranging from 0–30 m (0–100 ft) (Keys et al. 1995.) Historical climate
data from Williamsburg, Virginia (37°18'N / 76°42'W) from the years 1948 through 2007 report
the mean monthly minimum temperature as 8.6º C (47.5º F), and the mean monthly maximum
temperature is 21.0º C (69.9º F). The mean January minimum temperature is –2.0º C (28.3º F),
and the mean July maximum temperature is 31.4º C (88.5º F). Annual precipitation averages
102.9 cm (47.63 in), with snowfall of 18.3 cm (7.2 in) (Southeast Regional Climate Center
2008).
The upland forests that originally covered much of Virginia’s Coastal Plain have been
extensively cleared or altered, so that it is now difficult to determine which species and natural
communities were historically prevalent. Much of the contemporary forest consists of
successional or silvicultural stands of loblolly pine (Pinus taeda) and secondary pine-hardwood
forests that have developed after repeated cutting or agricultural abandonment. The most mature
remnant stands on mesic uplands are characterized by associations of American beech (Fagus
grandifolia), several oaks (Quercus spp.), and American holly (Ilex opaca var. opaca),
representing what once was the common, matrix-forming forest type in region. Patches of drier
oak-dominated forest and steep bluffs with forests of chestnut oak (Quercus prinus), American
beech, and dense mountain laurel (Kalmia latifolia) are fairly common in the dissected inner
Coastal Plain, especially north of the James River. South of the James River, fire-maintained
forests and woodlands dominated by longleaf pine (Pinus palustris) may have been prevalent
prior to European settlement (Frost 1995), but little trace of these now remain. The Coastal Plain
also supports terrestrial communities that are restricted to special habitats on ravine slopes and
estuarine-fronting bluffs that have down-cut into Tertiary shell deposits or limesands. Soils of
these forests and woodlands have extraordinarily high levels of calcium and support a number of
inland, calciphilic species that are disjunct from the mountains. Wetlands of the Coastal Plain
are extensive and have fared somewhat better than the province’s upland forests, supporting a
great variety of natural communities. The diversity of wetlands in this region spans a range of
freshwater to saline, lunar-tidal estuaries; tidal and palustrine swamps; nonriverine, groundwatersaturated
flats; seasonally flooded ponds and depressions; seepage slope wetlands; and various
tidal and non-tidal aquatic habitats.
21