Vegetation Classification and Mapping Project Report - USGS

USGS-NPS Vegetation Mapping Program
Colonial National Historical Park
The five remaining upland associations occur as small patches in specialized habitats. Two
associations, Coastal Plain Mesic Calcareous Ravine Forest (20.4 ha [50.3 ac]) and Coastal Plain
Dry Calcareous Forest (5.8 ha [14.3 ac]), are found on slopes of ravines that cut into Tertiary
shell deposits or limesands, including the Pliocene marine shell deposits of the calcium-rich
Yorktown Formation. Coastal Plain Mesic Calcareous Ravine Forest is on more mesic, north- to
northwest-facing slopes and was mapped at College Creek / Kingsmill, as small patches on the
ravine slopes of Yorktown Creek and its tributary, and on the slopes over Wormley Pond.
Coastal Plain Dry Calcareous Forest is on dry, convex, southeast- to southwest-facing slopes and
is mapped in the vicinity of Yorktown Battlefield on the ravine slopes of Ballard Creek, around
Wormley Pond, and at King Creek / Ringfield. Coastal Plain Dry Calcareous Forest is
distinguished from Coastal Plain Mesic Calcareous Ravine Forest by its more open canopy
structure, more graminoid species cover, the occurrence of eastern redcedar (Juniperus
virginiana var. virginiana), and the general absence of mesophytic species that characterize
Coastal Plain Mesic Calcareous Ravine Forest such as pawpaw (Asimina triloba), northern
spicebush (Lindera benzoin), bloodroot (Sanguinaria canadensis), northern maidenhair
(Adiantum pedatum), and black bugbane (Cimicifuga racemosa). Also, Coastal Plain Mesic
Calcareous Ravine Forest tends to have a better developed herbaceous strata with upwards of 50­
75% coverage. Both communities have very restricted ranges, and high quality examples are
uncommon. Coastal Plain Mesic Calcareous Ravine Forest is endemic to the southeastern
Virginia Coastal Plain, and Coastal Plain Dry Calcareous Forest is only known from fewer than
30 scattered locations in the Coastal Plain of Virginia and Maryland. Timber harvest or other
canopy disturbances degrade this community by allowing additional light and aggressive growth
of invasive, nonnative plants which thrive in well-lit, calcareous situations and compete with the
native flora. The examples of these communities in Colonial National Historical Park represent
some of the few protected examples in the world. Areas mapped as the transitional vegetation
class Disturbed Calcareous Forest (see above) may have formerly been either Coastal Plain
Mesic Calcareous Ravine Forest or Coastal Plain Dry Calcareous Forest, but now have a species
composition too altered to assign them a natural community classification.
Acidic Oak - Hickory Forest, Piedmont / Coastal Plain Oak - Beech / Heath Forest, and
Piedmont / Low Elevation Mixed Oak / Heath Forest are three upland forest classes that occur
over acidic, nutrient-poor soils. Acidic Oak - Hickory Forest is mapped on short, steep slopes
and associated flat areas above tidal marshes at Ringfield / King Creek and at College Creek /
Kingsmill, covering a total area of 18.9 ha (46.8 ac) in 12 patches. Acidic Oak - Hickory Forest
ranges through the Piedmont of the Carolinas and Virginia, north into south-central Maryland,
extending into the inner Coastal Plain in parts of Virginia. Throughout most of its range, it is a
matrix or large-patch forest. However, on inner Coastal Plain landscapes, such as Colonial
National Historical Park, Acidic Oak-Hickory Forest is often found as a small patch forest. It is
not a rare community type (G4G5), but extensive stands and stands older than about 80 years old
are uncommon, since most of the rolling upland landscapes of the Piedmont have been logged
repeatedly since European settlement or converted to pine plantations. Acidic Oak – Hickory
Forest was mapped in six of the seven parks included in this study. Piedmont / Coastal Plain
Oak - Beech / Heath Forest is mapped on a total of 7.6 ha (18.7 ac) at College Creek / Kingsmill,
Papermill Creek, and on the ravine slopes of Ballard Creek and Yorktown Creek in the vicinity
of Yorktown Battlefield. It is distinguished from other forests by its occurrence on steep slopes
and the presence of a dense shrub layer of mountain laurel (Kalmia latifolia). Some polygons
mapped as this type may be similar to Mesic Mixed Hardwood Forest, but usually occupy drier,
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