The Natural Communities of Virginia
Classification of Ecological Community Groups
SECOND APPROXIMATION (Version 2.2)
Upper Beaches and Overwash Flats
The Marine System is represented by a single group containing vascular plants, which are associated with sparsely vegetated ocean shores and
flats behind breached foredunes. Similar vegetation occurs from Maine south to South Carolina. Upper-beach habitats are situated just above the
mean high tide limit, but are flooded by high spring tides and storm surges. Constant salt spray maintains generally moist conditions.
Substrates consist of unconsolidated sand and shell sediments that are constantly shifted by winds and floods. Dynamic disturbance regimes
largely limit vegetation to pioneering, salt-tolerant, succulent annuals. American searocket (
Cakile edentula) and/or Carolina saltwort
(
Salsola caroliniana) are usually most
numerous and characteristic. Other scattered associates include sea-purslane (
Sesuvium maritimum), sea-beach knotweed
(
Polygonum glaucum), bushy knotweed (
Polygonum ramosissimum var. prolificum), sea-blites (
Suaeda linearis and
(
Suaeda maritima ssp. maritima),
and sea-beach orach (
Atriplex arenaria). In Virginia, these communities are distributed along the ocean side of the Eastern Shore
(Accomack and Northampton Counties) and on Cape Henry and False Cape (City of Virginia Beach).
Upper beach / overwash flat habitats are critical to several globally rare, federally listed species, including the northeastern beach
tiger beetle (Cicindela dorsalis
dorsalis). The threatened plant seabeach amaranth (Amaranthus pumilus) occurred historically on overwash flats in both Eastern Shore counties. The loggerhead sea turtle (Caretta caretta) and the piping plover (Charadrius melodus melodus) utilize beaches and overwash flats for nesting. Extensive construction of high, artificial dunes along the Atlantic coast has reduced the extent of these habitats by increasing oceanside beach erosion
and eliminating the disturbance regime that creates and maintains overwash flats.
References: Clampitt (1991), The Nature Conservancy (1997).
Click on the images below to open a larger image in a separate window.
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Succulent, annual, upper-beach vegetation on Parramore Island, a maritime barrier island in
Accomack County. Carolina saltwort (Salsola caroliniana) is the dominant species in this stand.
Photo: Tom Rawinski / © DCR Natural Heritage.
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Clumps of Carolina saltwort (Salsola caroliniana) on an extensive
overwash flat at the southern tip of the Eastern Shore in Northampton County (Fisherman's Island National Wildlife
Refuge).
Photo: Irvine Wilson / © DCR Natural Heritage. |
REPRESENTATIVE COMMUNITY TYPES:
Quantitative data have been collected from just two plots of Upper Beach / Overwash Flat vegetation in Virginia.
While sampled and observed Virginia stands unquestionably match the USNVC association listed below in general concept, they exhibit
apparently significant compositional variation from one locality to another. More data collection and analysis are therefore needed to
capture the range of this variation over the state's coastline, firm up classification at the community-type level, and assess the
conservation status of this group.
Click on any highlighted CEGL code below to view the global USNVC description provided by
NatureServe Explorer.
- Cakile edentula ssp. edentula - Chamaesyce polygonifolia Sparse Vegetation
North Atlantic Upper Beach / Overwash Flat
USNVC:
CEGL004400
Global/State Ranks:
G4G5/S?
