Vegetation Classification and Mapping Project Report - USGS

USGS-NPS Vegetation Mapping Program
Colonial National Historical Park
GLOBAL INFORMATION
USNVC CLASSIFICATION
Physiognomic Class Shrubland (III)
Physiognomic Subclass Deciduous shrubland (III.B.)
Physiognomic Group Cold-deciduous shrubland (III.B.2.)
Physiognomic Subgroup Natural/Semi-natural cold-deciduous shrubland (III.B.2.N.)
Formation Tidal cold-deciduous shrubland (III.B.2.N.h.)
Alliance Baccharis halimifolia - Iva frutescens Tidal Shrubland Alliance (A.1023)
Alliance (English name) Groundsel-tree - Maritime Marsh-elder Tidal Shrubland Alliance
Association Baccharis halimifolia - Iva frutescens / Panicum virgatum Shrubland
Association (English name) Groundsel-tree - Maritime Marsh-elder / Switchgrass Shrubland
Ecological System(s): Atlantic Coastal Plain Embayed Region Tidal Salt and Brackish Marsh
(CES203.260).
Atlantic Coastal Plain Northern Salt Pond Marsh (CES203.892).
Northern Atlantic Coastal Plain Tidal Salt Marsh (CES203.519).
Central Atlantic Coastal Plain Salt and Brackish Tidal Marsh (CES203.270).
GLOBAL DESCRIPTION
Concept Summary: This maritime shrubland of the eastern states occurs in association with
salt marshes. Iva frutescens (Jesuit's bark) is the most characteristic and dominant shrub species,
and Baccharis halimifolia (eastern baccharis) is a common associate. Other associated shrubs
include Morella pensylvanica (northern bayberry) in the northern portion of the range, while
Borrichia frutescens (bushy seaside tansy), Morella cerifera (wax myrtle), and Juniperus
virginiana var. silicicola (southern redcedar) are frequent associates in the southern part of the
range. Spartina patens (saltmeadow cordgrass) is a characteristic and usually abundant grass;
other common herbaceous associates include Panicum virgatum (switchgrass), Distichlis spicata
(inland saltgrass), Hibiscus moscheutos ssp. moscheutos (crimsoneyed rosemallow),
Toxicodendron radicans (eastern poison ivy), Teucrium canadense (Canada germander), Festuca
rubra (red fescue), Limonium carolinianum (Carolina sealavender), Atriplex prostrata (triangle
orache), Sabatia stellaris (rose of Plymouth), Sabatia dodecandra (marsh rose gentian), and in
the north Hierochloe odorata (vanilla grass) and Juncus gerardii (saltmeadow rush), and in the
south Setaria parviflora (marsh bristlegrass). This community often forms an abrupt transition
from salt marsh to upland reflecting the relatively higher elevation and less frequent tidal
flooding. Shrub cover in this situation tends to be fairly dense, and herbs are sparsely distributed.
Storm-induced disturbance causes periodic die-back of the shrubs restricting the extent of their
spread.
Environmental Description: This maritime and estuarine shrubland of the northeastern
seaboard states occurs in association with salt marshes. It forms an ecotone between high salt
marsh and adjacent upland vegetation. This shrubland occurs above mean high tide but can be
flooded by storm tides. Substrate is organic peat over glacial till, sand, or sandy loam.
Vegetation Description: This tidal shrubland is dominated by Iva frutescens (Jesuit's bark) and
Baccharis halimifolia (eastern baccharis). Other associated shrubs include Morella pensylvanica
(northern bayberry) in the northern portion of the range, while Borrichia frutescens (bushy
seaside tansy), Morella cerifera (wax myrtle), and Juniperus virginiana var. silicicola (southern
redcedar) are frequent associates in the southern part of the range. Panicum virgatum
(switchgrass) is a characteristic and usually abundant grass; other common herbaceous associates
include Distichlis spicata (inland saltgrass), Hibiscus moscheutos ssp. moscheutos (crimsoneyed
rosemallow), Toxicodendron radicans (eastern poison ivy), Teucrium canadense (Canada
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