Print Report

CEGL004192 Spartina alterniflora North Atlantic Salt Marsh

Type Concept Sentence: No Data Available

Common (Translated Scientific) Name: Smooth Cordgrass North Atlantic Salt Marsh

Colloquial Name: North Atlantic Low Salt Marsh

Hierarchy Level:  Association

Type Concept: This tall grassland dominated by Spartina alterniflora forms the low salt marsh of the north and mid-Atlantic Coast. It is diurnally flooded by tides, occurring in the intertidal zone between mean high tide and mean sea level in protected inlets behind barrier beaches or in the seaward reaches of drowned river valleys. It forms a coarse peat over sandy substrate. The low salt marsh occurs elevationally between high marsh that occurs landward and subtidal communities that occur seaward. Spartina alterniflora is limited to the low marsh zone by interspecific competition and by moderate salinity; it can withstand longer submergence than other salt marsh grasses but still requires periodic exposure of the substrate. Spartina alterniflora forms nearly monotypic stands with little variation across the geographic range of the community. Tall form Spartina alterniflora occurs adjacent to salt water and colonizes unvegetated flats. Associated species occur in low abundance and commonly include Limonium carolinianum, Salicornia depressa, Salicornia bigelovii, Spergularia maritima, Spergularia canadensis, and Suaeda maritima. Brown algae can form extensive mats at the bases of the grass culms, especially Ascophyllum nodosum, Fucus vesiculosus, Enteromorpha spp., and Ulva spp. Macroalgae associates may be sparse or absent at the southern edge of the range. This community occurs from Labrador to Virginia. Low marshes at the northern edge of the geographic range are far less extensive in size than those farther south due to differences in geomorphology and time since last glaciation.

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: This association can be differentiated from its mid-Atlantic counterpart ~Spartina alterniflora - Distichlis spicata Tidal Salt Marsh (CEGL006586)$$ by its near absence of other vascular plants. In general, this association is characterized by tall (>1 m) Spartina alterniflora, although the short form of this species is not unusual. In the mid-Atlantic, the low salt marshes are usually codominated by a short form of Spartina alterniflora and Distichlis spicata. The floristic difference between the two associations may be explained by the lesser tidal amplitude in the mid-Atlantic (Flick and Ewing 1999), but further study is needed to confirm. Distribution southward is debatable, but currently extends to North Carolina.

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: No Data Available

Floristics: This community is a tall grassland dominated by Spartina alterniflora occurring in regularly flooded intertidal zones. Spartina alterniflora dominates this physically stressful zone due to limited competition and its ability to tolerate salinity and flooding. It also requires moderately high levels of iron (7-15 ppm) (Adams 1963). Spartina alterniflora is strongly dominant, forming a nearly monotypic tallgrass layer. There is little variation in vascular plant composition across the range. Tall-form Spartina alterniflora occurs adjacent to saltwater and colonizes unvegetated flats. This association also grades into short-form Spartina alterniflora landward where tidal range is more restricted. Common associates, occurring in low abundance, include Limonium carolinianum, Salicornia depressa (= Salicornia virginica), Salicornia bigelovii, Spergularia maritima, Spergularia canadensis, and Suaeda maritima. Distichlis spicata, Agalinis maritima, Symphyotrichum tenuifolium (= Aster tenuifolius), and Spartina patens can also sporadically occur, but are more common in the high salt marsh. Brown algae can form extensive mats at the bases of the grass culms, especially Ascophyllum nodosum, Fucus vesiculosus, and Ulva spp. Enteromorpha spp. can occur early in the growing season. Macroalgae associates may be sparse or absent at the southern edge of the range. Microscopic algae, especially diatoms, can be abundant on the marsh surface (Teal 1986).

Dynamics:  Salt marshes are dynamic habitats. Spartina alterniflora readily colonizes soft sediments off the seaward edge of the salt marsh (Bertness 1988). Grass culms and algal mats trap sediments brought in by the tides and begin the process of marsh peat accumulation. As peat development raises marsh elevation, low marsh succeeds to high marsh communities; Spartina alterniflora performance declines as peat accumulates and becomes more dense. Flotsam and jetsam brought in by tides can smother local patches of vegetation and form unvegetated to sparsely vegetated pannes, a phenomenon that occurs regularly on high marshes. Tidal creeks form sinuous patterns throughout the low marsh draining the diurnal tides.
Environmental Description:  This low salt marsh community occurs in the regularly flooded intertidal zone, approximately from mean high tide to mean sea level; it is diurnally flooded by tides and classified as polyhaline (18-30 ppt). This low marsh occurs in areas sheltered from direct wave action, such as behind barrier beaches, as pocket marshes at the heads of bays, or in the outer reaches of estuaries. Low salt marshes occur landward of intertidal flats and subtidal communities and seaward of high salt marsh communities. Low salt marshes dominated by Spartina alterniflora generally occur on mucky silt to silty coarse fibrous peat, often with high organic matter content. However, peat in the low marsh is generally less dense than farther landward (Bertness 1988). Peat depth ranges from a few feet, if the community formed over a mudflat, to 24 m (80 feet) in drowned river valleys at the mouths of estuaries.
Geographic Range: This association occurs along the Atlantic coastline from Labrador and New Brunswick south to North Carolina.

Nations: CA,US

States/Provinces:  CT, DE, MA, MD, ME, NB, NC, NH, NJ, NS, NY, QC?, RI, VA


Confidence Level: Moderate

Confidence Level Comments: No Data Available
Grank: G5

Greasons: No Data Available
Type Name Database Code Classification Code
Class 2 Shrub & Herb Vegetation Class C02 2
Subclass 2.C Shrub & Herb Wetland Subclass S44 2.C
Formation 2.C.5 Salt Marsh Formation F035 2.C.5
Division 2.C.5.Nb North American Atlantic & Gulf Coastal Salt Marsh Division D034 2.C.5.Nb
Macrogroup 2.C.5.Nb.1 North American Atlantic & Gulf Coastal Salt Marsh Macrogroup M079 2.C.5.Nb.1
Group 2.C.5.Nb.1.a Smooth Cordgrass Low Salt Marsh Group G122 2.C.5.Nb.1.a
Alliance A4498 Smooth Cordgrass North Atlantic Low Salt Marsh Alliance A4498 2.C.5.Nb.1.a
Association CEGL004192 Smooth Cordgrass North Atlantic Salt Marsh CEGL004192 2.C.5.Nb.1.a
Concept Lineage: No Data Available

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: = Spartina alterniflora / (Ascophyllum nodosum) Acadian/Virginian Zone Herbaceous Vegetation (Fleming et al. 2007b)
= Spartina alterniflora Herbaceous Vegetation (Clancy 1996)
= Spartina alterniflora Tidal Herbaceous Vegetation (Harrison 2001)
= Spartina alterniflora community (Metzler and Barrett 2006)
? Salt Marsh (Rawinski 1984a) [formerly Southern New England and Gulf of Maine Salt Marshes.]
Concept Author(s): Eastern Ecology Group

Author of Description: S.L. Neid

Acknowledgements: No Data Available

Version Date: 11-29-16
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