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G122 Spartina alterniflora Low Salt Marsh Group

Type Concept Sentence: These are salt marshes found along the North American Atlantic and Gulf of Mexico coasts from the Bay of Fundy to Texas and possibly Mexico, typically dominated by Spartina alterniflora.

Common (Translated Scientific) Name: Smooth Cordgrass Low Salt Marsh Group

Colloquial Name: Atlantic & Gulf Coastal Low Salt Marsh

Hierarchy Level:  Group

Type Concept: This group encompasses salt marsh vegetation that is flooded twice daily by polyhaline waters and dominated by Spartina alterniflora. Spartina alterniflora is constant, dominant, and sometimes monospecific. Halophytic forbs (or forblike woody plants in the case of Sarcocornia) such as Sarcocornia perennis may be present though not abundant, and individuals of species more common in the high marsh, such as Limonium carolinianum, Juncus roemerianus, and Distichlis spicata, may also occur. Other species include Limonium carolinianum, Plantago maritima, Salicornia spp., Spartina patens, and Spergularia canadensis. Macroalgae such as Ascophyllum nodosum may be present (though sparse) particularly in the northern part of the group''s range. It is often found fringing tidal creeks, and in places forms extensive flats of low marsh vegetation.

Diagnostic Characteristics: Graminoid coastal marsh vegetation in which Spartina alterniflora is strongly dominant and often monospecific. Brackish water associates such as Schoenoplectus spp., Spartina cynosuroides, or Spartina pectinata are absent.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: Salt marsh zonation has long been recognized and well-studied. The four groups in ~North American Atlantic & Gulf Coastal Salt Marsh Macrogroup (M079)$$ reflect these common salt marsh zones (low marsh, high marsh, brackish marsh, panne); see, for example, Adam (1990) and Mendelssohn and McKee (2000).

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: Spartina alterniflora dominates the dense graminoid flats of this vegetation. This species grows in both a tall form and a short form (Valiela et al. 1978). The tall form (generally over 1 m in height) is common along tidal creeks and at marsh edges; the short form (10-40 cm tall) is typically found in more extensive flats landward of the tall form.

Floristics: Spartina alterniflora is constant, dominant, and sometimes monospecific. Halophytic forbs (or forblike woody plants in the case of Sarcocornia) such as Sarcocornia perennis may be present though not abundant, and individuals of species more common in the high marsh, such as Limonium carolinianum, Juncus roemerianus, and Distichlis spicata, may also occur. Other species include Limonium carolinianum, Plantago maritima, Salicornia spp., Spartina patens, and Spergularia canadensis. Macroalgae such as Ascophyllum nodosum may be present (though sparse) particularly in the northern part of the group''s range.

Dynamics:  Storm tides often deposit sand on salt marsh surfaces where overwash breaches the barrier dune. Flood-deposited wrack can smother the underlying marsh, converting it to an unvegetated flat. Decline of low salt marsh has been documented on the Atlantic and Gulf coasts in recent decades; loss is attributed to intense grazing by a nocturnal crab, which is most pronounced at tidal creek edges (Smith 2009).
Environmental Description:  Climate: Cool-temperate to warm-temperate maritime climate. Soil/substrate/hydrology: Tides bring nutrients, making the regularly flooded marshes fertile. Salt marshes generally develop on fine-grained sediments, but can develop over sands as well. Production exceeds decomposition, leading to the buildup of marsh peat. Low marsh is flooded twice daily by polyhaline waters as a result of lunar, wind and storm tides.
Geographic Range: This vegetation is found along the North American Atlantic and Gulf of Mexico coasts from the Bay of Fundy south to Texas and possibly Mexico.

Nations: CA,MX?,US

States/Provinces:  AL, CT, DE, FL, GA, LA, MA, MD, ME, MS, MXTAM?, NB, NC, NH, NJ, NS, NY, QC, RI, SC, TX, VA


Confidence Level: Low

Confidence Level Comments: No Data Available
Grank: GNR

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 A4497 Smooth Cordgrass South Atlantic-Gulf Low Salt Marsh Alliance A4497 2.C.5.Nb.1.a
Alliance A4498 Smooth Cordgrass North Atlantic Low Salt Marsh Alliance A4498 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: < Estuarine Persistent Emergent Wetland (Cowardin et al. 1979)
= Low Marsh (Mendelssohn and McKee 2000)
= Low Marsh (Adams 1963)
> Salt marsh ecosystem (Odum and Copeland 1974)
Concept Author(s): D. Faber-Langendoen, L. Sneddon, and C. Nordman, in Faber-Langendoen et al. (2011)

Author of Description: S.C. Gawler, L. Sneddon, M. Pyne and D. Faber-Langendoen

Acknowledgements: Sean Basquill

Version Date: 06-05-15
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  • Adams, D. A. 1963. Factors influencing vascular plant zonation in North Carolina salt marshes. Ecology 44:445-456.
  • Cowardin, L. M., V. Carter, F. C. Golet, and E. T. LaRoe. 1979. Classification of wetlands and deepwater habitats of the United States. FWS/OBS-79/31. USDI Fish & Wildlife Service, Office of Biological Services, Washington, DC. 103 pp.
  • Diamond, D. D. 1993. Classification of the plant communities of Texas (series level). Unpublished document. Texas Natural Heritage Program, Austin. 25 pp.
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  • Mendelssohn, I. A., and K. L. McKee. 2000. Saltmarshes and mangroves. Pages 501-536 in: M. G. Barbour and W. D. Billings, editors. North American terrestrial vegetation. Second edition. Cambridge University Press, New York. 434 pp.
  • Nelson, J. B. 1986. The natural communities of South Carolina: Initial classification and description. South Carolina Wildlife and Marine Resources Department, Division of Wildlife and Freshwater Fisheries, Columbia, SC. 55 pp.
  • Odum, H. T., and B. J. Copeland. 1974. A functional classification of the coastal systems of the United States. H. T. Odum, B. J. Copeland, and E. A. McMahan, editors. Coastal Ecological Ecosystems of the United States. Volume I. The Conservation Foundation. Washington, DC.
  • Odum, W. E. 1988. Comparative ecology of tidal freshwater and salt marshes. Annual Review of Ecological Systems 19:147-176.
  • Smith, S. M. 2009. Multi-decadal changes in salt marshes of Cape Cod, MA: Photographic analyses of vegetation loss, species shifts, and geomorphic change. Northeast Naturalist 16:183-208.
  • Tiner, R. W., Jr. 1977. An inventory of South Carolina''s coastal marshes. South Carolina Marine Resources Center. Technical Report 23. Columbia, SC. 33 pp.
  • Valiela, I., J. M. Teal, and W. G. Deuser. 1978. The nature of growth forms in the salt marsh grass Spartina alterniflora. The American Naturalist 112:461-470.