Natural Communities of NH -- Photo Guide

High salt marsh  (S3)



High salt marsh
is the most common salt marsh community, accounting for more than 90% of the total salt marsh habitat in New Hampshire. It is strongly dominated by salt-meadow cordgrass (Spartina patens), and occurs within the reach of higher than average high tides (including spring tides and storm surges). The upper edge of this community is only flooded during spring tides and storm surges and supports a broad diversity of plant species. 

Both high and low salt marshes occur along the coast behind rocky spits, barrier beaches, and sand bars and along bays and rivers where they are protected from high-energy wave action. The transition between this community and low salt marsh occurs approximately at the mean high water mark; from here this community stretches landward to the upper reaches of spring tides. This community grades into low salt marsh, intertidal flats, and subtidal communities seaward and, depending on local conditions, brackish marsh, fresh water wetlands, or upland communities landward. Salt pannes and pools can frequently be found within the high salt marsh.

Soils are generally organic materials thicker than 50" over sand, silt, or bedrock. Lesser amounts of organic material (<16") over sand underlie this community at the extreme seaward edge of coastal margins, small areas on the Great Bay’s western side, and along some streams flowing into the bay. Salt marsh soil water salinity roughly corresponds to polyhaline levels (18–30 ppt).

Characteristic vegetation:
Salt-meadow cordgrass (Spartina patens) is strongly dominant. Other common, occasional, or locally abundant plants include the short form of smooth cordgrass (Spartina alterniflora), spike grass (Distichlis spicata), salt marsh rush (Juncus gerardii), red fescue (Festuca rubra), New York aster (Symphyotrichum novi-belgii), seaside goldenrod (Solidago sempervirens), switch grass (Panicum virgatum), vanilla grass (Hierochloe odorata), fresh-water cordgrass (Spartina pectinata), small salt marsh aster (Symphyotrichum subulatum), salt marsh plantain (Plantago maritima), salt marsh gerardia (Agalinis maritima), and sea milkwort (Glaux maritima).

Spike-grass often forms pure stands in wetter, more poorly drained areas, or mixes with salt-meadow cord-grass, growing at similar elevations on the high marsh. Salt marsh rush often dominates landward of salt-meadow cord-grass in narrow vegetative zones with decreased tidal flooding and soil water salinity, beginning at about mean spring high water. Only spring tides and storm surges reach this area along the upper edge of the community. This zone has the highest species richness within the community, and includes seaside goldenrod (Solidago sempervirens), switch grass (Panicum virgatum), vanilla grass (Hierochloe odorata), necklace sedge (Carex hormathodes), red fescue (Festuca rubra), New York aster (Symphyotrichum novi-belgii), Virginia wild rye (Elymus virginicus), germander (Teucrium canadense), Canadian burnet (Sanguisorba canadensis), quack grass (Elymus repens), fresh-water cordgrass (Spartina pectinata), Scotch lovage (Ligusticum scothicum), and shore rush (Juncus arcticus).

Less frequent species in this community are bushy knotweed (Polygonum ramosissimum), exserted knotweed (Polygonum ramosissimum), prolific knotweed (Polygonum ramosissimum), coastal silverweed (Argentina egedii), white wood aster (Aster divaricatus), and small salt marsh aster (A. subulatus).

Plants often found on low natural levees include sea-blites (Suaeda spp.), seaside alkali-grass (Puccinellia maritima), and halberd-leaved orache (Atriplex prostrata). Along larger marsh creeks, levees several meters wide typically rise 5–15 cm (2–6") above the marsh. Areas along the upper edge of this community that are influenced by freshwater streams, ephemeral channeled runoff, or groundwater discharge often support brackish marsh communities.

Variants:
This community occurs in two distinct settings, forming two variants. The typic variant is more common than the shallow peat variant in New Hampshire.

1. Typic variant: As described above. This variant occurs in deeper organic soils in estuarine settings.

2. Shallow peat variant: This variant occurs as isolated patches or linear strands of salt-meadow cordgrass (Spartina patens) and other species in moderate to high-energy settings. Peat depth is shallow, often only a few inches deep. Substrate is bedrock, gravel, or cobble. Frequently occurs together with the mineral soil variant of low salt marsh.


Good examples
of this community can be seen at Sandy Point on the south shore of Great Bay at the Great Bay Discovery Center in Greenland/Stratham, the Salt Marsh Trail at the Urban Forestry Center in Portsmouth, Rye Harbor State Park (Rye), Berry Brook at the western entrance of Odiorne Point State Park (Rye), Hampton Marsh (Hampton/Hampton Falls/Seabrook), Lubberland Creek Preserve (Newmarket), Bellamy River Wildlife Sanctuary (Dover), Crommet Creek (Durham), and from the boat launch along the Squamscott River in Stratham. 

High salt marsh often occurs as part of a larger salt marsh system.


High salt marsh community along the Squamscott River south of Great Bay (photo by Ben Kimball for the NH Natural Heritage Bureau)
High salt marsh community (typic variant) along the Squamscott River south of Great Bay
(photo by Ben Kimball)

Spartina patens (salt meadow cord-grass) dominated high salt marsh at Hampton Marsh (photo by Ben Kimball for the NH Natural Heritage Bureau)
Salt meadow cord-grass (Spartina patens) dominated high salt marsh at Hampton Marsh
(photo by Ben Kimball)

high salt marsh at Hampton Marsh (photo by Ben Kimball)
extensive high salt marsh (typic variant) at Hampton Marsh (photo by Ben Kimball)

high salt marsh (shallow peat variant) at Odiorne Point State Park (photo by Ben Kimball)
high salt marsh (shallow peat variant) at Odiorne Point State Park (photo by Ben Kimball)

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