Natural Communities of NH -- Photo Guide

Coastal shoreline strand/swale  (S2)

Coastal shoreline strand/swales
are sparsely vegetated upper intertidal communities that occur along protected estuarine shorelines at the transition from estuarine to upland habitats, particularly along muddy or rocky intertidal shores and the landward edge of salt marshes. It also occurs in backdune sandy depressions and channels bordering salt marshes. It can form either large patches or narrow strands. It often occurs along the strand line, linear heaps of decaying seaweed and herbaceous plants sheered off and deposited by tides and winter ice. Insects, arthropods, shore birds, and aquatic life use the plant stems and other detritus covering much of the ground surface of the strand/swale for food and shelter. 

The substrate consists of fine to coarse soils or various types of bedrock including those of the Rye Formation. The community is flooded less than daily.

Characteristic vegetation:
A sparse cover (typically <25%) of halophytic herbs consists of seabeach sand-spurrey (Spergularia marina), common glasswort (Salicornia europaea), southern sea-blite (Suaeda linearis), sea lavender (Limonium carolinianum), and seaside alkali-grass (Puccinellia maritima). Infrequent species include halberd-leaved orach (Atriplex prostrata) and other sea-blites (Suaeda spp.). Spike grass (Distichlis spicata) and salt-meadow cordgrass (Spartina patens) may be present in sandy areas. Other vascular plants often can be found along the upland border including sea-rocket (Cakile edentula), coast-blite goosefoot (Chenopodium rubrum), and knotweeds (Polygonum spp.). Rare species that may be found along the strand line are sea-chickweed (Honckenya peploides) and dwarf glasswort (Salicornia bigelovii). Plant stems and other detritus often cover much of the substrate surface.

This upper intertidal community is distinguished from intertidal rocky shores and intertidal flats by the presence of vascular plants, the absence or very sparse cover of rooted macroalgae, and less frequent tidal flooding. It is equivalent to the “drift-line community” found between the salt marsh and dunes at The Sands (Seabrook) as described by Dunlop et al. (1983).

Good examples of this community occur at Great Bay National Wildlife Refuge (Newington) and Sandy Point (Stratham).

Coastal shoreline strand/swales sometimes occur as part of a larger sparsely vegetated intertidal system.

coastal shoreline strand/swale along the south shore of Great Bay (photo by Bill Nichols)

coastal shoreline strand/swale along the shore of Great Bay (photo by Ben Kimball for the NH Natural Heritage Bureau)
coastal shoreline strand/swale along the east shore of Great Bay (photo by Ben Kimball)

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