United States Department of Agriculture
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United States Department of Agriculture
Natural Resources Conservation Service
Ecological Site Description

Section l: Ecological Site Characteristics

Ecological Site Identification and Concept


Site stage: Provisional

Provisional: an ESD at the provisional status represents the lowest tier of documentation that is releasable to the public. It contains a grouping of soil units that respond similarly to ecological processes. The ESD contains 1) enough information to distinguish it from similar and associated ecological sites and 2) a draft state and transition model capturing the ecological processes and vegetative states and community phases as they are currently conceptualized. The provisional ESD has undergone both quality control and quality assurance protocols. It is expected that the provisional ESD will continue refinement towards an approved status.

Site name: Tidal Salt Low Marsh mesic very frequently flooded
/ Spartina alterniflora
( / smooth cordgrass)
Site type: Rangeland
Site ID: R144AY001CT
Major land resource area (MLRA): 144A-New England and Eastern New York Upland, Southern Part

Low Marsh Extent Map


MLRA 145, Connecticut Valley is based on the concept that glacial Lake Hitchock left finer sediments in the form of varved clays, silts, and fine sands in the middle of a larger and coarser-textured post-glacial environment. The upland areas are mainly comprised of glacial deposits (till and outwash) and/or loess overlying glacial lake sediments, with a mix of recent alluvium and organic residuum in the lower-lying areas directly surrounding the Connecticut River.
The tidal marsh ecological sites are located in the southern section of the MLRA, near the mouth of the Connecticut River along the Long Island Sound coast.

MLRA 144A, the New England and Eastern New York Upland, Southern Part is in the New England Upland section of the New England Province of the Appalachian Highlands Division. The area is nearly level to sloping lowlands on the edges of the valley. North to south running trap rock ridges break up the lowlands with hilly, steep areas. Elevation ranges from sea level to 330 feet (100 meters) in the lowlands and from 650 feet to 1,000 feet (200- 305 meters) on ridges.
The tidal marsh ecological sites are located in the south and eastern sections of the MLRA, near the Atlantic Ocean and Long Island Sound coasts.

MLRA 149B, Long Island-Cape Cod Coastal Lowland is in the Embayed section of the Coastal Plain Province of the Atlantic Plain Division (Fenneman & Johnson, 1946). It is part of the partially submerged coastal plain of New England. It is mostly an area of nearly level to rolling plains, but it has some steeper hills (glacial moraines). Ridges border the lower plains. Elevation generally ranges from sea level to 80 feet (0 to 25 meters), but it is as much as 410 feet (125 meters) in a few areas.
The tidal marsh ecological sites are located throughout the MLRA, near the Atlantic Ocean and Long Island Sound coasts.

Ecological Site Concept

Salt marshes are coastal wetlands that are alternately flooded and drained by salt water borne by oceanic tides. Salt marshes typically develop in sheltered environments in different geomorphic settings, typically coves, bays, behind barrier beaches, drowned valleys, and at the confluence of major rivers, where marshy peat and sediment can accumulate. As coastal landforms, tidal marshes are low in elevation and generally flat, although they can exhibit changes in microrelief. The climate depends upon latitude, but evidently with a strong maritime influence, producing cooler summers and warmer winters. Tidal marsh vegetation is poorly developed but highly productive. Few plant species can physiologically tolerate the high salinities, but those that do can flourish. The predominant vegetation form in the regularly flooded zone is the tidal salt “low marsh” appearing as different vegetation-forms reflecting changes in density and composition, Several different states occur where the vegetation and habitat conditions change dramatically, including a dieback/ or collapsed state and a tidally restricted state, impounded state, and filled state. In addition are 4 transition crossovers to other ecological sites: Tidal Brackish Wetland ecological site, Tidal Salt High Marsh ecological site, Tidal Salt Flats ecological site, and various Filled Nontidal ecological sites.

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