Of all the environments in the eastern United States, the tidal salt marsh might be the most unassumingly abundant with life. These vast, low-lying green landscapes sustain a rich diversity of life, and the food web relies largely on the foundation of the seemingly monocultural vegetation found within them. Inland habitats of the Coastal Plain are separated into multiple natural communities, for example, forests, river systems, and bogs/swamps, each having particular defining criteria based on soil type, hydrology, and elevation that give rise to very different plant communities. Each of these plant communities may be characterized by a species or assemblage of species such as an “oak/hickory forest”, but each has scores, if not hundreds, of species that fill the habitat from the treetop canopy to the forest floor. This is not the case in tidal marshes where each individual marsh zone is usually dominated by one or just a few plant species. The plants that are adapted to this zone experience changeable, but historically predictable, environmental conditions including continuous tidal fluctuations, so it is not surprising that fewer species of plants are suited to growing in these areas. In addition to having to adapt to a wide range of wet and dry conditions, these plants also had to adapt to salty waters. As a result, the different zones of marsh are readily identifiable even from aerial or satellite imagery based on the type and abundance of the plant species.
Aerial photo illustrating the transition from low marsh (dark brown vegetation) to high marsh (light green vegetation) to upland forest (darker green vegetation). Photo credit: Larisa Prezioso, Eastern Shore Land Conservancy
In the lower marsh, smooth cordgrass (Spartina alterniflora) is the dominant vegetation due to its ability to tolerate large changes in inundation and salinity. Smooth cordgrass has two forms, tall and short, that appear at slightly different depths of tidal inundation. These low spartina marshes are typically less prominent in the Mid-Atlantic, though they can cover substantial tidal areas along the coast to the north and south.
Snails perched on Spartina alterniflora in the “low marsh” zone. Photo credit: Sophia Seufert, USFWS
Salt pannes are areas within the marsh that typically have low vegetation cover due to high salt content and pools of water. Saltwort (Salicornia spp.), a well-known plant that is adapted to salt pannes, is edible and can be steamed, blanched, sauteed, or added fresh to a salad.
Salt panne with pooled water. Photo credit: Sophia Seufert, USFWS
Hummocks are elevated bumps in the marsh that protrude above the surrounding marsh and may contain a much higher diversity of plants, due to the more stable environmental conditions and less exposure to salt. Hummocks include species such as hightide bush (Baccharis halimifolia), marsh elder (Iva frutescens), and even trees such as eastern red cedar (Juniperus virginiana). These more densely vegetated hummocks can form along the edge of a creek or ditch alluding to the historic manipulation of these landscapes where hand dug sediment was left.
Iva frutescens growing on hummocks flanking a ditch. Photo credit: Sophia Seufert, USFWS
Of particular concern in the mid-Atlantic is the health and long-term viability of the upper or high marsh, which has been declining due to pressures from sea level rise, saltwater intrusion, ditching, and land development. This high marsh is where the main species of concern of the Marshes for Tomorrow project, the saltmarsh sparrow, lives and raises its young. The birds that nest in this zone depend on large expanses of salt hay (Spartina patens) that remain inundation-free for the breeding season. Due to the ecological importance of the high marsh and unique wildlife that depends on it, the Marshes for Tomorrow initiative will focus on maintaining the health of the plants and animals within the highmarsh zone.
Meadow of Spartina patens, the nesting plant for the Saltmarsh Sparrow. Photo credit: Sophia Seufert, USFWS
Explore this saltmarsh plant identification guide to learn more! https://www.saltmarshguide.org/guide/identification-guide/terrestrial-plants/
Marshes for Tomorrow (MfT) is an ambitious project led by Audubon mid-Atlantic and regional partners of the Delmarva Restoration and Conservation Network (DRCN) to identify, protect, and restore at least 25,000 acres of the most important tidal salt marsh habitat on Maryland’s Eastern Shore for saltmarsh sparrows. MfT is utilizing the most recent scientific analysis coupled with community input to select the areas to concentrate our efforts. If you would like to learn more about MfT or join one of our upcoming public meetings, please visit the MfT website at https://www.delmarvarcn.org/marshesfortomorrow.
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