Natural Communities of NH -- Photo Guide

Coastal interdunal marsh/swale  (S1)



Coastal interdunal marsh/swales
are freshwater wetland communities that occur in shallow depressions between sand dunes in a portion of the state's only remaining dune system. These swales may be shrub or graminoid dominated and are likely very important to amphibians and other wildlife for breeding, food, and shelter. At one time, numerous swales likely existed as part of an extensive dune system that occurred in Seabrook and Hampton. 

Soils are typically seasonally flooded. A thin surface organic layer lies above sandy soils. 

Characteristic vegetation: Dominants vary from swale to swale and include large cranberry (Vaccinium macrocarpon) swales and shore rush (Juncus arcticus) swales. Marginal associates include purple chokeberry (Aronia prunifolia), winterberry (Ilex verticillata), poison ivy (Toxicodendron radicans), and marsh St. John’s-wort (Triadenum virginicum). Cattails may be present, and also invasive species such as purple loosetrife (as in the photo below).


In New Hampshire, the only good example of this community is at The Sands (Seabrook).

Coastal interdunal marsh/swale communities occur as part of larger coastal sand dune systems


Coastal interdunal marsh/swale amongst vegetated dunes at The Sands (photo by Ben Kimball for the NH Natural Heritage Bureau)
Coastal interdunal marsh/swale among vegetated dunes at The Sands (photo by Ben Kimball)

back to Natural Communities of NH Photo Guide