Sea-Level Fen State Rank: S1 - Critically Imperiled

Sea-level Fen State Rank: S1 - Critically Imperiled

are most identifiable by Sea-level Fens are herbaceous/ location: they occupy the graminoid peatlands that occur at the interface between estuarine upland edges of ocean tidal marshes; marshes and upland. The combination of upland freshwater Saltmarsh straw-sedge, seepage and periodic brackish overwash saltmarsh spike-sedge, and produces a plant community of mixed saltmarsh (or Olney's) freshwater and estuarine species; threesquare are diagnostic of Sea-level Fens. Twig-sedge white beak-sedge, swamp-rose, common at the edges of salt marshes is threesquare, poison ivy, marsh St. John's- also used as an indicator of wort, and large cranberry. Occasional Sea-level Fens. Acidic A very narrow Sea-level Fen, with twig sedge. shrubs include poison sumac, swamp Graminoid Fens (AGF) are Photo: Patricia Swain, NHESP. azalea, bayberry, groundsel-tree, and differentiated by the eastern red cedar. dominance of graminoid and herbaceous wetland and upland animals. Songbirds Description: Sea-level Fens are species and lack of extensive shrubs. can use shrubby parts of the community herbaceous/graminoid peatlands just Differentiating from Related Threeway sedge and buckbean are as nesting or foraging habitat. above normal high tide at the upland edge characteristic of wet, nutrient enriched Communities: Natural communities Examples with Public Access: of estuarine tidal marshes. Periodic on acidic peatlands all occur on sphagnum edges of AGF. Interdunal Marsh/Swales None of the known sites are entirely in brackish overwash mixed with freshwater peat. The depth, density, and strength of occur as part of a coastal dune system. conservation ownership. If visited, care seepage from sandy uplands produces a the underlying peat control the structure They are graminoid- or shrub-dominated should be taken not to create trails across plant community of mixed freshwater and and composition of each type of peatland communities occurring in shallow basins the easily damaged peat surface. estuarine species on sedgy peat over sand community through the extent that plants (swales) between dunes. Some are fen- or gravel. Sea-level Fens are near their growing on it are isolated from nutrients like with cranberries and sedges growing northern limits in Massachusetts and are carried by ground water. Sea-level Fens on shallow peat, but occurring in dune better developed to the south where they systems is the defining characteristic. include more specialized species. Acidic Shrub Fens (ASF) are composed primarily of low-growing, interwoven Characteristic Species: Sphagnum shrubs. Dense water-willow and sweet moss commonly forms the peat mat in all gale are indicative and characteristic. ASF acidic peatlands – mixed with sedge peat are wetter with a less well-developed in Sea-level Fens. Three diagnostic sphagnum mat than other acidic peatlands. species are identified in regional descriptions: saltmarsh straw-sedge, Habitat for Associated Fauna: saltmarsh spike-sedge, and saltmarsh (or Few animals are likely to differentiate Olney's) threesquare. Other common between Sea-level Fens and other species include New York aster, spatulate- wetlands: species sensitive to salt would leaved sundew, Canada rush, pondshore- avoid Sea-level Fens during and after salt rush, swamp-candles, common reed Sea-level Fen with invading phragmites. Photo: water incursions, otherwise the fens Sea-level Fen with phragmites along tidal (native and invasive exotic subspecies), Patricia Swain, NHESP. would be part of the habitat of mobile streams. Photo: Patricia Swain, NHESP;

From: Classification of Natural Communities of Massachusetts htthttpp://www;mass;gov/nhesp/://www;mass;gov/nhesp/ Updated: 2016 Natural Heritage & Endangered Species Program, Division of FishFisheeriesries & Wildlife, 1 Rabbit Hill Rd;, Westborough, M! 01581 (508) 389-6360