Natural Communities of NH -- Photo Guide

Red maple - lake sedge swamp  (S3)

Red maple - lake sedge swamps
occur around the margins of marshes on silty mineral soils with a thin muck layer. They are broadly distributed south of the White Mountains, and most abundant near the seacoast where silt soils are common. It is associated with perennial seepage and other minerotrophic areas on level to slightly sloping ground between uplands and open marshes. Some examples of this community are probably marshes succeeding to swamps. Red maple dominates the woodland canopy, while other tree species are occasional. A dense herbaceous understory is dominated by lake sedge, a tall and broad-leaved graminoid. The cover of lake sedge is high (25-70+%). This species reaches its greatest density in this community and in minerotrophic seepage marshes.

Soils are poorly to very poorly drained and have a shallow fibric organic horizon (<20 cm) over substrates of gleyed silt, silt loam, or clay (heavy mineral histic soils, some of marine origin). Soil water pHs are circumneutral. 

Characteristic Vegetation: Characteristic features include a woodland canopy of red maple (Acer rubrum) (25-60%) and a dense, tall layer of lake sedge (Carex lacustris). Other occasional trees include American elm (Ulmus americana) and swamp white oak (Quercus bicolor). A diverse assemblage of shrubs and herbs is typical, but lake sedge usually exceeds the cover of all other herbaceous species combined. A modest shrub layer commonly contains winterberry (Ilex verticillata), southeastern silky dogwood (Cornus amomum), northern arrowwood (Viburnum dentatum var. lucidum), nannyberry (Viburnum lentago), poison ivy (Toxicodendron radicans), and meadowsweet (Spiraea alba var. latifolia). The herb layer is diverse but has few species that exceed 1% cover. The few that may exceed 1% cover include sensitive fern (Onoclea sensibilis), tussock sedge (Carex stricta), bluejoint (Calamagrostis canadensis), and royal fern (Osmunda regalis). Other characteristic species found in low abundance include spotted touch-me-not (Impatiens capensis), white turtlehead (Chelone glabra), common water hemlock (Cicuta maculata), bulbiferous water hemlock (Cicuta bulbifera), dwarf raspberry (Rubus pubescens), and wood horsetail (Equisetum sylvaticum). Peat mosses (Sphagnum spp.) are typically absent or not abundant in these swamps (<5% cover), though seepage species such as Sphagnum squarrosum may be expected. The rare climbing hempweed (Mikania scandens) may be present.

Good examples of this community occur at Great Meadows (Exeter), Contoocook River (Peterborough), Great Bog (Portsmouth), and Turtle Pond (Concord).

Red maple - lake sedge swamps often occur as part of larger temperate minerotrophic swamp systems.

Red maple - lake sedge swamp at Turtle Pond (photo by Dan Sperduto for the NH Natural Heritage Bureau)
Red maple - lake sedge swamp at Turtle Pond
(photo by Dan Sperduto)

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