Red maple - Sphagnum basin swamp (S4)
Red maple - Sphagnum basin swamps are common thoughout central and southern New Hampshire. The canopy is strongly dominated by red maple, though other tree species are commonly present. There is a well-developed shrub layer and a significant amount of peat moss. This is a common type of “red maple swamp” that occurs in perched basins of till landscapes or other low, flat areas with small watersheds (typically only 1/4 to 1 square mile or less). While they are influenced by seasonal subsurface and ephemeral runoff from surrounding uplands, there are typically no perennial streams running into or through the basins and there is minimal influence of groundwater. Softwoods are absent or in low abundance, the tall shrub and herb layers are moderately light to dense, and peat mosses (Sphagnum spp.) form a moderately patchy to dense ground layer. Hummock and hollow topography is well developed.
Soils are acidic, nutrient-poor, very poorly drained histosols (deep peat or muck >40 cm) or poorly to very poorly drained histic epipedons (O horizons are generally <20 cm). Although soils are generally saturated and have limited lateral movement of water, there is seasonal fluctuation resulting both from upland runoff in the spring and from evapotranspiration over the course of the growing season.
Characteristic vegetation: The tree canopy is dominated by red maple (Acer rubrum). Other tree species that may be sub-dominant to occasional include yellow birch (Betula alleghaniensis), hemlock (Tsuga canadensis), Pinus strobus (white pine), and red spruce (Picea rubens). Swamps dominated by red spruce are considered red spruce swamps. Overstory hemlock and white pine cover increases in somewhat more well-drained swamps. Black gum (Nyssa sylvatica) may also be present, but only in low abundance; a greater abundance of black gum would indicate the black gum - red maple basin swamp community.
The shrub layer usually contains significant amounts of some combination of highbush blueberry (Vaccinium corymbosum) and winterberry (Ilex verticillata) as primary dominants, with lesser amounts of mountain holly (Nemopanthus mucronatus), northern arrowwood (Viburnum dentatum var. lucidum), smooth winterberry (Ilex laevigata), meadowsweet (Spiraea alba), leatherleaf (Chamaedaphne calyculata), and the short shrubs sheep laurel (Kalmia angustifolia) and bristly dewberry (Rubus hispidus). The herbaceous layer typically contains a significant component of cinnamon fern (Osmunda cinnamomea) with lesser quantities of other herbs. Three-seeded sedge (Carex trisperma var. trisperma), marsh fern (Thelypteris palustris var. pubescens), common water horehound (Lycopus uniflorus), follicled sedge (Carex folliculata), and silvery sedge (C. canescens) are frequently present in low abundance. Upland herbs may occupy hummocks; these species include wild sarsaparilla (Aralia nudicaulis), goldthread (Coptis trifolia), and wintergreen (Gaultheria procumbens).
Peat mosses (Sphagnum spp.) are usually dominant or abundant in hollows and on lower sides of hummocks and include Sphagnum fallax, S. girgensohnii, and S. papillosum, among others. Wetter hollows in somewhat open swamps may have a greater abundance of species such as silvery sedge and wild calla (Calla palustris).
Good examples of this community occur at
Black gum - red maple basin swamps often occur as part of temperate peat swamp systems and coastal conifer peat swamp systems, and occasionally as part of temperate minerotrophic swamp systems.
Red maple - Sphagnum basin swamp at Northwood Meadows State Park
(photo by Dan Sperduto)
Red maple - Sphagnum basin swamp at Pisgah State Park (photo by Ben Kimball)
Red maple - Sphagnum basin swamp near Pawtuckaway State Park
(photo by Dan Sperduto)