Natural Community Systems -- Photo Guide

Temperate peat swamp system

temperate peat swamp system at Fox State Forest in Hillsborough (photo by Ben Kimball for the NH Natural Heritage Bureau)
temperate peat swamp system at Fox State Forest in Hillsborough (photo by Ben Kimball)


Description:  This system corresponds to acidic, oligotrophic peatlands in central and southern New Hampshire dominated by Acer rubrum (red maple) with variable amounts of conifers and other hardwoods.  Picea rubens (red spruce) is a common but minor associate, but otherwise northern conifers are absent or sparse, particularly in southern New Hampshire.  The tall shrub layer is well developed and almost always dominated by Vaccinium corymbosum (highbush blueberry) and Ilex verticillata (winterberry).  An abundance of Sphagnum spp. (peat mosses), Osmunda cinnamomea (cinnamon fern), and other herbs are characteristic.  It is also characterized by oligotrophic to weakly minerotrophic conditions, and therefore lacks species indicative of temperate minerotrophic swamps, such as Onoclea sensibilis (sensitive fern), Toxicodendron radicans (climbing poison ivy), Lindera benzoin (northern spicebush), and Fraxinus nigra (black ash), though these are sometimes found around the margins.  The core community is red maple - Sphagnum basin swamp, which is usually a peatland (>40 cm organic matter) but sometimes occurs on mineral soils with a histic epipedon (shallow organic layer less than 40 cm) where there may be more seasonal water fluctuations than in deep peat settings.  Mineral histic examples may occupy the entire swamp basin, or more commonly just the swamp areas marginal to uplands where organic accumulation is less.  The system is sometimes found in association with open peatland systems, but may also occur by itself.  Measured pHs are generally less than 5.3 (as low as 3.7), although pH and trophic levels can be higher around the system margins where there is often a shift in natural community type.  More southern or low elevation examples are more likely to contain species with coastal plain or southern distributions.  Patches of tall shrub fens (<25% tree cover) are common as part of the swamp mosaic; where these tall shrub fens become extensive, they may be best considered part of an adjacent open peatland system.  The transition to upland forests in this swamp system is often marked by a border of hemlock - cinnamon fern forest or red maple - red oak - cinnamon fern forest.

Diagnostic natural communities:

   • Red maple - Sphagnum basin swamp (S4)

   • Black gum - red maple basin swamp (S1S2)

   • Swamp white oak basin swamp (S1)

   • Highbush blueberry - winterberry shrub thicket (S4)

   • Highbush blueberry - mountain holly wooded fen (S3S4)

   • Winterberry - cinnamon fern wooded fen (S4)

Peripheral or occasional natural communities:

   • Hemlock - cinnamon fern forest (S4)

   • Red maple - red oak - cinnamon fern forest (S3S4)

   • Red maple - sensitive fern swamp (S3S4)

   • Seasonally flooded red maple swamp (S4S5) 

   • Red spruce swamp (S3)

Landscape settings: closed or stagnant, open headwater basins with limited drainage, often in depressions in glacial outwash or ice-contact deposits or lake or pond basins away from the influence of lake water

Soils: deep, moderately well decomposed peat; oligotrophic to weakly minerotrophic; pHs generally less than 5; topogenous

Spatial pattern:  small to large patch (<5 - 50+ acres), circular to irregular shape; uniform or forming exterior zone around open peatlands, sometimes in mosaics with more open peatlands

Physiognomy: forest to woodland with tall shrub patches

Distribution: found in central and southern New Hampshire

Characteristic species:
Trees and shrubs
      Abundant species:
      Acer rubrum (red maple)
      Vaccinium corymbosum (highbush blueberry)
      Ilex verticillata (winterberry)
      Occasional to locally abundant species (broad distribution):
      Picea rubens (red spruce)
      Tsuga canadensis (hemlock)
      Betula alleghaniensis (yellow birch)
      Nemopanthus mucronatus (mountain holly)
      Kalmia angustifolia (sheep laurel)
      Occasional to locally abundant species (restricted to coastal or southern NH; absent from near-boreal swamps):
      Nyssa sylvatica (black gum)
      Quercus bicolor (swamp white oak)
      Clethra alnifolia (sweet pepperbush)
      Ilex laevigata (smooth winterberry)
      Rhododendron viscosum (swamp azalea)
      Rhododendron maximum (giant rhododendron)
      Kalmia latifolia (mountain laurel)

Herbs and bryophytes
      Osmunda cinnamomea (cinnamon fern)
      Sphagnum spp. (peat mosses)
Occasional to locally abundant (broad distribution):
      Carex trisperma var. trisperma (three-seeded sedge)
      Thelypteris palustris (marsh fern)
      Lycopus uniflorus (common water horehound)
      Carex folliculata (follicled sedge)
      Carex canescens ssp. canescens (silvery sedge)
Occasional to locally abundant (coastal or southern distribution):
      Thelypteris simulata (Massachusetts fern)
      Woodwardia virginica (Virginia chain fern)
      Woodwardia aereolata (netted chain fern)
      Sphagnum torreyanum (peat moss)

Associated natural community systems:  This swamp system may be found around some poor level fen/bog systems and kettle hole bog systems, and in association with coastal conifer peat or temperate minerotrophic swamp systems, particularly in larger swamp systems that encompass a broad range of wetland conditions.  This system transitions to red spruce swamps at moderate elevations.

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