Natural Community Systems -- Photo Guide

Temperate minerotrophic swamp system

temperate minerotrophic swamp system at Paul Brook Swamp in the Seacoast Region (photo by Ben Kimball for the NH Natural Heritage Bureau)
temperate minerotrophic swamp system 
at Paul Brook Swamp in Newington (photo by Ben Kimball)


Description:  This is a relatively common red maple swamp system found in central and southern New Hampshire with well decomposed shallow peat or mineral soils, including classic seepage swamps and other more common minerotrophic swamp types.  This system occurs in relatively flat basins, with soils that range from shallow organic layers over silty or sandy mineral soils and apparent seepage influence to relatively shallow, well decomposed peat.  Measured pHs are typically in the 5s and 6s.  It is dominated by red maple (Acer rubrum), with lesser quantities of hardwoods like black ash (Fraxinus nigra) and yellow birch (Betula alleghaniensis) and occasional conifers, particularly hemlock (Tsuga canadensis).  Many of the species found in temperate peat swamps can also be found in this system, including southern and coastal species, but moderately to strongly minerotrophic conditions absent in more acidic peat swamps and indicative of this type are present (listed below).  Northern conifers, shrubs, and herbs of near-boreal swamps are absent or sparse.  The shrub layer is typically well developed, and the herb and bryophyte layer are well developed and diverse.  Sphagnum mosses are usually in relatively low abundance compared to temperate peat swamp systems, but can be abundant in particularly seepy locations.  These swamps support a substantial non-Sphagnum bryophyte layer.  Strongly sloping examples on seepy silty soils often can have a great deal of black ash, lake sedge (Carex lacustris), or skunk cabbage (Symplocarpus foetidus).  Shrubby openings are common in these swamps.  The red maple - sensitive fern swamp community is the most common swamp type in this system.  This system is often bordered by hemlock - cinnamon fern or red maple - red oak - cinnamon fern forests that are intermediate between swamp and upland forest.  Examples that transition to emergent marshes may contain seasonally flooded red maple swamps and those that transition to peatlands may contain red maple - Sphagnum basin swamps.

Diagnostic natural communities:

   • Red maple - sensitive fern swamp (S3S4)

   • Red maple - black ash swamp (S2)

   • Red maple - lake sedge swamp (S3)

   • Highbush blueberry - winterberry shrub thicket (S4)

Peripheral or occasional natural communities:

   • Hemlock - cinnamon fern forest (S4)

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

   • Red maple - Sphagnum basin swamp (S4) 

   • Red maple - elm - lady fern silt forest (S1S2)

   • Seasonally flooded red maple swamp (S4S5)

Landscape settings: depressional headwater basins and drainage ways; sloping mineral soils around open wetlands; pond and lake basins

Soils: mostly flat to moderately sloping mineral soils or shallow, well-decomposed peat or muck; moderately to strongly minerotrophic; pHs in the 5s and 6s; topogenous to soligenous, non-riparian

Spatial pattern: small to large patches (<5–50+ acres); circular-oval or irregular shaped; uniform, sometimes with shrubby openings or surrounding open wetlands

Physiognomy: forest to woodland with tall shrub openings

Distribution: widespread south of the White Mountains

Characteristic species:

Trees and shrubs
      Abundant species:
      Acer rubrum (red maple)
      Ilex verticillata (winterberry)
      Occasional to locally abundant species:
      Tsuga canadensis (hemlock)
      Betula alleghaniensis (yellow birch)
      Vaccinium corymbosum (highbush blueberry)
      Infrequent to locally abundant indicators of at least weakly minerotrophic conditions:
      Fraxinus nigra (black ash)
      Fraxinus americana (white ash)
      Lindera benzoin (northern spicebush)
      Ulmus americana (American elm)
      Alnus incana ssp. rugosa (speckled alder),
      Viburnum dentatum (northern arrowwood)
      Spiraea alba (eastern meadowsweet)
      Toxicodendron radicans (poison ivy)
      Toxicodendron vernix (poison sumac)
      Sambucus canadensis (common elderberry)
Lindera benzoin (northern spicebush)
      Viburnum lentago (nannyberry)
      Cornus sericea (red osier dogwood)
      Cornus amomum (southeastern silky dogwood)
      Rubus pubescens (dwarf raspberry)

Herbs and bryophytes
      Abundant or locally abundant indicators of at least weakly minerotrophic conditions:
      Onoclea sensibilis (sensitive fern)
      Carex lacustris (lake sedge)
      Carex stricta (tussock sedge)
      Infrequent to locally abundant indicators of at least weakly minerotrophic conditions:
      Impatiens capensis (spotted touch-me-not)
      Caltha palustris (marsh marigold)
      Viola spp. (violets)
      Geum rivale (purple avens)
      Symplocarpus foetidus (skunk cabbage)
      Hydrocotyle americana (water pennywort)
      Sphagnum squarrosum (peat moss)
      Mnium spp. (mosses) 

Associated natural community systems:  In larger swamp basins this system can transition into temperate peat swamp systems.  It also can transition into emergent marsh - shrub swamp systems.

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