Natural Community Systems -- Photo Guide

Black spruce peat swamp system

black spruce peat swamp system in Lancaster (photo by Ben Kimball for the NH Natural Heritage Bureau)
black spruce peat swamp system in Lancaster (photo by Ben Kimball)


Description:  This system consists of acidic, nutrient-poor, wooded peatlands.  They are dominated by boreal conifers and heath shrubs, particularly Picea mariana (black spruce) and to a lesser extent Larix laricina (eastern larch) and other conifers.  The main community is black spruce swamp.  This community often surrounds open peatlands.  It can also dominate wooded (closed canopy) peatland basins.  Black spruce swamp systems occur on moderately to very deep peats.  Black spruce dominated areas on peat sometimes transitions to acidic northern white cedar swamps on peat or red spruce swamps on mineral soil, or northern white cedar - balsam fir swamp on minerotrophic peats.  These are acidic peatlands, typically with pHs in the high 3s to mid-4s, but occasionally higher in weakly minerotrophic swamps where eastern larch is in greater abundance.  Patches of tall shrub peatland thickets (fens with <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.

Diagnostic natural communities:

      • Black spruce swamp (S3)

      • Larch - mixed conifer swamp (S3)

      • Acidic northern white cedar swamp (S1)

      • Highbush blueberry - mountain holly wooded fen (S3S4)

      • Alder wooded fen (S3S4)

Peripheral or occasional natural communities:

      • Red spruce swamp (S3)

      • Northern white cedar - balsam fir swamp (S2)

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

Soils: deep, moderately well decomposed peat; oligotrophic to weakly minerotrophic; pHs generally in 3s to mid 4s, occasionally higher; topogenous

Spatial pattern: small to large patch (5100+ acres), occasionally extensive; circular to irregular shape, often as exterior zone around open peatlands or uniform, sometimes in mosaics with more open peatlands;

Physiognomy: forest to woodland and tall shrub

Distribution: broadly distributed in central and northern New Hampshire, much less common in lowland southern New Hampshire

Characteristic species:
Black spruce - larch swamp:
Trees and shrubs
      Picea mariana (black spruce) -- dominant
      Occasional to locally abundant:
      Larix laricina (eastern larch)
      Picea rubens (red spruce)
      Abies balsamea (balsam fir)
      Nemopanthus mucronatus (mountain holly)
      Viburnum nudum var. cassinoides (witherod)
      Lyonia ligustrina (male berry)

Dwarf shrubs
      Ledum groenlandicum (Labrador tea)
      Kalmia angustifolia (sheep laurel)
      Rhododendron canadense (rhodora)
      Vaccinium myrtilloides (velvet-leaf blueberry)
      Gaultheria hispidula (creeping snowberry)
      Cornus canadensis (bunchberry)
      Coptis trifolia (goldthread)

      Carex trisperma var. trisperma (three-seeded sedge)
      Osmunda cinnamomea (cinnamon fern)

      Sphagnum spp. (peat mosses)

Associated natural community systems:  This system is often found in association with poor level fen/bog systems, kettle hole bog systems, and lowland spruce - fir forest/swamp systems.  When this system surrounds an open bog or fen system, the two communities that typically mark the transition to open peatland system are leatherleaf - black spruce bog and highbush blueberry - mountain holly wooded fen.  The frequency and size of this system generally diminishes to the south in New Hampshire where temperate or coastal conifer peat systems are more common, and where black spruce swamps usually form narrow borders around bogs.

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