Natural Community Systems -- Photo Guide

Montane sloping fen system

montane sloping fen system on Whitewall Mtn. (photo by Dan Sperduto for the NH Natural Heritage Bureau)
montane sloping fen system on Whitewall Mountain (photo by Dan Sperduto) 

Description: This peatland system is weakly to moderately minerotrophic and forms nearly level to demonstrably sloping soligenous peat mats in the White Mountains at moderate to high elevations (above 2,400 ft.). Slopes are frequently up to 10 degrees, with a maximum of about 20 degrees. This system consists of montane sloping fen communities that occur in a mosaic with montane alder - heath shrub thickets and montane heath woodlands. These three communities (respectively) range from very poorly drained, shallow peat over cryic, silty gravel, to somewhat poorly drained shallow peat over bedrock or silty gravel. Peats are well decomposed, and hummock - hollow topography is moderately well to poorly developed. Measured pHs range from 4.2 to 6.2 (average 5.3). Portions of some montane sloping fen systems are associated with headwater drainage areas formerly impounded by beavers that were abandoned decades ago and have subsequently filled in with organics.

The key diagnostic natural community of this system, montane sloping fen, is dominated by graminoids or graminoids and shrubs, and is the only known fen in the state or region that is dominated by a grass. Calamagrostis pickeringii (Pickering’s reed bent-grass) on average contributes about 5% cover, and Carex wiegandii (Wiegand’s sedge) is frequent (both are state and regionally rare). Numerous other northern poor and medium fen plants are present (listed below).

Diagnostic natural communities:

      • Montane sloping fen (S1)

      • Montane alder - heath shrub thicket (S1?)

      • Montane heath woodland (S2)

Landscape settings: moderate- to high-elevation (above 2,400 ft.) valley bottoms and adjacent gently sloped mountain side-slopes; occur on definite soligenous slopes, shallow level depressions, and small drainage-ways associated with old beaver dams

Soils: shallow, well-decomposed peat; often on glacial lake bed or other silty-gravelly mineral deposits; weakly to moderately minerotrophic; pHs average 5.3 (4.2 to 6.3); soligenous and topogenous

Spatial pattern: small to large patch (<5 - 50+ acres); oval to irregularly amoeboid or linear shapes, irregular zonation

Physiognomy: graminoid - moss lawns, graminoid - shrub, tall shrub, sparse woodland and woodland

Distribution: found above 2,400 ft. in the White Mountains

Characteristic species:
Montane sloping fen:
      Calamagrostis pickeringii (Pickering's bluejoint)
      Carex wiegandii (Wiegand's sedge)
      Carex echinata (prickly sedge)
      Carex pauciflora (few-flowered sedge)
      Carex oligosperma (few seeded sedge)
      Solidago purshii (Pursh's goldenrod)
      Veratrum viride (false hellebore)
      Platanthera clavellata (small green woodland orchid)
      Drosera rotundifolia (round-leaved sundew)
      Eriophorum virginicum (tawny cotton-grass)

      Chamaedaphne calyculata (leather-leaf)
      Kalmia polifolia (bog laurel)
      Ledum groenlandicum (Labrador-tea)
      Rhododendron canadense (rhodora)
      Nemopanthus mucronatus (mountain holly)

Lowland peatland plants are absent, including:
      Vaccinium corymbosum (highbush blueberry)
      Gaylussacia baccata (black huckleberry)
      Ilex verticillata (winterberry)
      Woodwardia virginica (Virginia chain fern)

Associated natural community systems:  These systems are often set in a matrix of lowland spruce - fir forest/swamp systems in valley bottoms in the mountains, which sometimes include montane black spruce - red spruce forests.

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