Natural Community Systems -- Photo Guide

Alpine ravine / snowbank system

alpine ravine / snowbank system in Tuckerman Ravine (photo by Ben Kimball for the NH Natural Heritage Bureau)
Alpine ravine / snowbank system in Tuckerman Ravine (photo by Ben Kimball)

Alpine ravine / snowbank system in Tuckerman Ravine (photo by Ben Kimball for the NH Natural Heritage Bureau)
Alpine ravine / snowbank system in Tuckerman Ravine (photo by Ben Kimball)

 

Description: Alpine ravine/snowbank systems are distinguished from alpine tundra systems by the unique convergence of several natural communities that occur in high alpine ravines.  Alpine ravines have the largest occurrences and/or concentration of alpine herbaceous snowbank/rill, alpine ravine shrub thicket, black spruce - balsam fir krummholz, and montane landslide natural communities, in addition to alpine cliffs.  This system is most distinct in the major, high-elevation, cirque-like ravines with large snowpacks.  These occur on the eastern side of the Presidential Range and include Tuckerman Ravine, Huntington Ravine, and Great Gulf, though Oakes Gulf on the southern side also contains a distinct example.  These ravines have a classic bowl-shaped cirque headwall rimmed by alpine cliffs and rock slabs, divided by landslide and avalanche gullies with alpine rill streams or choked with talus.  High-elevation balsam fir forest extends up from the ravine bottom and onto the ravine side-slopes, becoming shorter and scrubbier as it transitions to krummholz, heath - krummholz, or other alpine/subalpine communities.  A few ravines have subalpine cold-air talus barrens at their base where late-melting ice under huge boulders supports stunted Picea mariana (black spruce) and a host of alpine plants well below treeline.  Alpine herbaceous snowbank/rill communities are found along steep and wet rocky gullies, at the bases of headwalls, and on the wet brows of the ravine above the headwall.  Alpine ravine/snowbank systems are less distinct in smaller and lower elevation ravines that have a higher proportion of black spruce/balsam fir krummholz and scrubby high-elevation balsam fir forest and smaller patches of the other diagnostic communities.

Species listed below are specific to snowbank, rill, ravine, or cliff habitats and thus are more frequent or abundant in this system than in the more well drained conditions of the alpine tundra system, although some are found in smaller isolated snowbank patches or along rills outside of ravine settings. 


Diagnostic natural communities:

      • Alpine herbaceous snowbank/rill
(S1)

      • Alpine ravine shrub thicket (S1S2)

      • Black spruce - balsam fir krummholz (S2S3)

      • Montane landslide barren and thicket (S3S4)

      • Alpine heath snowbank (S1S2)

      • Subalpine cold-air talus barren (S1)


Peripheral or occasional natural communities:

      • Labrador tea heath - krummholz (S2)

      • Subalpine sliding fen (S1)

      • Moist alpine herb - heath meadow (S1)

      • Sedge - rush - heath meadow (S1)



Landscape settings: high-elevation ravines, particularly those with distinct cirque headwalls

Soils: dry to wet, mostly acidic, somewhat poorly- to well-drained, shallow organic or organic-rich coarse mineral materials over rock; also bare talus and bedrock (outcrops, slabs, and cliffs); mixed mineral debris in landslide gullies and debris cones

Spatial pattern: small to large patch (50300+ acres), irregular and vertical-linear zonation

Physiognomy: sparsely vegetated, dwarf shrubland, herbaceous, krummholz, and tall shrub thicket

Distribution: Presidential Range of the White Mountains


Characteristic species:


Plants abundant and concentrated in alpine ravine/snowbank systems (snowbank, rill, ravine, and cliff habitats):

Shrubs
   Alnus viridis var. crispa (mountain alder)
   Vaccinium cespitosum (dwarf bilberry)
   Salix argyrocarpa (silver willow)
   Salix planifolia (tea-leaved willow)
   Spiraea septentrionalis (alpine meadow-sweet)

Herbs
   Solidago macrophylla (large-leaved goldenrod)
   Veratrum viride (false hellebore)
   Viola palustris (alpine marsh violet)
   Arnica lanceolata (arnica)
   Oxyria digyna (mountain sorrel)
   Epilobium hornemannii (Hornemann's willow-herb)
   Sibbaldia procumbens (sibbaldia)
   Saxifraga rivularis (alpine brook saxifrage)
   Saxifraga cernua (nodding saxifrage)
   Saxifraga aizoon var. neogaea (livelong saxifrage)


Associated natural community systems:  This system transitions to alpine tundra system on more well drained slopes and ridges above alpine ravines, and to high-elevation spruce - fir forest system at lower elevations.


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