Alpine ravine shrub thicket (S1S2)
Extensive alpine ravine shrub thickets are found on the lower slopes of Tuckerman Ravine, Great Gulf, and other large ravines on Mt. Washington. Winter snow accumulation can be substantial in these locations, especially on north-facing slopes. The community is dominated primarily by mountain alder and other deciduous shrubs. Herbaceous forbs are common in the understory. It forms on steep to nearly level rock, talus, and cobbly substrates, generally above 4,000 ft. elevation. Deep, late-melting snowpacks bury the community for much of the year and add a significant amount of moisture to the otherwise well-drained rocky soils. This community has not been sampled extensively, but is distinct and forms huge thickets in Tuckerman Ravine.
Characteristic Vegetation: Mountain alder (Alnus viridis ssp. crispa) forms dense thickets (>65% cover) in this community. alpine meadowsweet (Spiraea septentrionalis) or meadowsweet (Spiraea alba) is common, and silver willow (Salix argyrocarpa), Bartram's serviceberry (Amelanchier bartramiana), and other willows (Salix spp.) are occasional along streams. Lowland plants characteristic of alpine herbaceous snowbank/rill and high-elevation spruce - fir forest communities are present in low to moderate abundance. These include common hairgrass (Deschampsia flexuosa), northern lady fern (Athyrium filix-femina var. angustum), large-leaved goldenrod (Solidago macrophylla), intermediate wood fern (Dryopteris intermedia), mountain wood fern (Dryopteris campyloptera), and purple-stemmed aster (Symphyotrichum puniceum). Areas with less than about 65% mountain alder appear to have a more robust herb layer and are treated as shrubby examples of alpine herbaceous snowbank/rill communities.
A good example of this community can be seen in Tuckerman Ravine.
Alpine ravine shrub thickets frequently occur as part of a larger alpine ravine/snowbank system.
alpine ravine shrub thicket near the top of Great Gulf
(photo by Dan Sperduto)
alpine ravine shrub thicket occurs on the steep slopes Tuckerman Ravine (photo by Ben Kimball)
alpine ravine shrub thicket in Tuckerman Ravine (photo by Ben Kimball)
alpine ravine shrub thicket on the "floor" of Tuckerman Ravine on Mt. Washington (photo by Ben Kimball)
Tuckerman Ravine in winter. Under the snow, alpine ravine shrub thickets
occupy much of the lower, flatter portion of this scene (photo by Ben Kimball)
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