Alpine herbaceous snowbank/rill
Alpine herbaceous snowbank/rill (S1)
Alpine herbaceous snowbank/rill communities occupy wet, lee positions under late-melting snowbanks. They are most abundant above treeline on the lips, headwalls, and gullies of the big ravines in the Presidential Range, but they are also found in scattered patches on higher slopes along streams and in seeps, and in the lee of moist outcrops. Late snow melt shortens an already brief growing season, but allows alpine plants to avoid spring frosts, and as a result lowland forbs are present among the higher elevation species.
Characteristic Vegetation: Large-leaved goldenrod (Solidago macrophylla), dwarf bilberry (Vaccinium cespitosum), false hellebore (Veratrum viride), bluets (Houstonia caerulea), bluejoint (Calamagrostis canadensis), and mountain avens (Geum peckii) are among the many species that distinguish this diverse community. It also harbors a large number of rare, wet-site alpine species including hairy arnica (Arnica lanceolata) and tea-leaved willow (Salix planifolia).
Variants: Three variants are described:
1. Typic variant:
This peaty expression of the community is the typic variant described above. It is generally wet for much of the growing season. Frequent plants include peat mosses (Sphagnum spp.), mountain avens (Geum peckii), large-leaved goldenrod (Solidago macrophylla), bluejoint (Calamagrostis canadensis), false hellebore (Veratrum viride), bluets (Houstonia caerulia), common hairgrass (Deschampsia flexuosa), tussock bulrush / a.k.a. deer's hair sedge (Trichophorum cespitosum), dwarf bilberry (Vaccinium cespitosum), purple-stemmed aster (Aster puniceus), and long beech fern (Phegopteris connectilis). Numerous rare species occur in this variant.
2. Tea-leaved willow - alpine herb variant:
This variant lacks many of the lowland herbs and peat mosses found in the other two variants. Non-Sphagnum bryophytes are abundant, however. Soils are moderately well to well-decomposed, seepy peats along or near perennial streams in relatively exposed snowbank settings (e.g., in the Alpine Garden). It does share several species with one or both of the other two variants, including large-leaved goldenrod, mountain avens, false hellebore, bluejoint, and tussock bulrush, but is differentiated by the presence of tea-leaved willow, viviparous knotweed, and Boott’s rattlesnake-root. Numerous other alpine plants may be present. This variant is transitional to less wet but still mesic areas, further from rills, that are described as the moist alpine herb - heath meadow community.
3. Mesic lowland herb variant:
This variant has more well drained mineral soils (A horizons) with mesic conditions in mid to late summer compared to the other two variants that are seepy or saturated for much of the growing season. Herbs most often found in lowlands dominate along with only a few alpine plants. Dominants include large-leaved goldenrod (Solidago macrophylla), common hair-grass (Deschampsia flexuosa), dwarf bilberry (Vaccinium cespitosum), bluebead lily (Clintonia borealis), and bunchberry (Cornus canadensis). Bigelow's sedge (Carex bigelowii) and alpine bilberry may also be present.
Good examples of the alpine herbaceous snowbank/rill community can be seen on Mt. Washington at sites such as the Alpine Garden and in Tuckerman Ravine, Oakes Gulf, and Great Gulf.
This community frequently occurs along with other alpine communities as part of a larger alpine tundra system, and also sometimes within alpine ravine/snowbank systems.
1. alpine herbaceous snowbank/rill at Edmands Col in the Presidential Range (photo by Ben Kimball)
2. alpine herbaceous snowbank/rill in the Alpine Garden on Mt. Washington (photo by Dan Sperduto)
1. Alpine snowbank near Dingmaul Rock on Mt. Jefferson (photo by Ben Kimball)
2. Alpine rill at Raymond Cataract on Mt. Washington (photo by Ben Kimball)
alpine herbaceous snowbank/rill in the Great Gulf ravine
(photos by Dan Sperduto for the NH Natural Heritage Bureau)
Arnica lanceolata in bloom in a rill in Tuckerman Ravine
(photo by Ben Kimball)