Common (Translated Scientific) Name: Arctic Willow - (Alpine Willow, Snow Willow) / American Bistort Dwarf-shrubland

Colloquial Name: No Data Available

Hierarchy Level:  Association

Type Concept: This dwarf-shrub alpine association is known from the Rocky Mountains of Alberta, Montana and Wyoming. It occurs primarily as small patches, from the uppermost subalpine to the highest alpine elevations, from 1980 to 3231 m (6495-10,600 feet). It is mainly associated with receiving positions, toeslopes and lower to midslopes of gentle terrain. It occurs in mesic areas with slopes that range from flat to moderate (up to 50% grade), with all aspects represented. The type occurs predominantly in small, visually salient patches that appear as a continuous blanket of green due to high coverage of both the vascular and bryophyte components. The dwarf-shrub layer is commonly dominated by Salix arctica, Salix petrophila, or Salix nivalis. Dryas octopetala may be present or absent in the dwarf-shrub layer with up to 20% cover. Graminoids are present in all stands but are neither diverse nor in high quantities. Common species include Poa alpina and moist-site Carex spp. (Carex albonigra, Carex phaeocephala, and Carex nova). The herbaceous layer is dominated by forbs, most notably Polygonum bistortoides, but other forbs, including Polygonum viviparum, Geum rossii, Potentilla diversifolia, Oreostemma alpigenum, Solidago multiradiata, and Claytonia lanceolata, are often codominant. Other common species include Astragalus kentrophyta, Phlox pulvinata, Tetraneuris grandiflora, Arenaria congesta, Oxytropis deflexa, and Castilleja spp. Picea engelmannii seedlings may be present. This association most often grades to moist turf types or unequivocal snowbed communities (e.g., ~Carex nigricans Wet Meadow (CEGL001816)$$) or wet meadows (e.g., ~Deschampsia cespitosa - Caltha leptosepala Wet Meadow (CEGL001882)$$). Most other dwarf-shrub Salix spp.-dominated types occur on yet wetter sites; therefore, they should be recognized first in working keys.

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: This association is weakly supported by plot data, and almost no formal inventory has been conducted, though the authors of the type noted it to be common in some mountain ranges other than those in which it was sampled for classification purposes. This type has not been crosswalked with several other similarly named associations (~Salix arctica / Geum rossii Dwarf-shrubland (CEGL001430)$$ [Colorado], Salix arctica / Polygonum viviparum Dwarf-shrubland Association (no equivalent in USNVC) [Wyoming], ~Salix arctica - Salix nivalis Dwarf-shrubland (CEGL001432)$$ [New Mexico], as well as Salix arctica-dominated snowbed communities from the Canadian Rockies that appear, at least superficially, to be comparable in vegetation and environment. Until this crosswalk is completed this association should be considered of questionable taxonomy and may be more common than the global rank indicates. In addition, plot work in Waterton Lakes National Park, Alberta, and in Grand Teton National Park included stands dominated by Salix nivalis or Salix petrophila rather than Salix arctica. Stands dominated by Salix petrophila (= Salix arctica ssp. petraea) and Salix arctica can stay together, as these are very closely related taxa, but stands dominated by Salix reticulata may be better served in their own association.

Similar NVC Types: No Data Available

note: No Data Available