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A3178 Dryas integrifolia - Dryas octopetala - Arctostaphylos uva-ursi Rocky Mountain Fell-field Dwarf-shrubland Alliance

Type Concept Sentence: This Rocky Mountain alpine alliance is characterized by an open to dense dwarf-shrub layer dominated by Dryas octopetala mats or, less commonly, Dryas integrifolia or Arctostaphylos uva-ursi that may extend down subalpine slopes. It has been reported from alpine habitats throughout the Rocky Mountain cordillera and alpine areas of high plateaus and ranges in the Colorado Plateau and Great Basin.

Common (Translated Scientific) Name: Entireleaf Mountain-avens - Eight-petal Mountain-avens - Kinnikinnick Rocky Mountain Fell-field Dwarf-shrubland Alliance

Colloquial Name: Rocky Mountain Mountain-avens - Kinnikinnick Fell-field Dwarf-shrubland

Hierarchy Level:  Alliance

Type Concept: This Rocky Mountain alpine alliance is characterized by an open to dense, often patchy dwarf-shrub layer dominated by Dryas octopetala mats or, less commonly, Dryas integrifolia or Arctostaphylos uva-ursi that may extend down subalpine slopes. Dwarf Salix spp. can be present to codominant. Scattered Dasiphora fruticosa ssp. floribunda and Juniperus communis may also be present. The herbaceous layer is variable, ranging from sparse to moderate cover, sometimes forming a patchy turf. Species diversity ranges from depauperate to diverse, dominated by graminoids or forbs. Carex species are often dominant, especially Carex elynoides and Carex rupestris, but also Carex albonigra, Carex nardina, and Carex scirpoidea. Other graminoids include Danthonia intermedia, Festuca brachyphylla, Kobresia myosuroides, Luzula spicata, Poa alpina, and Trisetum spicatum. Cushion plants such as Minuartia obtusiloba, Oxytropis borealis var. viscida, Oxytropis campestris, Oxytropis sericea, or Polygonum viviparum are common on drier sites. Moss and lichen cover is high on some plots (>50%). This alliance has been reported from alpine habitats throughout the Rocky Mountain cordillera and alpine areas of high plateaus and ranges in Colorado Plateau and Great Basin. Stands occur well above upper treeline on mountain ridges, fell-fields and other gentle to steep exposed slopes where snow blows off or melts relatively early. Elevations vary greatly with latitude, ranging from 2300 to 3900 m and extending down to 1700 m on dry ridges in northwestern Montana. Stands occur on all aspects. Soils are poorly developed, well- to rapidly drained and skeletal with a gravelly surface because of the windswept, exposed nature of these sites.

Diagnostic Characteristics: This alpine, fell-field alliance is characterized by a dwarf-shrub layer dominated by diagnostic species Dryas octopetala, Dryas integrifolia, or Arctostaphylos uva-ursi. The herbaceous layer is variable, ranging from sparse and to moderate cover with high to low species diversity dominated by graminoids or forbs. Carex species are often dominant. Moss and lichen cover is high on some plots (>50%).

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: This alliance needs to be compared to those from ~North Pacific Alpine-Subalpine Dwarf-Shrubland & Heath Group (G317)$$ and ~Vancouverian-Rocky Mountain Subalpine-Alpine Snowbed, Wet Meadow & Dwarf-Shrubland Group (G520)$$.

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: Vegetation in this alliance is characterized by an open ground layer of dwarf-shrubs, which form a discontinuous heath-like matrix less than 0.2 m in height. Upright or cushion-forming forbs are usually scattered through the dwarf-shrub stands. Scattered cespitose graminoids may also be common. Frost heaving usually results in patterns of alternating vegetation and bare ground.

Floristics: This Rocky Mountain alpine alliance is characterized by an open to dense, often patchy dwarf-shrub layer dominated by Dryas octopetala mats or, less commonly, Dryas integrifolia or Arctostaphylos uva-ursi that may extend down subalpine slopes. Dwarf Salix spp. can be present to codominant, including Salix reticulata, Salix arctica, or Salix nivalis. Scattered Dasiphora fruticosa ssp. floribunda and Juniperus communis may also be present. If present, the herbaceous layer is variable, ranging from sparse and to moderate cover, sometimes forming a patchy turf. Species diversity ranges from depauperate to diverse, dominated by graminoids or forbs. Carex species are often dominant, especially Carex elynoides and Carex rupestris, but also Carex albonigra, Carex nardina, and Carex scirpoidea ssp. pseudoscirpoidea (= Carex pseudoscirpoidea). Other graminoids include Danthonia intermedia, Festuca brachyphylla, Kobresia myosuroides, Luzula spicata, Poa alpina, and Trisetum spicatum. Cushion plants such as Minuartia obtusiloba, Oxytropis borealis var. viscida (= Oxytropis viscida), Oxytropis campestris, Oxytropis sericea, or Polygonum viviparum are common on drier sites. Other higher constancy species include Androsace chamaejasme, Artemisia scopulorum, Geum rossii, Lupinus sericeus, Lloydia serotina, Polygonum bistortoides, Rhodiola rosea, Saxifraga oppositifolia, Silene acaulis, Smelowskia calycina, Solidago multiradiata, and Zigadenus elegans. Moss and lichen cover is high on some plots (>50%).

Dynamics:  This alliance is associated with frigid, excessively drained, skeletal soils which are strongly influenced by frost heaving and needle ice formation (Bamberg and Major 1968). Bamberg and Major (1968) describe soil and vegetation movements of several centimeters in a single season due to frost churning. A net movement in the downslope direction, even on mild slopes (4-10%), occurs over time.
Environmental Description:  This Rocky Mountain alpine dwarf-shrubland alliance occurs on mountain ridges, fell-fields and other gentle to steep exposed slopes where snow blows off or melts relatively early. The climate is cold and snowy with severe winds, snow abrasion, and a short growing season. Sites are relatively dry, mostly subxeric to submesic. It occurs predominantly in alpine environments (well above treeline); actual elevations vary from 3370 to 3900 m in Colorado (Hess 1981), 2300 to 3145 m in southwestern Montana and western Wyoming (Bamberg and Major 1968), and in northwestern Montana it may extend from 3000 m down to 1700 m on ridges (Reid et al 2004). Stands occur on all aspects, although southerly exposures predominate in the northern extent and northerly exposures are common in the southern sites. Parent materials are variable and typically occur on residual and colluvial landforms of calcareous sedimentary rock (limestone predominates in Montana) (Cooper et al. 1997) and noncalcareous sedimentary lithologies (mostly argillite, siltstone and mudstone), as well as igneous and metamorphic rock (granite, gneiss) (Hess and Wasser 1982). Soils are poorly developed, well- to rapidly drained and skeletal (Regosols, Inceptisols). Soil surface is often gravelly because of the windswept, exposed nature of these sites. Disturbance from solifluction, slumps, and earthflows is common. Frost boiling and needle ice formation are common disturbances.
Geographic Range: Vegetation within this alliance has been reported from alpine habitats throughout the Rocky Mountain cordillera and alpine areas of high plateaus and ranges in the Colorado Plateau and Great Basin.

Nations: CA,US

States/Provinces:  AB, BC?, CO, ID?, MT, WA, WY


Confidence Level: Moderate

Confidence Level Comments: No Data Available
Grank: GNR

Greasons: No Data Available
Type Name Database Code Classification Code
Class 4 Polar & High Montane Scrub, Grassland & Barrens Class C04 4
Subclass 4.B Temperate to Polar Alpine & Tundra Vegetation Subclass S12 4.B
Formation 4.B.1 Temperate & Boreal Alpine Tundra Formation F037 4.B.1
Division 4.B.1.Nb Western North American Alpine Tundra Division D043 4.B.1.Nb
Macrogroup 4.B.1.Nb.2 Eight-petal Mountain-avens - Blackroot Sedge - Moss Campion Alpine Tundra Macrogroup M099 4.B.1.Nb.2
Group 4.B.1.Nb.2.a Eight-petal Mountain-avens - Mountain-heath species - Arctic Willow Alpine Dwarf-shrubland & Krummholz Group G316 4.B.1.Nb.2.a
Alliance A3178 Entireleaf Mountain-avens - Eight-petal Mountain-avens - Kinnikinnick Rocky Mountain Fell-field Dwarf-shrubland Alliance A3178 4.B.1.Nb.2.a
Association CEGL001890 Entireleaf Mountain-avens - Sedge species Alpine Dwarf-shrub Meadow CEGL001890 4.B.1.Nb.2.a
Association CEGL001891 Eight-petal Mountain-avens Alpine Dwarf-shrub Meadow CEGL001891 4.B.1.Nb.2.a
Association CEGL001892 Eight-petal Mountain-avens - Curly Sedge Alpine Dwarf-shrub Meadow CEGL001892 4.B.1.Nb.2.a
Association CEGL001893 Eight-petal Mountain-avens - Sedge species Alpine Dwarf-shrub Meadow CEGL001893 4.B.1.Nb.2.a
Association CEGL001894 Eight-petal Mountain-avens - Alpine Bistort Alpine Dwarf-shrub Meadow CEGL001894 4.B.1.Nb.2.a
Association CEGL005832 Kinnikinnick / Rocky Mountain Goldenrod Dwarf-shrubland CEGL005832 4.B.1.Nb.2.a
Concept Lineage: Much of the IV.A.8.N.c. Dryas octopetala Dwarf-shrub Herbaceous Alliance (A.1577) is included in this alliance and a single association from V.A.1.N.b. Arctostaphylos uva-ursi Dwarf-shrubland Alliance (A.1079) and V.A.8.N.c. Dryas integrifolia Dwarf-shrub Herbaceous Alliance (A.1576)

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: No Data Available
Concept Author(s): K.A. Schulz, in Faber-Langendoen et al. (2013)

Author of Description: K.A. Schulz

Acknowledgements: We have incorporated significant descriptive information previously compiled by D. Sarr, M. Damm, and M.S. Reid.

Version Date: 03-14-14
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