Print Report

CEGL001892 Dryas octopetala - Carex rupestris Alpine Dwarf-shrub Meadow

Type Concept Sentence: No Data Available

Common (Translated Scientific) Name: Eight-petal Mountain-avens - Curly Sedge Alpine Dwarf-shrub Meadow

Colloquial Name: No Data Available

Hierarchy Level:  Association

Type Concept: This alpine fell-field association is found throughout Colorado''s Rocky Mountains and in western and central Montana north into Alberta. This vegetation type represents the drier, mostly subxeric to submesic occurrences of Dryas octopetala-dominated dwarf-shrublands. It occurs predominantly in alpine environments (well above treeline); actual elevations vary from 3370 to 3900 m in the Colorado alpine to between 1700 and 2400 m in northwestern Montana. Typical terrain is moderately to steeply sloping, and all aspects are represented. The determining environmental parameter appears to be wind-scouring with sites blown snow-free in winter. Soils are very poorly developed and well- to rapidly drained. The association occurs on a wide variety of parent materials, though typically on residual and colluvial landforms. Where not protected by a dwarf-shrub mat, ground surfaces are composed of 5 to 60% exposed gravel, cobble and, to a much lesser degree, soil; litter can only accumulate immediately under the protection of the dwarf-shrub cover.

A mat of the dwarf-shrub Dryas octopetala dominates the visual aspect, with variable cover ranging from 10 to 80%. Usually mats occur in relatively evenly spaced windrows oriented perpendicular to the prevailing wind or along the edges of stepped terracettes. Other dwarf-shrubs include Salix arctica, Dasiphora fruticosa ssp. floribunda, Arctostaphylos uva-ursi, Juniperus communis, and Salix reticulata. Of the herbaceous component, graminoids generally have greater cover than forbs, a condition which is presumed to indicate the relatively xeric nature of the type. Carex rupestris has high constancy and occasionally is the dominant graminoid, but in Glacier National Park stands, there is no one dominant graminoid, only a variable suite of xeric-adapted species, including Carex nardina, Calamagrostis purpurascens, Calamagrostis koelerioides, Festuca brachyphylla, Poa alpina, and Trisetum spicatum. Typically the forb component does not exceed 10% cover, and that of individual forbs does not exceed 5%; those with highest constancy include Minuartia obtusiloba, Myosotis asiatica, Geum rossii, Artemisia scopulorum, Saxifraga bronchialis, Silene acaulis, Oxytropis campestris, Rhodiola rosea, Solidago multiradiata, Potentilla diversifolia, and Smelowskia calycina. Cover of mosses and lichens is very low.

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: Dryas octopetala-dominated communities and fellfields have been described from a number of studies in both Canada and the U.S. A systematic crosswalk of these types is needed to more clearly define what associations occur in the Canadian and U.S. Rocky Mountains. See Achuff et al. (2002a) for a review of some of the Canadian literature reporting Dryas communities.

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: No Data Available

Floristics: A mat of the dwarf-shrub Dryas octopetala dominates the visual aspect, with variable cover ranging from 10 to 80%. Usually mats occur in relatively evenly spaced windrows oriented perpendicular to the prevailing wind or along the edges of stepped terracettes. Other dwarf-shrubs include Salix arctica, Dasiphora fruticosa ssp. floribunda (= Pentaphylloides floribunda), Arctostaphylos uva-ursi, Juniperus communis, and Salix reticulata; any of these can occasionally have as much as 10% cover. Of the herbaceous component, graminoids generally have greater cover than forbs, a condition which is presumed to indicate the relatively xeric nature of the type. Carex rupestris has high constancy and is often the dominant graminoid, but in many stands there is no one dominant graminoid, only a variable suite of xeric-adapted species, including Carex nardina, Calamagrostis purpurascens, Calamagrostis koelerioides, Festuca brachyphylla, Poa alpina, and Trisetum spicatum. Typically the forb component does not exceed 15% cover, and that of individual forbs does not exceed 5%; those with highest constancy include Minuartia obtusiloba (= Arenaria obtusiloba), Myosotis asiatica, Geum rossii, Artemisia scopulorum, Saxifraga bronchialis, Silene acaulis, Oxytropis campestris, Rhodiola rosea (= Sedum roseum), Solidago multiradiata, Potentilla diversifolia, and Smelowskia calycina. Cover of mosses and lichens is very low.

Dynamics:  No Data Available
Environmental Description:  This alpine fell-field vegetation type represents the drier, mostly subxeric to submesic occurrences of Dryas octopetala-dominated dwarf-shrublands. It occurs predominantly in alpine environments (well above treeline); actual elevations vary from 3370 to 3900 m in the Colorado alpine to between 1700 and 2400 m in northwestern Montana. Typical terrain is moderately to steeply sloping, and all aspects are represented, though southerly exposures predominate in Montana, while northerly exposures are common in northern Colorado. Regardless of aspect, the determining environmental parameter appears to be wind-scouring with sites blown snow-free in winter. Soils are very poorly developed and well- to rapidly drained (Regosols, Inceptisols). The association occurs on a wide variety of parent materials, though typically on residual and colluvial landforms. Parent materials include calcareous sedimentary rock (limestone predominate in Montana) (Cooper et al. 1997) and noncalcareous sedimentary lithologies (mostly argillite and mudstone), as well as igneous and metamorphic rock (granite, gneiss) (Hess and Wasser 1982). Where not protected by a dwarf-shrub mat, ground surfaces are composed of 5 to 60% exposed gravel, cobble and, to a much lesser degree, soil; litter can only accumulate immediately under the protection of the dwarf-shrub cover.
Geographic Range: This alpine fell-field association is found throughout Colorado''s Rocky Mountains, and in western and central Montana north into Alberta. It is likely to occur elsewhere in the alpine of western North America.

Nations: CA,US

States/Provinces:  AB, CO, ID?, MT


Confidence Level: High

Confidence Level Comments: No Data Available
Grank: G4

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 CEGL001892 Eight-petal Mountain-avens - Curly Sedge Alpine Dwarf-shrub Meadow CEGL001892 4.B.1.Nb.2.a
Concept Lineage: No Data Available

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: = Dryas octopetala - Carex rupestris ssp. drummondiana Habitat Type/Association (Komarkova 1986)
= Dryas octopetala / Arenaria obtusiloba Habitat Type (Hess 1981) [Carex rupestris has 100% constancy and is the dominant graminoid with mean of 5% cover.]
= Dryas octopetala / Carex rupestris Habitat Type (Wasser and Hess 1982)
= Dryas octopetala / Carex rupestris Habitat Type (Hess and Wasser 1982)
= Dryas octopetala / Carex rupestris Herbaceous Vegetation (Cooper et al. 1999)
= Dryas octopetala / Carex rupestris Plant Association (Johnston 1987)
= Dryas octopetala/Carex rupestris c.t. (Cooper et al. 1997)
= Dryas octopetala (Welden 1981)
< Dryas Shrub Mat Community (Eddleman 1967)
= Dryasetum octopetalae Association (Kiener 1939) (Willard 1963)
= Dryasetum octopetalae Association (Kiener 1939) (Willard 1979)
= Dryasetum octopetalae, the northslope Association (Kiener 1967)
>< Salici nivalis - Dryadetum octopetalae Association (Damm 2001)
= Association Eritricho aretioidis - Dryasetum octopetalae (Kiener 1939 corr. Komarkova 1976) (Komarkova 1979)
>< H01: Dryas octopetala Vegetation Type (Achuff et al. 2002)
< Station #5 (Holway 1962a) [Dryas octopetala, Arenaria fendleri, Minuartia obtusiloba are dominant species.]
Concept Author(s): S.V. Cooper et al. (1997)

Author of Description: S.V. Cooper, M.S. Reid and K.A. Schulz

Acknowledgements: No Data Available

Version Date: 01-06-05
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