Invalid Unit Specified
M099 Dryas octopetala - Carex elynoides - Silene acaulis Alpine Tundra Macrogroup

The U.S. National
Vegetation Classification
Type Concept Sentence: This alpine macrogroup includes sparse cushion plants to dense turf or dwarf-shrublands. It occurs at and above upper timberline in relatively dry conditions throughout the central and southern Rocky Mountains cordillera from New Mexico north into Canada and includes alpine areas in the Utah high plateaus and high ranges in the Great Basin west into the Sierra Nevada and southern and eastern Cascades and southern interior mountain ranges of British Columbia.
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Common (Translated Scientific) Name: Eight-petal Mountain-avens - Blackroot Sedge - Moss Campion Alpine Tundra Macrogroup
Colloquial Name: Rocky Mountain-Sierran Alpine Tundra
Hierarchy Level: Macrogroup
Type Concept: This macrogroup occurs at and above upper timberline throughout the Rocky Mountains cordillera from New Mexico and the Sierra Nevada north into southwestern Alberta and southeastern and south-central British Columbia. Vegetation physiognomy ranges from sparse cushion plants to dense turf or dwarf-shrublands. Most fell-field plants are cushioned or matted, frequently succulent, flat to the ground in rosettes, and often densely haired and thickly cutinized. Plant cover is 15-50%, while exposed rocks with crustose lichens make up the rest. Fell-fields are usually found within or adjacent to alpine dry turf. Common species include Arenaria capillaris, Geum rossii, Kobresia myosuroides, Minuartia obtusiloba, Myosotis asiatica, Paronychia pulvinata, Phlox pulvinata, Silene acaulis, Trifolium dasyphyllum, and Trifolium parryi. The moderately dense to dense cover of low-growing, perennial graminoids and forbs include Artemisia arctica, Carex elynoides, Carex siccata, Carex scirpoidea, Carex nardina, Carex rupestris, Festuca brachyphylla, Festuca idahoensis, Geum rossii, Juncus drummondii, Kobresia myosuroides, Phlox pulvinata, and Trifolium dasyphyllum. Dwarf-shrublands are characterized by a semi-continuous layer of ericaceous dwarf-shrubs or dwarf willows less than 0.5 m in height. Dense tufts of graminoids and scattered forbs occur. Dryas octopetala- and Dryas integrifolia-dominated communities occur on more windswept and drier sites than the heath communities. Within the heath-willow communities Cassiope mertensiana, Salix arctica, Salix reticulata, Salix vestita, or Phyllodoce empetriformis can be dominant shrubs. Ledum glandulosum, Kalmia microphylla, Phyllodoce glanduliflora, and Vaccinium spp. may also be shrub associates. Snowbed communities are characterized by Sibbaldia procumbens and Carex subnigricans. Species composition overlaps across the range of this macrogroup, although there is some significant regional and local variation. The drier alpine vegetation of the Great Basin ranges and Sierra Nevada may include lower elevation semi-desert species such as Carex filifolia, Poa fendleriana, Poa secunda, and Artemisia frigida. Environments are varied due to climatic and site variation. Wind and its effect on snow movement has a strong local effect, producing wind-scoured fell-fields, dry turf, snow accumulation heath communities, and short growing season snowbed sites. Fell-fields are typically free of snow during the winter as they are found on ridgetops, upper slopes and exposed saddles, whereas dry turf is found on gentle to moderate slopes, flat ridges, valleys, and basins where the soil has become relatively stabilized and the water supply is more-or-less constant. Dwarf-shrubland sites tend to be in level or concave areas with late-lying snow and subirrigation from surrounding slopes.
Diagnostic Characteristics: This macrogroup includes open to closed-(shrub) canopy, herbaceous stands dominated by alpine graminoids and forbs (especially cushion plants), as well as open to closed, often evergreen (ericaceous) dwarf-shrubland stands. The vegetation occurs as a mosaic of small-patch plant communities. Stands include alpine turf and fell-fields dominated or codominated by Antennaria spp., Calamagrostis breweri, Carex elynoides, Carex helleri, Carex filifolia, Carex rupestris, and Kobresia myosuroides and forbs such as Geum rossii, especially cushion plants Trifolium dasyphyllum and Phlox pulvinata (fell-fields). Dwarf-shrublands are characterized by Dryas octopetala and Dryas integrifolia, Ericameria discoidea, on drier sites, and Cassiope mertensiana, Salix arctica, Salix reticulata, Salix vestita, or Phyllodoce empetriformis with Ledum glandulosum, Kalmia microphylla, Phyllodoce glanduliflora, and Vaccinium spp. present to codominant on more typical mesic heath communities in the northern portion of the Central Rockies.
Rationale for Nominal Species or Physiognomic Features: The wide-ranging dwarf-shrub Dryas octopetala is the lead species. Silene acaulis is a widespread fell-field plant and Carex elynoides is a common dry turf species, although it does not occur in the most northern stands.
Classification Comments: Alpine turf, fell-field and dwarf-shrubland are included together for several reasons. Although these types can be quite different and can have relatively abrupt boundaries in saddles, there is often a long transition on broad alpine slopes. Species composition is similar across the distribution of this macrogroup, although there is some significant regional and local variation. The generally drier and patchier alpine vegetation of the Great Basin ranges and Sierra Nevada may include lower elevation semi-desert species such as Carex filifolia, Poa fendleriana, Poa secunda, and Artemisia frigida. The dwarf-shrublands are more distinct in the mesic northern extent than in the southern and drier ranges in the Great Basin and Colorado Plateau. In the northern extent, the dwarf-shrub layers tend to be denser and characterized by distinctive alpine heath species Cassiope mertensiana, Phyllodoce empetriformis, Salix glauca, and Salix reticulata. In the southern extent, stands dominated by Salix arctica, Salix reticulata, or Salix nivalis are less distinctive and occur as patches within the alpine turf or mesic bands around snowbeds (Cooper et al. 1997). Dryas octopetala and Dryas integrifolia often occur on harsh windblown sites on dry turf, cushion plant fell-fields or unstable scree slopes, whereas the heath types of Cassiope mertensiana, Salix reticulata, or Phyllodoce empetriformis occur as snowbed or wetland communities (Cooper et al. 1997). Some of the dwarf Salix species, such as Salix arctica, form mesic patches within the larger alpine turf communities (Lewis 1970, Zwinger and Willard 1996, Cooper et al. 1997).

This macrogroup includes Mount Lassen and Mount Shasta and the eastern portion of the southern Cascades because of the relatively dry climate that does not typically form an "alpine heath" typical of stands in Vancouverian Alpine Tundra Macrogroup (M101), except as part of snowbed or wetland communities.
Similar NVC Types:
M404 Western Boreal Alpine Tundra, note: is relatively mesic alpine in comparison with different diagnostic species.
M101 Vancouverian Alpine Tundra, note: is relatively mesic alpine in comparison with different diagnostic species.
Physiognomy and Structure: This macrogroup is variable structurally and includes graminoid- and forb (cushion plant)-dominated, open to closed-canopy, herbaceous stands as well as stands with dwarf-shrublands. Although some turf communities are extensive, the vegetation overall is a mosaic of small-patch plant communities.
Floristics: This widespread distributed macrogroup has variable vegetation structure and composition, ranging from sparsely vegetated fell-fields to dense turf or dwarf-shrublands. Most fell-field plants are cushioned or matted, frequently succulent, flat to the ground in rosettes, and often densely haired and thickly cutinized. Plant cover on fell-fields is 15-50%, while exposed rocks covered with crustose lichens make up the rest. They are usually found on wind-exposed ridges and saddles, within or adjacent to alpine dry turf. Common species include Arenaria capillaris, Geum rossii, Kobresia myosuroides, Minuartia obtusiloba, Myosotis asiatica, Paronychia pulvinata, Phlox pulvinata, Potentilla nivea, Potentilla villosa, Potentilla diversifolia, Saxifraga bronchialis, Silene acaulis, Trifolium dasyphyllum, and Trifolium parryi. The low-growing, perennial vegetation ranges from sparse to moderate cover dominated by cushion plants to moderately dense to dense cover of low-growing, perennial graminoids and forbs forming a turf. Rhizomatous, sod-forming sedges are the dominant graminoids, and prostrate and mat-forming plants with thick rootstocks or taproots characterize the forbs. Dominant species include Artemisia arctica, Carex elynoides, Carex siccata, Carex scirpoidea, Carex nardina, Carex rupestris, Festuca brachyphylla, Festuca idahoensis, Geum rossii, Juncus drummondii, Kobresia myosuroides, Phlox pulvinata, and Trifolium dasyphyllum. Dwarf-shrubland stands are characterized by a semi-continuous layer of ericaceous dwarf-shrubs or dwarf willows which form a heath type ground cover less than 0.5 m in height. Dense tuffs of graminoids and scattered forbs occur. Dryas octopetala- and Dryas integrifolia-dominated communities occur on more windswept and drier sites than the heath communities. Dwarf willows are often found with Dryas, including Salix nivalis or Salix reticulata. Within the heath communities Cassiope mertensiana (dominates in snowier climates), Salix arctica, Salix vestita, Phyllodoce empetriformis, or Phyllodoce glanduliflora can be dominant shrubs. Ledum glandulosum, Kalmia microphylla, Phyllodoce glanduliflora, and Vaccinium spp. may also be shrub associates. Snowbed communities are also included in this macrogroup and are characterized by indicator species Carex subnigricans and Sibbaldia procumbens with Juncus drummondii and Luzula piperi common on eroding sites.

Species composition overlaps across the range of this macrogroup, although there is some significant regional and local variation. In Great Basin and Sierra Nevada stands, common species include Aquilegia pubescens, Castilleja nana, Draba densifolia, Eriogonum incanum, Linanthus pungens (= Leptodactylon pungens), Minuartia nuttallii (= Arenaria nuttallii), Oxyria digyna, Phlox covillei, and Phlox pulvinata. Characteristic graminoid species include Carex congdonii, Calamagrostis breweri, Calamagrostis purpurascens, Carex exserta, Juncus parryi, and Trisetum spicatum. Common forbs include many of the fell-field species and Antennaria media, Arenaria kingii, Erigeron compositus, Erigeron pygmaeus, Eriogonum gracilipes, Eriogonum ovalifolium, Eriogonum roseum, Penstemon heterodoxus, Phlox covillei, Podistera nevadensis, Carlquistia muirii (= Raillardella muirii), and others. Alpine dwarf-shrublands are dominated or codominated by Cassiope mertensiana, Ericameria discoidea, Kalmia microphylla, Polygonum shastense, Phyllodoce breweri, Ribes cereum, Salix arctica, and Vaccinium cespitosum.

The drier alpine vegetation of the Great Basin ranges and Sierra Nevada may include lower elevation semi-desert species such as Carex filifolia, Poa fendleriana, Poa secunda and Artemisia frigida. In the northern range, meadows can be extensive at lower elevations. Key species of these meadows are Arnica latifolia, Erigeron peregrinus, Lupinus arcticus, Senecio triangularis, Valeriana sitchensis, and Veratrum viride; other species include Carex spectabilis, Claytonia lanceolata, Erythronium grandiflorum, Pulsatilla occidentalis (= Anemone occidentalis), and Trollius laxus ssp. albiflorus. Floristic information was compiled from Baker (1980a), Bamberg (1961), Bamberg and Major (1968), Billings (2000), Cooper et al. (1997), Holland and Keil (1995), Komarkova (1976, 1980), Lewis (1970), Sawyer and Keeler-Wolf (1995, 2007), Sawyer et al. (2009), Willard (1963), and Zwinger and Willard (1996).
Dynamics: Vegetation in these areas is controlled by snow retention, wind desiccation, soil moisture and a short growing season. Disturbances tend to be small-scale and localized, such as by burrowing pocket gophers. Permafrost may only occur in localized areas, such as in the Canadian Rockies.
Environmental Description: This widespread alpine macrogroup occurs at and above the upper treeline throughout the Rocky Mountains cordillera and alpine areas of mountain ranges in Utah and Nevada, and in isolated alpine sites in the northeastern Cascades south to the Sierra Nevada. Elevations are above 3360 m in the Colorado Rockies but drop to less than 2100 m in northwestern Montana and in the mountains of into southwestern Alberta and southeastern British Columbia. Sierran Nevada stands begin around 3500 m elevation in the southern mountains and begin at approximately 2700 m in the Klamath Mountains and southern Cascade Range. This macrogroup includes wind-scoured fell-fields and dry turf and dwarf-shrublands. Fell-fields are typically free of snow during the winter as they are found on ridgetops, upper slopes and exposed saddles, whereas dry turf is found on gentle to moderate slopes, flat ridges, valleys, and basins where the soil has become relatively stabilized and the water supply is more-or-less constant. Dwarf-shrubland sites tend to be level or concave areas of glacial topography, with late-lying snow and subirrigation from surrounding slopes. Vegetation in these areas is controlled by snow retention, wind desiccation, permafrost, and a short growing season.

Climate is continental temperate, and due to the high elevations, long cold snowy winters and a very short growing season result. It is typically drier than either the Vancouverian or Boreal alpine vegetation. The precipitation regime is strongly seasonal, with most precipitation falling in the winter months as snow. Summers are mostly dry. Substrates are variable across fell-fields, alpine turf and dwarf-shrub vegetation. Fell-field sites are generally shallow, stony, low in organic matter, and poorly developed with wind deflation often resulting in a gravelly pavement. Alpine turf sites have deeper, more developed soils, although there may have moderately high cover of cobbles and boulders present. The dwarf-shrubland soils have become relatively stabilized, are moist but well-drained, strongly acidic, and often have substantial peat layers. Environmental information was compiled from Baker (1980a), Bamberg (1961), Bamberg and Major (1968), Billings 2000, Cooper et al. (1997), Holland and Keil (1995), Komarkova (1976, 1980), Lewis (1970), Sawyer and Keeler-Wolf (1995, 2007), Sawyer et al. (2009), Willard (1963), and Zwinger and Willard (1996).
Geographic Range: This macrogroup occurs above upper timberline throughout the Rocky Mountains cordillera from New Mexico north into southwestern Alberta and south-central and southeastern British Columbia, Canada, and includes alpine areas west in the Utah high plateaus and high ranges in the Great Basin and Sierra Nevada. Stands of this macrogroup also extend north into the Klamath Mountains and drier southern and eastern Cascade Range, and south as far south as the Peninsular Ranges and White Mountains.
Nations: CA, US
States/Provinces: AB, AZ, BC, CA, CO, ID, MT, NM, NV, OR, UT, WA, WY
US Forest Service Ecoregions (2007)
Domain Name:
Division Name:
Province Name: Southern Rocky Mountain Steppe - Open Woodland - Coniferous Forest - Alpine Meadow Province
Province Code: M331    Occurrence Status: Confident or certain
Section Name: Yellowstone Highlands Section
Section Code: M331A     Occurrence Status: Confident or certain
Omernik Ecoregions:
Plot Analysis Summary:
Confidence Level: Moderate
Confidence Level Comments:
Grank: GNR
Greasons:
Concept Lineage: This macrogroup is composed of ~Rocky Mountain Alpine Turf & Fell-Field (G314)$$, ~Rocky Mountain Alpine Dwarf-Shrubland G316)$$, and ~Sierran Alpine Tundra & Fell-Field (G363)$$ which was moved from ~Vancouverian Alpine Scrub, Forb Meadow & Grassland (M101)$$to M099.
Predecessors:
Obsolete Names:
Obsolete Parents:
Synonomy: < AT Alpine Tundra (mesic to dry sites) (Ecosystems Working Group 1998)
< Alpine Grassland (213) (Shiflet 1994) [SRM type 213 includes all alpine communities in Sierra, Klamath and California Cascades, both herbaceous and shrub dominated, and wet meadows.]
< Alpine Rangeland (410) (Shiflet 1994)
Concept Author(s): K.A. Schulz, in Faber-Langendoen et al. (2014)
Author of Description: K.A. Schulz
Acknowledgements:
Version Date: 15Oct2014
References:
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