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A4021 Rocky Mountain Alpine Sparse Herb Bedrock & Scree Alliance

Type Concept Sentence: Vegetation with between 5-15% cover is predominantly vascular plant species of forbs and/or graminoids. Moss and other bryophytes may be present to abundant. It occurs in rocky alpine areas in the Rocky Mountain cordillera and alpine areas in high plateaus and ranges in the Colorado Plateau and Great Basin.

Common (Translated Scientific) Name: Rocky Mountain Alpine Sparse Herb Bedrock & Scree Alliance

Colloquial Name: Rocky Mountain Alpine Sparse Herb Bedrock & Scree

Hierarchy Level:  Alliance

Type Concept: Vegetation is predominantly vascular plant species of forbs and/or graminoids. Moss and other bryophytes may be present to as abundant as the vascular cover. Sparse cover of forbs, grasses, low shrubs and small trees may be present with total vascular plant cover typically between 5 and 15% due to the high cover of exposed rock. Many species are tiny, growing in cracks in rock outcrops. Some characteristic species include Astragalus kentrophyta, Astragalus molybdenus, Collomia larsenii, Dryas octopetala, Noccaea fendleri ssp. glauca, Townsendia leptotes, Townsendia rothrockii, and alpine species of Eriogonum and Phlox, as well as Achnatherum swallenii, Athyrium americanum, Carex perglobosa, Cirsium scopulorum, Cryptogramma acrostichoides, Ericameria discoidea, Hulsea algida, Ivesia cryptocaulis, Oxyria digyna, Phacelia hastata var. compacta, Polemonium viscosum, Saxifraga bronchialis, Saxifraga chrysantha, Saxifraga mertensiana, Saxifraga rivularis, Senecio taraxacoides, Silene acaulis, and Sphaeromeria argentea. This alpine alliance is found throughout the Rocky Mountain cordillera and alpine areas in high plateaus and ranges in the Colorado Plateau and Great Basin. Stands occur in rock outcrop, cliff crevices, unstable talus and scree slopes, and boulder fields. Elevation ranges from 3000-3915 m in Colorado to 1600-2400 m in northwestern Montana. Sites occur on all aspects near the upper elevational limit for vascular plants; only nonvascular mosses, lichens, and algae survive at higher altitudes. Soils are young and poorly developed due to low soil temperature, low soil moisture during the summer, and a short growing season.

Diagnostic Characteristics: Sparsely vegetated rock outcrop, scree and other rocky areas that have at least 5% but not more than 15% of vascular plant cover. Bryophytic cover may be higher than the vascular cover. Areas with high bryophytic cover and low (<5%) vascular cover fall into the alpine bryophyte alliance. This alpine alliance is predominantly vascular plant species, forbs and/or graminoids with high species diversity overall, although it may be low on a given site. Sparse cover of forbs, grasses, low shrubs and small trees may be present with total vascular plant cover typically 5-15% due to the high cover of exposed rock. Diagnostic species include Achnatherum swallenii, Astragalus kentrophyta, Astragalus molybdenus, Athyrium americanum, Carex perglobosa, Cirsium scopulorum, Collomia larsenii, Cryptogramma acrostichoides, Dryas octopetala, Ericameria discoidea, Hulsea algida, Ivesia cryptocaulis, Oxyria digyna, Penstemon rydbergii, Phacelia hastata var. compacta, Polemonium viscosum, Potentilla glandulosa, Saxifraga bronchialis, Saxifraga chrysantha, Saxifraga mertensiana, Saxifraga rivularis, Senecio taraxacoides, Silene acaulis, Sphaeromeria argentea, Noccaea fendleri ssp. glauca, Townsendia leptotes, and Townsendia rothrockii.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: Sparsely vegetated rock-dominated areas of the alpine are not well-studied, so the description does not cover the full range of biodiversity and characteristics of these communities. ~Sphaeromeria argentea - Achnatherum swallenii Alpine Sparse Meadow (CEGL001993)$$ occurs on alluvial fans at elevations from approximately 1890 to 1980 m that are similar to windswept tundra vegetation (Caicco and Wellner 1983l) and needs further review to verify this is the appropriate alliance and group.

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: This alliance is characterized by a rock-dominated substrate and a moderate cover of perennial forbs and graminoids. Moss cover ranges from very sparse to greater cover than the vascular plants depending on soil moisture of the site.

Floristics: This alpine alliance is predominantly vascular plant species of forbs and/or graminoids. Vascular species diversity is high overall, although it may be low on a given site. Sparse cover of forbs, grasses, low shrubs and small trees may be present with total vascular plant cover typically between 5 and 15% due to the high cover of exposed rock. Many species are tiny, growing in cracks in rock outcrops. Some characteristic species include Astragalus kentrophyta, Astragalus molybdenus (= Astragalus plumbeus), Collomia larsenii, Dryas octopetala, Noccaea fendleri ssp. glauca (= Thlaspi alpestre), Townsendia leptotes, Townsendia rothrockii, and alpine species of Eriogonum and Phlox, as well as Achnatherum swallenii, Athyrium americanum, Carex perglobosa, Cirsium scopulorum, Cryptogramma acrostichoides, Ericameria discoidea, Hulsea algida, Ivesia cryptocaulis, Oxyria digyna, Penstemon rydbergii, Phacelia hastata var. compacta, Polemonium viscosum, Potentilla glandulosa, Saxifraga bronchialis, Saxifraga chrysantha, Saxifraga mertensiana, Saxifraga rivularis, Senecio taraxacoides, Silene acaulis, and Sphaeromeria argentea. Other associated species include Achillea millefolium, Besseya alpina, Campanula rotundifolia, Festuca brachyphylla, Geum rossii, Heuchera parvifolia var. nivalis, Ionactis alpina, Luzula spicata, Minuartia nuttallii, Phacelia sericea, Poa lettermanii, Ranunculus pygmaeus, Saxifraga caespitosa ssp. delicatula, Senecio fremontii, Silene acaulis, Trifolium dasyphyllum, and Trisetum spicatum. The nonvascular layer may be sparse or have a greater cover than the vascular species depending on soil moisture and other site variables. Hypnum revolutum and Pohlia sp. are constant bryophyte species. Other wet-site bryophytes may include Philonotis fontana var. americana, Brachythecium spp., and Bryum spp. Lichens are mostly found on rock surfaces, amounts ranging from nil to 50%.

Dynamics:  There is often evidence of marmot and pika in stands of this alliance.
Environmental Description:  This alpine alliance is found throughout the Rocky Mountain cordillera and alpine areas in high plateaus and ranges in the Colorado Plateau and Great Basin. The climate regime is continental, with long, cold winters and short summers with frequent afternoon thunderstorms. Strong westerly winds are common in the winter. Stands are located in the subnival zone, the area just below permanent snow and ice, on rock faces and summits of high peaks and extend down into the upper subalpine. Elevation ranges from 3000-3915 m in Colorado (Komarkova 1976). Stands in northwestern Montana were sampled between 1600-2400 m. Stands occur on rock outcrops, talus and scree slopes, boulderfields and moist crevices occurring in subalpine to more often alpine cliff faces and overhangs. Sites occur on all aspects near the upper elevational limit for vascular plants; only nonvascular mosses, lichens, and algae survive at higher altitudes. Soils are young and poorly developed due to low soil temperature, low soil moisture during the summer, and a short growing season. Soils are classified as Entisols (Cryorthents) (Kiener 1967, Komarkova 1976). The soil profile has only one thin horizon. Soils tend to be coarse-textured, rapidly drained gravelly or sandy loam, loamy sand, and sandy clay. Stands are dominated by rock cover (15-95%) and gravel (0-60%).
Geographic Range: This alpine alliance is found throughout the Rocky Mountain cordillera and alpine areas in high plateaus and ranges in the Colorado Plateau and Great Basin from New Mexico to central Alberta and British Columbia and Intermountain West ranges.

Nations: CA,US

States/Provinces:  AB, CO, ID, MT, NV, WY


Confidence Level: Low

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.c Eight-petal Mountain-avens - Saxifrage species Rocky Mountain Alpine Bedrock & Scree Group G571 4.B.1.Nb.2.c
Alliance A4021 Rocky Mountain Alpine Sparse Herb Bedrock & Scree Alliance A4021 4.B.1.Nb.2.c
Association CEGL001849 Alpine Ladyfern Alpine Sparse Vegetation CEGL001849 4.B.1.Nb.2.c
Association CEGL001858 Globe Sedge - Moss Campion Alpine Sparse Meadow CEGL001858 4.B.1.Nb.2.c
Association CEGL001929 Gold-bloom Saxifrage Alpine Sparse Vegetation CEGL001929 4.B.1.Nb.2.c
Association CEGL001930 Weak Saxifrage Alpine Sparse Meadow CEGL001930 4.B.1.Nb.2.c
Association CEGL001932 Dandelion Ragwort - Alpine Mountain-sorrel Alpine Sparse Meadow CEGL001932 4.B.1.Nb.2.c
Association CEGL001959 Mountain Thistle - Sticky Jacob''s-ladder Alpine Sparse Meadow CEGL001959 4.B.1.Nb.2.c
Association CEGL001993 Silver Chicken-sage - Swallen''s Needlegrass Alpine Sparse Meadow CEGL001993 4.B.1.Nb.2.c
Association CEGL002735 Charleston Peak Mousetail Alpine Sparse Vegetation CEGL002735 4.B.1.Nb.2.c
Association CEGL005900 Alpine Ladyfern - American Rockbrake Alpine Sparse Vegetation CEGL005900 4.B.1.Nb.2.c
Association CEGL005902 Yellow-spot Saxifrage Scree Slope Alpine Sparse Vegetation CEGL005902 4.B.1.Nb.2.c
Association CEGL005903 Wood Saxifrage Cliff Alpine Crevice CEGL005903 4.B.1.Nb.2.c
Concept Lineage: No Data Available

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: > Saxifragetum chrysanthae Association (Komarkova 1976)
> Saxifragetum chrysanthae Association (Kiener 1967)
> Crevice Habitats (Younkin 1970)
Concept Author(s): M.S. Reid and K.A. Schulz, in Faber-Langendoen et al. (2013)

Author of Description: M.S. Reid

Acknowledgements: We have incorporated significant descriptive information previously compiled by M. Damm.

Version Date: 03-14-14
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