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G571 Dryas octopetala - Saxifraga spp. Rocky Mountain Alpine Bedrock & Scree Group
Type Concept Sentence: This barren and sparsely vegetated alpine group consists of exposed rock and rubble at or above the upper treeline in the Rocky Mountains, from Alberta and British Columbia, Canada, south into New Mexico, and west into the highest mountain ranges of the Great Basin, eastern Oregon and Washington, and the Sierra Nevada.
Common (Translated Scientific) Name: Eight-petal Mountain-avens - Saxifrage species Rocky Mountain Alpine Bedrock & Scree Group
Colloquial Name: Rocky Mountain & Sierran Alpine Bedrock & Scree
Hierarchy Level: Group
Type Concept: This alpine group consists of exposed rock and rubble at or above the upper treeline in the Rocky Mountains, from Alberta and British Columbia, Canada, south into New Mexico, and west into the highest mountain ranges of the Great Basin, eastern Oregon and Washington, and the Sierra Nevada. It is composed of barren and sparsely vegetated alpine substrates, typically including bedrock outcrops, talus and scree slopes, upper mountain slopes, and summits. Vascular plants growing on loose substrates typically have either an extensive shallow root and rhizome system or a massive taproot that anchors the plant. Sparse cover of forbs, grasses, low shrubs and small trees may be present with total vascular plant cover typically less than 25% due to the high cover of exposed rock. Many species are tiny, growing in cracks in rock outcrops. Nonvascular (lichen)-dominated communities are common and may greatly exceed 25% cover in some areas. The lower elevational limit for the alpine zone varies with latitude ranging from near 3660 m (12,000 feet) in the southern extent to near 2286 m (7500 feet) in the northern extent. Exposure to desiccating winds, rocky and sometimes unstable substrates, and a short growing season limit vascular plant growth.
Diagnostic Characteristics: No Data Available
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: This group is composed of sparse cover of alpine plants sometimes with abundant nonvascular (lichen) cover. Because it occurs on rock outcrops, it may occur as inclusions within the more extensive ~Rocky Mountain-Sierran Alpine Turf & Fell-Field Group (G314)$$.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: This group includes sparsely vegetated and nonvascular-dominated rocks growing above upper treeline.
Floristics: This group is composed of barren and sparsely vegetated alpine substrates. Exposure to desiccating winds, rocky and sometimes unstable substrates, and a short growing season limit vascular plant growth. Vascular plants growing on loose substrates typically have either an extensive shallow root and rhizome system or a massive taproot that anchors the plant. Sparse cover of forbs, grasses, low shrubs and small trees may be present with total vascular plant cover typically less than 25% due to the high cover of exposed rock. Many species are tiny, growing in cracks in rock outcrops. Some characteristic species include Dryas octopetala, Astragalus kentrophyta, Astragalus molybdenus (= Astragalus plumbeus), Collomia larsenii, Noccaea fendleri ssp. glauca (= Thlaspi alpestre), Townsendia leptotes, Townsendia rothrockii, Trisetum spicatum, and alpine species of Eriogonum and Phlox. 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. Characteristic species in the Sierra Nevada include Achnatherum swallenii, Athyrium americanum, Carex perglobosa, Castilleja nana, Cirsium scopulorum, Hulsea algida, Ivesia cryptocaulis, Oxyria digyna, Polemonium viscosum, Saxifraga bronchialis, Saxifraga chrysantha, Saxifraga mertensiana, Saxifraga rivularis, Selaginella watsonii, Senecio taraxacoides, Silene acaulis, and Sphaeromeria argentea. Ericameria discoidea, Juniperus communis, and Ribes montigenum are common shrub associates.
Nonvascular (lichen)-dominated communities are common and may greatly exceed 25% in cover in some areas. Lichens are diverse Common lichens on boulderfields are Buellia sp., Candelaria sp., Cladonia pyxidata, Lecidea atrobrunnea, Rhizocarpon geographicum, Rhizoplaca chrysoleuca (= Lecanora rubina), Umbilicaria proboscidea, Umbilicaria anthracina, Umbilicaria proboscidea, Xanthoparmelia conspersa (= Parmelia conspersa), Rusavskia elegans (= Caloplaca elegans), and on late-melting snowbeds sites Solorina crocea (Zwinger and Willard 1996). Common and abundant bryophytes may include Aulacomnium palustre, Bryum spp., Hypnum revolutum, Philonotis fontana, Pohlia sp., Polytrichastrum alpinum, Polytrichum piliferum, and Philonotis fontana var. pumila (= Philonotis tomentella). Floristic information was compiled from Willard (1963), Komarkova (1976, 1980), Zwinger and Willard (1996), and Cooper et al. (1997).
Nonvascular (lichen)-dominated communities are common and may greatly exceed 25% in cover in some areas. Lichens are diverse Common lichens on boulderfields are Buellia sp., Candelaria sp., Cladonia pyxidata, Lecidea atrobrunnea, Rhizocarpon geographicum, Rhizoplaca chrysoleuca (= Lecanora rubina), Umbilicaria proboscidea, Umbilicaria anthracina, Umbilicaria proboscidea, Xanthoparmelia conspersa (= Parmelia conspersa), Rusavskia elegans (= Caloplaca elegans), and on late-melting snowbeds sites Solorina crocea (Zwinger and Willard 1996). Common and abundant bryophytes may include Aulacomnium palustre, Bryum spp., Hypnum revolutum, Philonotis fontana, Pohlia sp., Polytrichastrum alpinum, Polytrichum piliferum, and Philonotis fontana var. pumila (= Philonotis tomentella). Floristic information was compiled from Willard (1963), Komarkova (1976, 1980), Zwinger and Willard (1996), and Cooper et al. (1997).
Dynamics: Stands in the more xeric alpine in the Great Basin and southern Sierra Nevada include lower elevation semi-desert species such as Poa secunda and Petrophyton caespitosum.
Environmental Description: This alpine group consists of exposed rock and rubble at or above the upper treeline in the Rocky Mountains, from Alberta and British Columbia, Canada, south into New Mexico, and west into the highest mountain ranges of the Great Basin and the Sierra Nevada. The lower elevational limit for the alpine zone varies with latitude ranging from near 3660 m (12,000 feet) in the southern extent to near 2286 m (7500 feet) in the northern extent. The alpine zone in the Sierra Nevada begins at 3200 m (10,500) in the south and lower to 2895 m (9500 feet) in the northern extent (Zwinger and Willard 1996). The alpine zone extends further downslope on cooler north aspects. Exposure to desiccating winds, rocky and sometimes unstable substrates, and a short growing season limit vascular plant growth.
Geographic Range: This group is restricted to the highest elevations of the Rocky Mountains, from Alberta and British Columbia, Canada, south into New Mexico, and west into the highest mountain ranges of the Great Basin, eastern Oregon and Washington, and the Sierra Nevada.
Nations: CA,US
States/Provinces: AB, AZ, BC, CA, CO, ID, MT, NM, NV, OR, UT, WA, WY
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.849164
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.c Eight-petal Mountain-avens - Saxifrage species Rocky Mountain Alpine Bedrock & Scree Group | G571 | 4.B.1.Nb.2.c |
| Alliance | A3786 Sierran Alpine Nonvascular Bedrock & Scree Alliance | A3786 | 4.B.1.Nb.2.c |
| Alliance | A4021 Rocky Mountain Alpine Sparse Herb Bedrock & Scree Alliance | A4021 | 4.B.1.Nb.2.c |
| Alliance | A4022 Rocky Mountain Alpine Nonvascular Bedrock & Scree Alliance | A4022 | 4.B.1.Nb.2.c |
| Alliance | A4088 Jacob''s-ladder species - Indian-paintbrush species - Oatgrass species Alpine Rock Alliance | A4088 | 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: >< Alpine Rangeland (410) (Shiflet 1994)
> Boulder Fields (Zwinger and Willard 1996)
> Talus and Scree Slopes (Zwinger and Willard 1996)
> Boulder Fields (Zwinger and Willard 1996)
> Talus and Scree Slopes (Zwinger and Willard 1996)
- Cooper, S. V., P. Lesica, and D. Page-Dumroese. 1997. Plant community classification for alpine vegetation on Beaverhead National Forest, Montana. Report INT-GTR-362. USDA Forest Service, Intermountain Research Station, Ogden, UT. 61 pp.
- Faber-Langendoen, D., J. Drake, S. Gawler, M. Hall, C. Josse, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, L. Sneddon, K. Schulz, J. Teague, M. Russo, K. Snow, and P. Comer, editors. 2010-2019a. Divisions, Macrogroups and Groups for the Revised U.S. National Vegetation Classification. NatureServe, Arlington, VA. plus appendices. [in preparation]
- Komarkova, V. 1976. Alpine vegetation of the Indian Peaks Area, Front Range, Colorado Rocky Mountains. Unpublished dissertation, University of Colorado, Boulder. 655 pp.
- Komarkova, V. 1980. Classification and ordination in the Indian Peaks area, Colorado Rocky Mountains. Vegetatio 42:149-163.
- Shiflet, T. N., editor. 1994. Rangeland cover types of the United States. Society for Range Management. Denver, CO. 152 pp.
- Willard, B. E. 1963. Phytosociology of the alpine tundra of Trail Ridge, Rocky Mountain National Park, Colorado. Unpublished dissertation, University of Colorado, Boulder.
- Zwinger, A. H., and B. E. Willard. 1996. Land above the trees: A guide to American alpine tundra. Johnson Books, Boulder, CO. 425 pp.