Print Report

A3172 Juncus drummondii - Juncus parryi - Sibbaldia procumbens Rocky Mountain Alpine Snowbed Alliance

Type Concept Sentence: This Rocky Mountain alpine alliance includes late-melting snowbed communities dominated by diagnostic species such as Carex ebenea, Carex nigricans, Carex paysonis, Carex pyrenaica, Carex subnigricans, Juncus drummondii, Juncus parryi, Poa arctica ssp. grayana, Trifolium parryi, and snowbed indicator species Sibbaldia procumbens with many other high-constancy species indicative of wet-mesic conditions during the growing season.

Common (Translated Scientific) Name: Drummond''s Rush - Parry''s Rush - Creeping Sibbaldia Rocky Mountain Alpine Snowbed Alliance

Colloquial Name: Rocky Mountain Rush - Sibbaldia Alpine Snowbed

Hierarchy Level:  Alliance

Type Concept: These snowbed communities are characterized by a low to dense herbaceous layer dominated by diagnostic species Carex ebenea, Carex nigricans, Carex paysonis, Carex pyrenaica, Carex subnigricans, Juncus drummondii, Juncus parryi, Poa arctica ssp. grayana, Trifolium parryi, and snowbed indicator species Sibbaldia procumbens. In the more xeric stands, a moss layer dominated by Polytrichastrum alpinum, Polytrichum piliferum, or Pohlia obtusifolia can be present. This small-patch alpine alliance occurs in the Rocky Mountain cordillera and high-elevation areas in the Colorado Plateau and Great Basin and is frequently found on the lee side of ridges and in depressions where late-melting snowbed and hygric swales are fed by snowmelt and seeps occur. Stands are located on lee sides of ridges, saddles, hills and knolls, and rock outcrops and in snow-filled depressions from 2520-3760 m elevation depending on latitude. The snowmelt creates wet-mesic soil conditions that last through most of the growing season and can produce lush vegetation. Snowbed communities often develop in concentric rings with later melting communities in the center. Some sites do not become snow-free until August and have a very short growing season with little time for vegetation to develop. Substrates are variable and range from muck to well-drained, shallow, coarse to fine-textured mineral soil.

Diagnostic Characteristics: This Rocky Mountain alpine alliance includes late-melting snowbed herbaceous communities dominated by diagnostic species Carex ebenea, Carex nigricans, Carex paysonis, Carex pyrenaica, Carex subnigricans, Juncus drummondii, Juncus parryi, Poa arctica ssp. grayana, Trifolium parryi, and snowbed indicator species Sibbaldia procumbens. Other high-constancy diagnostic species include Antennaria alpina, Antennaria lanata, Antennaria media, Arenaria capillaris, Artemisia arctica ssp. arctica, Caltha leptosepala, Carex phaeocephala, Castilleja occidentalis, Erigeron melanocephalus, Erigeron ursinus, Geum rossii, Luzula spicata, Oxyria digyna, Polygonum bistortoides, Polygonum viviparum, and Potentilla rubricaulis that may indicate wet-mesic conditions during the growing season. In the more xeric stands a moss layer dominated by Polytrichastrum alpinum, Polytrichum piliferum, or Pohlia obtusifolia can be present.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: More review is needed to clarify snowbed from wetland communities dominated by Juncus drummondii and other wetland species. This alliance needs to be compared to those from ~Vancouverian-Rocky Mountain Subalpine-Alpine Snowbed, Wet Meadow & Dwarf-Shrubland Group (G520)$$. Some proto-alliances, such as Carex subnigricans - Sibbaldia procumbens Snowbed Alliance (A2703), were created for Great Basin National Park to capture some of the biogeographic variation between the main Rocky Mountain cordillera and isolated ranges in the Great Basin. These provisional alliances may provide guidance for future biogeographic-based splits of this alliance.

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: This alliance is characterized by densely tufted perennials. The graminoids share dominance with the forb to form a complete sod cover, although later melting snowbed vegetation is relatively sparse because of the extremely short growing season and sites may appear disturbed. The moss layer is often present.

Floristics: This Rocky Mountain alpine alliance includes late-melting snowbed communities characterized by a low to dense herbaceous layer dominated by diagnostic species Carex ebenea, Carex nigricans, Carex paysonis, Carex pyrenaica, Carex subnigricans, Juncus drummondii, Juncus parryi, Poa arctica ssp. grayana, Trifolium parryi, and snowbed indicator species Sibbaldia procumbens (Willard 1963, Komarkova 1976). Other high-constancy species include Antennaria alpina, Antennaria lanata, Antennaria media, Arenaria capillaris, Artemisia arctica ssp. arctica, Caltha leptosepala, Carex phaeocephala, Castilleja occidentalis, Erigeron melanocephalus, Erigeron ursinus, Geum rossii, Luzula spicata, Oxyria digyna, Polygonum bistortoides, Polygonum viviparum, and Potentilla rubricaulis that may indicate wet-mesic conditions during the growing season. In lower elevation stands Carex spectabilis (= Carex tolmiei), Deschampsia cespitosa, Hordeum brachyantherum, and Muhlenbergia richardsonis are often present (Schlatterer 1972 and Shepherd 1975, as cited in Johnston 1987). In the more xeric stands, a moss layer dominated by Polytrichastrum alpinum, Polytrichum piliferum, or Pohlia obtusifolia can be present (Komarkova 1976). Dwarf-shrub Salix nivalis may be common in some stands.

Dynamics:  Snow cover is a driving variable in alpine vegetation dynamics by protecting plant from desiccating effects of high winds during winter and providing soil moisture during the growing season (Isard 1986). Snowbed communities have the most snow cover of alpine vegetation types. Snow accumulation averages 100 cm and melts late, providing ample soil moisture and restricting the growing season to 55 days on average (Isard 1986).

Kiener (1967) states that dominance of Carex pyrenaica indicates a pioneer community within a snowpatch habitat. Sibbaldia procumbens and Erigeron are also indicators of snowpatch habits and are often present to codominant. Carex pyrenaica requires the longest snow cover; therefore, occurrences are located next to places where snow lasts the longest (mid July to mid August) (Kierner 1967).
Environmental Description:  This small-patch alliance occurs in alpine zone in the Rocky Mountain cordillera and high-elevation areas in the Colorado Plateau and Great Basin. Elevations range from 2520-3760 m depending on latitude. Stands are found in alpine areas of late-melting snowpatches that are located on lee sides of ridges, saddles, hills and knolls, and rock outcrops in snow-filled depressions. Theses late-melting snowbeds create wet-mesic soil conditions through most of the growing season and can produce lush vegetation. Stands also occur in hygric swales fed by snowmelt and seeps and on solifluction terraces on slopes where soil moisture is abundant. Snowbed communities often develop in concentric rings with later melting communities in the center. Some sites do not become snow-free until August and have a very short growing season with little time for vegetation to develop more than lichens, mosses and a few rhizomatous sedges. Slopes range from 2-49% (Willard 1963, Komarkova 1976, 1986). Rock and bare soil may cover half the ground surface. Substrates are variable and range from muck to well-drained, shallow, coarse to fine-textured mineral soil. Soils are young and poorly developed due to low soil temperature, high soil moisture during the summer, and a short growing season. Soils are classified as Entisols (Cryorthents). The average surface pH is often slightly acidic, possibly due to leaching from late-lying snow (Komarkova 1976). Parent materials are variable and may include gneiss, granite, limestone, and quartz monzonite (Komarkova 1976, 1986, Cooper et al. 1997).
Geographic Range: This small patch snowbed alliance occurs above upper treeline throughout the Rocky Mountain cordillera and alpine areas in high plateaus and ranges in the Colorado Plateau and Great Basin.

Nations: CA,US

States/Provinces:  AB, AZ, CA, CO, ID, MT, NM, NV, UT, 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.b Blackroot Sedge - Bellardi Bog Sedge - Cushion Phlox Alpine Turf & Fell-field Group G314 4.B.1.Nb.2.b
Alliance A3172 Drummond''s Rush - Parry''s Rush - Creeping Sibbaldia Rocky Mountain Alpine Snowbed Alliance A3172 4.B.1.Nb.2.b
Association CEGL001848 Boreal Sagebrush Alpine Snowbed CEGL001848 4.B.1.Nb.2.b
Association CEGL001860 Pyrenean sedge Alpine Snowbed CEGL001860 4.B.1.Nb.2.b
Association CEGL001873 Ebony Sedge - Parry''s Clover Alpine Snowbed CEGL001873 4.B.1.Nb.2.b
Association CEGL001904 Drummond''s Rush - Woolly Pussytoes Alpine Snowbed CEGL001904 4.B.1.Nb.2.b
Association CEGL001905 Drummond''s Rush - Sedge species Alpine Snowbed CEGL001905 4.B.1.Nb.2.b
Association CEGL001906 Parry''s Rush - Bear River Fleabane Alpine Snowbed CEGL001906 4.B.1.Nb.2.b
Association CEGL001924 Arctic Bluegrass Alpine Snowbed CEGL001924 4.B.1.Nb.2.b
Association CEGL001936 Parry''s Clover Alpine Snowbed CEGL001936 4.B.1.Nb.2.b
Association CEGL001969 Ross'' Avens - Creeping Sibbaldia Alpine Snowbed CEGL001969 4.B.1.Nb.2.b
Association CEGL003141 Parry''s Rush - Frosted Buckwheat Alpine Snowbed CEGL003141 4.B.1.Nb.2.b
Association CEGL003142 Parry''s Rush - Purple Mountain-heath Alpine Snowbed CEGL003142 4.B.1.Nb.2.b
Association CEGL005425 Dark Mountain Sedge - Ross'' Avens - Creeping Sibbaldia Snowbed CEGL005425 4.B.1.Nb.2.b
Association CEGL005855 Slender Mountain Sandwort / Bristly Haircap Moss Alpine Snowbed CEGL005855 4.B.1.Nb.2.b
Association CEGL005865 Payson''s Sedge - Creeping Sibbaldia Alpine Snowbed CEGL005865 4.B.1.Nb.2.b
Association CEGL005871 Parry''s Rush / Creeping Sibbaldia Alpine Snowbed CEGL005871 4.B.1.Nb.2.b
Concept Lineage: Old alliances include all or parts of V.A.5.N.g. Carex (ebenea, haydeniana) Herbaceous Alliance (A.1302), V.A.5.N.g. Poa arctica Herbaceous Alliance (A.1311), V.A.5.N.e. Carex paysonis Herbaceous Alliance (A.2640), V.A.5.N.h. Carex pyrenaica Herbaceous Alliance (A.1320), Juncus drummondii Herbaceous Alliance (A.1324), V.A.5.N.h. Juncus parryi Herbaceous Alliance (A.1325), and V.B.2.N.b. Arenaria capillaris Herbaceous Alliance (A.2630), V.B.2.N.b. Geum rossii Herbaceous Alliance (A.1645), and V.B.2.N.b. Trifolium parryi Herbaceous Alliance (A.1638). This alliance also includes a proto-alliance Carex subnigricans - Sibbaldia procumbens Snowbed Alliance (A2703 created for Great Basin National Park.

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: ? Juncus spp. Series (Johnston 1987)
= Snowbank Community (Nodum IV) (May and Webber 1982)
= Snowbank Community (Nodum IV) (May 1973)
= Snowbed Communities (Cooper et al. 1997)
Concept Author(s): D.E. May (1973)

Author of Description: K.A. Schulz

Acknowledgements: No Data Available

Version Date: 03-14-14
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