Print Report
A3154 Minuartia obtusiloba - Paronychia pulvinata - Silene acaulis Alpine Fell-field Alliance
Type Concept Sentence: Vegetation ranges from sparse to moderately low herbaceous cover dominated by cushion plants with lesser cover of graminoid species. This alpine alliance includes wind-scoured fell-fields and stabilized scree and talus fields that are typically free of snow during the winter as they are found on ridgetops, upper slopes or exposed saddles. It occurs in higher elevation alpine zone above upper treeline throughout the Rocky Mountain cordillera and alpine areas of high plateaus and ranges in the Colorado Plateau and Great Basin.
Common (Translated Scientific) Name: Twin-flower Sandwort - Rocky Mountain Nailwort - Moss Campion Alpine Fell-field Alliance
Colloquial Name: Rocky Mountain Cushion Plant Alpine Fell-field
Hierarchy Level: Alliance
Type Concept: This Rocky Mountain alpine alliance is composed of sparse to moderate plant cover, which ranges from 10-50%, with exposed gravel and rock making up the rest of the cover. The herbaceous layer is characterized by a sparse to moderate herbaceous layer dominated by cushion plants with lesser cover of graminoids. Diagnostic and often dominant species are Aquilegia scopulorum, Carex albonigra, Carex arapahoensis, Eriogonum caespitosum, Eriogonum holmgrenii, Geum rossii, Ivesia gordonii, Minuartia obtusiloba, Myosotis asiatica, Paronychia pulvinata, Phlox pulvinata, Potentilla ovina, Potentilla sierrae-blancae, Silene acaulis, Sphaeromeria argentea, Trifolium dasyphyllum, and Trifolium nanum. These plants are adapted to harsh conditions with their cushioned or matted, frequently succulent, flat-to-the-ground rosettes, and are often densely haired and thickly cutinized. Widespread alpine turf species such as Carex rupestris or Geum rossii may be present but usually with low cover. Great Basin alpine areas tend to be drier and include some lower elevation species common in desert scrub such as Poa secunda. The moss Selaginella densa is often present. This alliance occurs in higher elevation alpine zone above upper treeline throughout the Rocky Mountain cordillera and alpine areas of high plateaus and ranges in the Colorado Plateau and Great Basin. It includes wind-scoured fell-fields and stabilized scree and talus fields that are typically free of snow during the winter as they are found on ridgetops, upper slopes or exposed saddles. Stands are usually located on flat to gently sloping ridges and summits in the upper alpine zone between 1900 and 3865 m elevation depending on latitude. The ridgetops are subject to extremely high winds and are blown free of snow in winter. The ground is covered with rocks that have been stabilized for a long period of time, often forming a gravelly pavement. The sites are called fell-fields and differ from talus or scree which are located on steeper slopes and are unstable and often moving. The soils are poorly developed and have little organic matter.
Diagnostic Characteristics: This alpine field-field alliance is characterized by dominance of cushion plants. Total vegetation cover ranges from 10-50%, with exposed rocks making up the rest. Characteristic species include Aquilegia scopulorum, Carex albonigra, Carex arapahoensis, Eriogonum caespitosum, Eriogonum holmgrenii, Geum rossii, Ivesia gordonii, Minuartia obtusiloba, Myosotis asiatica, Paronychia pulvinata, Potentilla ovina, Potentilla sierrae-blancae, Silene acaulis, Sphaeromeria argentea, Trifolium dasyphyllum, and Trifolium nanum.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: Some associations need more review and possibly splitting: ~Carex ebenea - Trifolium parryi Alpine Snowbed (CEGL001873)$$, ~Carex haydeniana Alpine Turf (CEGL001875)$$, ~Carex spp. - Geum rossii Alpine Turf (CEGL001870)$$, ~Trifolium dasyphyllum Alpine Fell-field (CEGL001935)$$, and ~Trifolium parryi Alpine Snowbed (CEGL001936)$$ are broadly defined floristically and occur in both fell-fields and dry turf.
Some proto-alliances, such as Poa secunda - Arenaria congesta - Cirsium eatonii Herbaceous Alliance [Provisional] (A2041) and Aquilegia scopulorum - Eriogonum holmgrenii - Geum rossii Alpine Fell-field Herbaceous Alliance (A2702), 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.
Some proto-alliances, such as Poa secunda - Arenaria congesta - Cirsium eatonii Herbaceous Alliance [Provisional] (A2041) and Aquilegia scopulorum - Eriogonum holmgrenii - Geum rossii Alpine Fell-field Herbaceous Alliance (A2702), 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: Vegetation included in this alliance has relatively sparse cover that is dominated by low cushion plants sometimes forming prostrate mats of herbaceous vegetation. Short perennial graminoids are also present.
Floristics: This Rocky Mountain alpine alliance is composed of sparse to moderate plant cover, which ranges from 10-50%, with exposed gravel and rock making up the rest of the cover. The herbaceous layer is dominated by cushion plants, which are adapted to these harsh conditions with their cushioned or matted, frequently succulent, flat-to-the-ground rosettes, and are often densely haired and thickly cutinized. Graminoids are less abundant than in turf and meadows, although there are several graminoid species that are characteristic of fell-field. Diagnostic and often dominant species are Aquilegia scopulorum, Carex albonigra, Carex arapahoensis, Eriogonum caespitosum, Eriogonum holmgrenii, Geum rossii, Ivesia gordonii, Minuartia obtusiloba, Myosotis asiatica, Paronychia pulvinata, Phlox pulvinata, Potentilla ovina, Potentilla sierrae-blancae, Silene acaulis, Sphaeromeria argentea, Trifolium dasyphyllum, and Trifolium nanum. Widespread, dominant alpine turf species such as Carex elynoides, Carex rupestris, or Kobresia myosuroides are often present, but with lower cover. There are many associate species, including Agoseris glauca, Artemisia frigida, Artemisia pattersonii, Eriogonum ovalifolium, Festuca brachyphylla, Festuca campestris, Geum rossii, Helictotrichon mortonianum, Ionactis alpina, Luzula spicata, Oxytropis parryi, Penstemon pumilus, Phlox hoodii ssp. muscoides, Poa cusickii ssp. epilis (= Poa epilis), Potentilla diversifolia, Smelowskia calycina, Solidago simplex var. spathulata, Tetraneuris acaulis, Tetraneuris grandiflora, and Trisetum spicatum. Basin alpine areas tend to be drier and include some lower elevation species common in desert scrub, such as Poa secunda. The cryptogam layer has a high diversity of mainly lichen species. Athallia holocarpa (= Caloplaca holocarpa), Candelariella aurella, Cetraria aculeata (= Cornicularia aculeata), Dactylina madreporiformis, Flavocetraria nivalis (= Cetraria nivalis), Thamnolia subuliformis, and Vulpicida juniperina (= Cetraria tilesii) are the most common lichens, and Polytrichum piliferum and Selaginella densa are the most common moss species.
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). Fell-field communities occur on exposed sites and have the least snow cover of alpine vegetation types. Sites typically have discontinuous snow cover or are blown snow-free much of the winter, exposing the alpine plants to extreme cold and the desiccating effects of high winds. The limited snow accumulation (<10 cm) melts early and does not provide much soil moisture for the relatively long growing season (>3 months) (Isard 1986).
Environmental Description: Vegetation in this alliance occurs in the alpine tundra of the Rocky Mountains. The climate regime is continental, with long, cold winters and short summers with frequent afternoon thunderstorms. Strong westerly winds are common in the winter and spring. Stands are usually located on flat to gently sloping ridges and summits in the upper alpine zone between 1900 and 3865 m elevation depending on latitude. The ridgetops are subject to extremely high winds and are blown free of snow in winter. The ground is covered with rocks that have been stabilized for a long period of time, often forming a gravelly pavement. The sites are called fell-fields and differ from talus or scree which are located on steeper slopes and are unstable and often moving. The soils are poorly developed, have little organic matter, and are classified as Inceptisols (Cryochrepts). Soils have variable texture, ranging from sandy loam to clay and are derived from a variety of metamorphic or igneous rocks, as well as sedimentary rocks such as limestone.
Geographic Range: This fell-field alliance occurs in higher elevation alpine zone above upper treeline throughout the Rocky Mountain cordillera and alpine areas of 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, WA, WY
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.899279
Confidence Level: Moderate
Confidence Level Comments: No Data Available
Grank: GNR
Greasons: No Data Available
Concept Lineage: This alliance includes all or parts of the following old alliances IV.A.1.N.c. Paronychia pulvinata Dwarf-shrubland Alliance (A.1085) V.B.2.N.b. Geum rossii Herbaceous Alliance (A.1645), V.B.2.N.b. Ivesia gordonii Herbaceous Alliance (A.1627), V.A.5.N.g. Carex albonigra Herbaceous Alliance (A.2638), V.A.5.N.g. Carex rupestris Herbaceous Alliance (A.1307), V.A.5.N.h. Carex arapahoensis Herbaceous Alliance (A.1319), V.B.2.N.b. Minuartia obtusiloba Herbaceous Alliance (A.1630), V.B.2.N.b. Phlox pulvinata Herbaceous Alliance (A.1651), V.B.2.N.b. Potentilla sierrae-blancae Herbaceous Alliance (A.1652), V.B.2.N.b. Silene acaulis Herbaceous Alliance (A.1636), V.B.2.N.b. Sphaeromeria argentea Herbaceous Alliance (A.1654), and V.B.2.N.b. Trifolium (dasyphyllum, nanum) Herbaceous Alliance (A.1637). This alliance also includes some proto-alliances such as Poa secunda - Arenaria congesta - Cirsium eatonii Herbaceous Alliance [Provisional] (A2041) and Aquilegia scopulorum - Eriogonum holmgrenii - Geum rossii Alpine Fell field Herbaceous Alliance (A2702) from Great Basin National Park.
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: = Dry fellfield (Nodum I) (May 1973)
= Dry fellfield (Nodum I) (May and Webber 1982)
= Turf Communities (Cooper et al. 1997)
= Dry fellfield (Nodum I) (May and Webber 1982)
= Turf Communities (Cooper et al. 1997)
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