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Alpine Fell-Field

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Provisional State Rank: S5
* (see reason below)

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State Rank Reason
This system is likely to increase as perennial ice and snow disappears. Dessication and loss of alpine turf may also increase this system's occupancy.
 

General Description

This ecological system is found at alpine elevations throughout the Rocky Mountains, west into the mountainous areas of the Great Basin, and north into the Canadian Rockies. In Montana, alpine fell-fields are well represented throughout the Northern Rocky Mountains and island mountain ranges. Elevation ranges from as low as 1,981 meters (6,500 feet) in northwestern Montana to 3,200 meters (10,500 feet) in southwestern Montana. These are wind-scoured fell-fields that are often free of snow in the winter, such as ridgetops and exposed saddles, subjecting the vegetation to severe environmental stress. Soils on these windy, unproductive sites are shallow, stony, low in organic matter, and poorly developed; wind deflation often results in a gravelly pavement. This system is characterized by a very cold climate during winter, high winds, high ultraviolet radiation and surface temperatures during summer days, and a very short growing season. Ribbons of nitrogen-fixing arctic dryad (Dryas octopetala), shrubby cinquefoil (Dasiphora fruticosa) and alpine leguminous species occur on slopes subject to downward movement due to frost heaving. These ribbons or stair-step vegetation patterns form perpendicular to the slope. Plant cover can be low to moderate (15 to 50%) with exposed, stable scree and boulders constituting the remainder of cover. Most fell-field plants are highly adapted to this xeric environment and occur within these ribbons or as singular plants among exposed rocks. These species are typically cushioned, matted or succulent, or grow as flat rosettes, often with thick leaf cuticles or a dense cover of hairs. Crustose and foliose lichen species form significant cover on exposed rocks.


Diagnostic Characteristics
Vegetation cover greater than 15% but generally less than 50%; alpine to treeline elevations, scree and boulder fields, limited soil development, with organic matter restricted to vegetation patches.

Similar Systems

Range
In Montana, alpine fell-fields are well represented throughout the Northern Rocky Mountains and island mountain ranges.

Ecological System Distribution
Approximately 479 square kilometers are classified as Alpine Fell-Field in the 2013 Montana Land Cover layers.  Grid on map is based on USGS 7.5 minute quadrangle map boundaries.



Montana Counties of Occurrence
Carbon, Deer Lodge, Flathead, Gallatin, Glacier, Granite, Lake, Lewis and Clark, Lincoln, Meagher, Mineral, Missoula, Park, Pondera, Powell, Ravalli, Sanders, Silver Bow, Stillwater, Sweet Grass, Teton, Wheatland

Spatial Pattern
Large patch

Environment

Elevation ranges from as low as 1,981 meters (6,500 feet) in northwestern Montana to 3,200 meters (10,500 feet) in southwestern Montana. These wind-scoured fell-fields are often free of snow in the winter, occurring on ridgetops and exposed saddles and subjecting the vegetation to severe environmental stress. Soils on these windy, unproductive sites are shallow, stony, low in organic matter, and poorly developed; wind deflation often results in a gravelly pavement. This system is characterized by a very cold climate during winter, high winds, high ultraviolet radiation and high surface temperatures during summer days, and a very short growing season. Exposed, stable scree and isolated boulders constitute at least half of the cover. Soil development is very limited, and derived from a variety of parent materials. It is usually gravelly or rocky, and can be acidic or calcareous. Organic matter is only found in limited quantities within vegetation ribbons and patches of dwarf, woody species.


Vegetation

Ribbons of nitrogen-fixing arctic dryad (Dryas octopetala), shrubby cinquefoil (Dasiphora fruticosa) and alpine leguminous species occur on slopes subject to downward movement due to frost heaving. Common alpine legumes include silver lupine (Lupinus argenteus), yellow sweetvetch (Hedysarum sulphurescens), alpine milkvetch (Astragaulus alpinus), Bourgov’s milkvetch (Astragaulus bourgovii), boreal crazyweed (Oxtropis borealis), silky crazyweed (Oxytropis sericea), and in southwestern Montana, alpine clover (Trifolium species). These ribbons or stair-step vegetation patterns form perpendicular to the slope. Plants accumulate litter within the mats and improve soil fertility, thus facilitating additional species colonization within the mats. Plant cover can be low to moderate (15 to 50%) but plants are is rarely more than 9 centimeters (3.6 inches) high.

Other forbs can occur with the mats, singly or in small patches among the exposed rocks. In northwestern Montana, common forbs include yarrow (Achillea millefolium), penstemon (Penstemon species), phacelia (Phacelia species), alpine fireweed (Chamerion latifolium), moss campion (Silene acaulis),twinflower sandwort (Minuartia obtusiloba), alpine goldenrod (Solidago multiradiata), sky pilot (Polemonium viscosum), cut-leaf daisy (Erigeron compositus), draba (Draba species), arnica (Arnica alpina), alpine pussytoes (Antennaria species), one-stem fleabane (Erigeron simplex), sibbaldia (Sibbaldia procumbens), diverse leaf cinquefoil (Potentilla diversifolia), moss campion (Silene acaulis), lousewort (Pedicularis species), elegant death camas (Zigadenus elegans), alpine bistort (Polygonum bistortoides), rock jasmine buckwheat (Eriogonum androsaceum), alpine buckwheat (Eriogonum ovalifolium), viviparous bistort (Polygonum viviparum), alpine forget-me-not (Myosotis alpestris) and Siberian aster (Symphyotrichum sibiricus). Many of the cushion species are very long lived, and are often well-adapted to limited available water because of deep, fleshy taproots. These species can persist for decades. Other low, mat forming woody species such as arctic willow (Salix arctica), snow willow (Salix nivalis), rock willow (Salix vestita), and in the island mountain ranges, bearberry (Arctostaphylos uva-ursi), are usually present among the exposed rocks. Several northern Rocky Mountain endemic species, species of concern, and potential species of concern inhabit alpine fell-field communities

Cover of sedges, rushes, woodrushes and grasses is usually lower than forb cover, but often includes species such as Dunhead sedge (Carex phaeocephala), spike sedge (Carex nardina), curly sedge (Carex ruprestris), northern single spike sedge (Carex scirpoidea), black and white sedge (Carex albonigra), spiked woodrush (Luzula spicata), Piper’s woodrush (Luzula piperi), Drummond’s rush (Juncus drummondii), alpine blue grass (Poa alpina), spike trisetum (Trisetum spicatum) and slender wheatgrass (Elymus trachycaulus). In southwestern Montana fell-field communities, other species such as blackroot sedge (Carex elynoides), Parry’s rush (Juncus parryi), Idaho fescue (Festuca idahoenisis), spike fescue (Festuca kingii) and sheep fescue (Festuca ovina) become common (Cooper et al., 1999). Diverse crustose and foliose lichen cover is often high on exposed rocks. Fern allies such as lesser spikemoss (Selaginella densa) can be locally abunant in some areas.

Adjacent to this system is a mosaic of alpine plant communities that vary in composition depending on soil development, snow retention, subterranean hydrology and localized topography. Alpine turf and snow bed communities occur on more level or concave sites with greater soil development adjacent to fell-fields. Alpine bedrock, talus and unstable scree fields and ice fields often occur adjacent to this system around mountain summits. Fell-fields are often bordered by subalpine forest krummolz mats and small patches of subalpine forests growing at their upper elevational limit on protected sites. The most common forest association in Montana is whitebark pine-subalpine fir (Pinus albicaulis-Abies lasiocarpa). In scattered locations on north and east facing aspects, fell-fields can be bordered by small patches of alpine larch (Larix lyallii).


Alliances and Associations
Alliances
  • (A.1630) Alpine Stitchwort Herbaceous Alliance
  • (A.927) American Red Raspberry Shrubland Alliance
  • (A.2638) Black-and-white Scale Sedge Herbaceous Alliance
  • (A.1635) Creeping Glow-wort Herbaceous Alliance
  • (A.1651) Cushion Phlox Herbaceous Alliance
  • (A.1636) Cushion Pink Herbaceous Alliance
  • (A.1326) Pacific Bog Sedge Herbaceous Alliance
  • (A.1638) Parry's Clover Herbaceous Alliance
  • (A.2640) Payson's Sedge Herbaceous Alliance
  • (A.1645) Ross' Avens Herbaceous Alliance
  • (A.1534) Shrubby-cinquefoil Shrub Herbaceous Alliance

Dynamic Processes
Historically, stand-replacing fires occurred infrequently in adjacent associated upper elevation subalpine woodlands (Arno 1980). Lightning strikes can cause fire within fell-fields, although severity and spread is usually variable. Major disturbances can include fire, high elevation mining, heavy recreational use, and grazing. Changing climatic patterns will impact this system and the distribution of peripheral species, northern Rocky Mountain endemics and rare species that occur within it.

Management
This system is fragile due to its extremely limited growing season and soil development. Species in these systems are generally slow growing and decrease in cover and vigor in areas of trampling or grazing.

Restoration Considerations
Generally, grazing and human disturbances are very limited in this system due to inaccessibility or low forage cover.

Species Associated with this Ecological System
  • Details on Creation and Suggested Uses and Limitations
    How Associations Were Made
    We associated the use and habitat quality (high, medium, or low) of each of the 82 ecological systems mapped in Montana for vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
    1. Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2001, Adams 2003, and Werner et al. 2004);
    2. Evaluating structural characteristics and distribution of each ecological system relative to the species’ range and habitat requirements;
    3. Examining the observation records for each species in the state-wide point database associated with each ecological system;
    4. Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of “observations versus availability of habitat”.
    Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.  In general, species were associated as using an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.  However, species were not associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system, even if point observations were associated with that system.  High, medium, and low habitat quality was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species in the literature.  The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignments of habitat quality.  If you have any questions or comments on species associations with ecological systems, please contact Bryce Maxell at bmaxell@mt.gov or (406) 444-3655.

    Suggested Uses and Limitations
    Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.  These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at: http://mtnhp.org/requests/default.asp) or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.  Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.  Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.  Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).  Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species’ known geographic range.

    Literature Cited
    • Adams, R.A.  2003.  Bats of the Rocky Mountain West; natural history, ecology, and conservation.  Boulder, CO: University Press of Colorado.  289 p.
    • Dobkin, D. S.  1992.  Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34.  Missoula, MT.
    • Foresman, K.R.  2001.  The wild mammals of Montana.  Special Publication No. 12.  Lawrence, KS: The American Society of Mammalogists.  278 p.
    • Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998.  Montana atlas of terrestrial vertebrates.  Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT.  1302 p.
    • Hutto, R.L. and J.S. Young.  1999.  Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32.  72 p.
    • Maxell, B.A.  2000.  Management of Montana’s amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species.  Report to U.S. Forest Service Region 1.  Missoula, MT: Wildlife Biology Program, University of Montana.  161 p.
    • Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath.  2004.  Amphibians and reptiles of Montana.  Missoula, MT: Mountain Press Publishing Company. 262 p.

Original Concept Authors
Natureserve Western Ecology Group

Montana Version Authors
L.K. Vance, T. Luna

Version Date
5/21/2010

References
  • Classification and Map Identifiers

    Cowardian Wetland Classification: Not applicable

    National Vegetation Classification Standard:
    Class Polar and High Montane Vegetation
    Subclass Temperate and Boreal Alpine Vegetation
    Formation Alpine Scrub, Forb Meadow and Grassland
    Division Western North America Alpine Scrub, Forb Meadow and Grassland
    Macrogroup Rocky Mountain Alpine Scrub, Forb Meadow and Grassland

    NatureServe Identifiers:
    Element Global ID 28647
    System Code CES306.811, Rocky Mountain Alpine Fell-Field

    ReGAP:
    7116: Rocky Mountain Alpine Fell-Field


  • Additional ReferencesLegend:   View WorldCat Record   View Online Publication
    Do you know of a citation we're missing?
    • Arno, S. F. 1980. Forest fire history in the northern Rockies. Journal of Forestry 78(8):460-465.
    • Cooper, S. V., C. Jean, and B. L. Heidel. 1999. Plant associations and related botanical inventory of the Beaverhead Mountains Section, Montana. Unpublished report to the Bureau of Land Management. Montana Natural Heritage Program, Helena. 235 pp.

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Citation for data on this website:
Alpine Fell-Field — Rocky Mountain Alpine Fell-Field.  Montana Field Guide.  Retrieved on April 20, 2014, from http://FieldGuide.mt.gov/displayES_Detail.aspx?ES=7116
 
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