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A3968 Abies lasiocarpa - Populus tremuloides / Acer glabrum Central Rocky Mountain Avalanche Chute Shrubland Alliance
Type Concept Sentence: This shrubland alliance is composed of a moderately dense to dense, diverse mix of deciduous shrubs and broken and stunted trees such as Abies lasiocarpa, Acer glabrum, Alnus viridis ssp. sinuata, Alnus incana, Amelanchier alnifolia, Populus tremuloides, Ribes lacustre, Rubus parviflorus, Sorbus scopulina, and on drier sites Pseudotsuga menziesii. It is found within avalanche chutes at a broad range of elevations within the zone of continuous forest in the upper montane and subalpine zones of the central Rocky Mountains.
Common (Translated Scientific) Name: Subalpine Fir - Quaking Aspen / Rocky Mountain Maple Central Rocky Mountain Avalanche Chute Shrubland Alliance
Colloquial Name: Central Rocky Mountain Subalpine Fir - Quaking Aspen Avalanche Chute Shrubland
Hierarchy Level: Alliance
Type Concept: Stands of this shrubland alliance are composed of a moderately dense to dense, diverse mix of deciduous shrubs and broken and stunted trees. This canopy may be codominated by Abies lasiocarpa, Acer glabrum, Alnus viridis ssp. sinuata, Alnus incana, Amelanchier alnifolia, Populus tremuloides, Ribes lacustre, Rubus parviflorus, Sorbus scopulina, and on drier sites Pseudotsuga menziesii. Where avalanches occur annually or more often, conifers are rare and brushy deciduous trees and shrubs are common. Where avalanches are less frequent, stands dominated by conifers less than 4 m tall develop. The ground layer is composed of graminoids and forbs. The forb component is often very diverse, and mesic forbs prevail. Chamerion angustifolium was present in all sampled plots, a good indicator of periodic disturbance that characterizes this alliance. Other common to abundant species include Angelica arguta, Artemisia ludoviciana, Calamagrostis canadensis, Calamagrostis rubescens, Carex geyeri, Elymus glaucus, Erythronium grandiflorum, Galium triflorum, Heracleum maximum, Osmorhiza occidentalis, Pteridium aquilinum, Solidago canadensis, Thalictrum occidentale, Valeriana sitchensis, and Veratrum viride. This shrubland alliance is found within avalanche chutes at a broad range of elevations within the zone of continuous forest in the upper montane and subalpine zones of the central Rocky Mountains, from Wyoming north and west into British Columbia and Alberta. Stands are located in avalanche tracks and runout zones and can occur on any aspect, but are more common on southeast- to southwest-facing slopes where unstable snowpack conditions frequently occur. Sites are often mesic because avalanche paths are often in stream gullies. Substrate is variable depending on parent materials, but is typically shallow and rocky. Adjacent vegetation may include subalpine forests dominated by Abies lasiocarpa, Picea engelmannii, or Pseudotsuga menziesii, and subalpine meadows.
Diagnostic Characteristics: Vegetation is characterized by a woody canopy of dwarfed and damaged conifer and deciduous trees and/or deciduous shrubs. Characteristic dominant species include dwarfed Abies lasiocarpa, Acer glabrum, Alnus viridis ssp. sinuata, Alnus incana, Amelanchier alnifolia, Populus tremuloides, Ribes lacustre, Rubus parviflorus, and Sorbus scopulina. Associated herbaceous species include graminoids Calamagrostis canadensis, Calamagrostis rubescens, Carex geyeri, and Elymus glaucus and forbs Angelica arguta, Artemisia ludoviciana, Chamerion angustifolium, Erythronium grandiflorum, Eurybia conspicua, Galium triflorum, Heracleum maximum, Myosotis asiatica, Osmorhiza occidentalis, Pteridium aquilinum, Solidago canadensis, Thalictrum occidentale, Valeriana sitchensis, Veratrum viride, and Xerophyllum tenax. Mosses are often present.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: More inventory is needed to determine the range of vegetation in the alliance, because both codominant species are widespread in the Rocky Mountains and likely occur outside of the central Rocky Mountains. Some associations included in this alliance also occur outside frequently disturbed avalanche chutes such ~Rubus parviflorus / Chamerion angustifolium - Heracleum maximum Shrubland (CEGL001127)$$, that is reported to occur below the timberline zone on sites where the snow-free season is long, typically starting in April-May (Franklin and Dyrness 1973). Non-avalanche zone stands in these associations need further review.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: These shrublands have a canopy dominated by dwarfed, disturbance-damaged, needle-leaved evergreen trees and cold-deciduous shrubs/small trees up to 5 m in height. The herbaceous layer is dominated by upright forbs or sod-forming graminoids. The herbaceous cover increases with increasing soil moisture. Mosses and ferns are often present.
Floristics: Stands are composed of a moderately dense to dense, often diverse mix of deciduous shrubs and broken and stunted trees. Where avalanches occur annually or more often, conifers are rare and brushy deciduous trees and shrubs are common. Where avalanches are less frequent, stands dominated by conifers less than 4 m tall develop. Abies lasiocarpa and Populus tremuloides are frequently present to codominate in the uppermost canopy, but stands may be dominated by Acer glabrum, Alnus incana, Alnus viridis ssp. sinuata, Amelanchier alnifolia, Ribes lacustre, Rubus parviflorus, Sorbus scopulina, and on drier sites Pseudotsuga menziesii. Other common shrubs include Crataegus douglasii, Lonicera utahensis, Mahonia repens, Paxistima myrsinites, Prunus pensylvanica, Prunus virginiana, Salix planifolia, Salix scouleriana, Shepherdia canadensis, Symphoricarpos albus, and Symphoricarpos oreophilus. Trees from the surrounding forests are common on the edges of the avalanche tracks and in runout zones. Additional tree species present may include Betula papyrifera, Picea engelmannii, Pinus contorta, and Pinus ponderosa . The ground cover is moderately dense to dense and composed of graminoids such as Calamagrostis canadensis, Calamagrostis rubescens, Carex geyeri, and Elymus glaucus. The forb component is often very diverse, and mesic forbs are most common. Chamerion angustifolium (= Epilobium angustifolium) was present in all sampled plots, a good indicator of periodic disturbance that characterizes this alliance. Other common to abundant species include Angelica arguta, Artemisia ludoviciana, Erythronium grandiflorum, Eurybia conspicua (= Aster conspicuus), Galium triflorum, Heracleum maximum, Myosotis asiatica (= Myosotis alpestris), Osmorhiza occidentalis, Pteridium aquilinum, Solidago canadensis, Thalictrum occidentale, Valeriana sitchensis, Veratrum viride, and Xerophyllum tenax. Mosses and ferns are often present.
Dynamics: Disturbance by avalanches prevents tall forests from growing on these sites. Flexible-stemmed deciduous trees and shrubs are more tolerant of this snow movement than conifers. Where avalanches are frequent, stands develop that are dominated by dwarfed/broken conifers (less than 4 m tall). Where avalanches occur annually or more often, only brushy deciduous trees and shrubs are present (Butler 1979).
Environmental Description: This shrubland alliance is found within avalanche chutes at a broad range of elevations within the zone of continuous forest in the upper montane and subalpine zones of the central Rocky Mountains. Elevations range from 950-2396 m (3100-7860 feet). Climate is temperate with extremely cold winters and cool summers. Mean annual precipitation ranges from 50-70 cm and occurs mostly as snow. Stands are located in avalanche tracks and runout zones. Slopes range from 15-60%. These communities can occur on any aspect, but are more common where unstable snowpack conditions frequently occur, such as southeast aspects where snow cornices develop because of prevailing northwesterly winds, and south- to southwest-facing slopes because of suncrust formation (Butler 1979). Sites are often mesic because avalanche paths are often in stream gullies. Substrate is variable depending on parent materials, but is typically shallow and rocky. Soils are rapidly to well-drained loamy sands, sandy loams, or silt loams, strongly acidic to neutral, and characterized as Orthic and Cumulic Regosols developed on fluvial and colluvial landforms. Soils tend to be dark, weakly developed soils on colluvial and glacio-fluvial landforms with high gravel and rock content. Litter dominates the ground surface with 40-85% cover. Frequent avalanches maintain the shrubby structure of this deciduous shrubland. Adjacent vegetation may include subalpine forests dominated by Abies lasiocarpa, Picea engelmannii, or Pseudotsuga menziesii, and subalpine meadows.
Geographic Range: This alliance occurs within avalanche chutes at a broad range of elevations within the zone of continuous forest in the montane and subalpine zones of the central Rocky Mountains from Wyoming north and west into Alberta and British Columbia.
Nations: CA,US
States/Provinces: AB, BC, CA, CO, MT, NV, WA, WY
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.900019
Confidence Level: Low
Confidence Level Comments: No Data Available
Grank: GNR
Greasons: No Data Available
Concept Lineage: A.915 (in part), A.913 (in part), A.931 (in part), A.970 (in part), and A.1052. This new alliance includes associations from Old Alliance III.B.2.N.a. Acer glabrum Shrubland Alliance (A.915), Old Alliance III.B.2.N.a. Amelanchier alnifolia Shrubland Alliance (A.913), and Old Alliance III.C.2.N.a. Abies lasiocarpa - Acer glabrum Shrubland Alliance (A.1052), Old Alliance III.B.2.N.d. Ribes lacustre Temporarily Flooded Shrubland Alliance (A.970), and Old Alliance III.B.2.N.b. Rubus parviflorus Shrubland Alliance (A.931).
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: No Data Available
- Butler, D. R. 1979. Snow avalanche path terrain and vegetation, Glacier National Park, Montana. Arctic and Alpine Research 11:17-32.
- Douglas, G. W. 1972. Subalpine plant communities of the western North Cascades, Washington. Arctic and Alpine Research 4:147-166.
- Faber-Langendoen, D., J. Drake, M. Hall, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, M. Russo, K. Schulz, L. Sneddon, K. Snow, and J. Teague. 2013-2019b. Screening alliances for induction into the U.S. National Vegetation Classification: Part 1 - Alliance concept review. NatureServe, Arlington, VA.
- Franklin, J. F., and C. T. Dyrness. 1973. Natural vegetation of Oregon and Washington. General Technical Report PNW-8. USDA Forest Service, Pacific Northwest Forest and Range Experiment Station, Portland, OR. 417 pp.
- Hop, K., M. Reid, J. Dieck, S. Lubinski, and S. Cooper. 2007. U.S. Geological Survey-National Park Service Vegetation Mapping Program: Waterton-Glacier International Peace Park. U.S. Geological Survey, Upper Midwest Environmental Sciences Center, La Crosse, WI. 131 pp. plus Appendices A-L.
- Reid, M. S., S. V. Cooper, and G. Kittel. 2004. Vegetation classification of Waterton-Glacier International Peace Park. Final report for USGS-NPS Vegetation Mapping Program, International Peace Park Mapping Project. NatureServe, Arlington VA.