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A4332 Arctic Acidic Dryas Dwarf-shrub Tundra Alliance
Type Concept Sentence: This alliance is defined by tundra vegetation dominated by the dwarf, broad-leaved evergreen shrub species, Dryas octopetala and/or Dryas integrifolia often in combination with dwarf willows or ericaceous shrubs occurring in the arctic and subarctic regions of Alaska and Canada.
Common (Translated Scientific) Name: Arctic Acidic Dryas Dwarf-shrub Tundra Alliance
Colloquial Name: Arctic Acidic Dryas Dwarf-shrub Tundra
Hierarchy Level: Alliance
Type Concept: This tundra alliance is defined by vegetation dominated by the dwarf, broad-leaved evergreen shrub species Dryas octopetala and/or Dryas integrifolia. In addition to its dominant species, Dryas dwarf-shrub tundra supports high constancy of the dwarf willows Salix reticulata, Salix arctica, Salix phlebophylla, the ericaceous shrubs Cassiope tetragona and Vaccinium uliginosum, the grass Anthoxanthum monticola ssp. alpinum, the sedge Carex scirpoidea, and the lichens Thamnolia vermicularis and Flavocetraria nivalis. Dryas vegetation is common on exposed, windswept areas with little winter snow cover throughout arctic and subarctic Alaska, Canada, and possibly parts of Greenland. Types dominated by Dryas octopetala appear to be more common at high elevation on alpine slopes and ridges, whereas types dominated by Dryas integrifolia are more common at high latitude in the Arctic as well as on inactive floodplains and in drained lake basins. Substrates are typically mineral and are non-acidic to circumneutral. Patch size is small to matrix-forming.
Diagnostic Characteristics: This alliance is defined by tundra vegetation dominated by the dwarf, broad-leaved, evergreen shrub species Dryas octopetala and/or Dryas integrifolia in the arctic and subarctic regions of Alaska and Canada.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: Alpine regions in the arctic and subarctic regions of Alaska and Canada are included here. The dominance by Dryas octopetala versus Dryas integrifolia or the acidic versus non-acidic Dryas types may provide alliance-level distinctions. The applicability of this group concept in Canada needs critical review.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: This alliance is represented by dwarf, broad-leaved, evergreen shrubs in the Dryas genus with growth forming a few centimeter-thick mat; tussocks are not present.
Floristics: The dwarf-shrubs Dryas integrifolia and/or Dryas octopetala dominate the shrub layer with at least 20% cover. In addition to these dominant species, the alliance supports high constancy of the dwarf-shrubs Salix reticulata, Salix arctica, Salix phlebophylla, the ericaceous shrubs Cassiope tetragona and Vaccinium uliginosum, the grass Anthoxanthum monticola ssp. alpinum, the sedge Carex scirpoidea, and the lichens Thamnolia vermicularis and Flavocetraria nivalis. When split by dominance, the Dryas octopetala variant is marginally indicated by the grass Anthoxanthum monticola ssp. alpinum, whereas the Dryas integrifolia variant is significantly indicated by Arctagrostis latifolia, Papaver species, and marginally indicated by Polygonum viviparum.
Dynamics: While this alliance forms in regions of continuous permafrost, it is likely that a deep active layer, either due to ice-poor soils in the alpine or taliks surrounding waterbodies in the Arctic diminishes the effects of permafrost processes such as the formation of tussocks. The successional status of this type is thought to be intermediate. In the alpine, exposure may hold this type in a mid-seral state; however, in the Arctic, gradual accumulation of organic material may facilitate transition to a low shrubland.
Environmental Description: This alliance is common on exposed, windswept areas with little winter snow cover throughout arctic and subarctic Alaska, Canada, and possibly parts of Greenland. Types dominated by Dryas octopetala appear to be more common at high elevation on alpine slopes and ridges, whereas types dominated by Dryas integrifolia are more common at high latitude on inactive floodplains and in drained lake basins. Where Dryas species co-occur, Dryas octopetala occupies drier, more exposed microsites with Dryas integrifolia restricted to wetter, more protected microsites such as swales or areas of late-lying snow. Patch size is small to matrix-forming. Substrates are typically mineral and non-acidic to circumneutral.
Geographic Range: This alliance occurs throughout arctic and subarctic Alaska, and possibly through much of arctic and subarctic Canada into Greenland.
Nations: CA,GL?,IS,NO,RU,US
States/Provinces: AK, LB?, MB, NT?, NU?, QC?, YT?
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.1042050
Confidence Level: Low
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.2 Polar Tundra & Barrens Formation | F031 | 4.B.2 |
| Division | 4.B.2.Xa Arctic Tundra & Barrens Division | D044 | 4.B.2.Xa |
| Macrogroup | 4.B.2.Xa.2 Feltleaf Willow - Eight-petal Mountain-avens - Tussock Cottongrass Tundra Macrogroup | M173 | 4.B.2.Xa.2 |
| Group | 4.B.2.Xa.2.b Arctic Dwarf-shrub Tundra Group | G896 | 4.B.2.Xa.2.b |
| Alliance | A4332 Arctic Acidic Dryas Dwarf-shrub Tundra Alliance | A4332 | 4.B.2.Xa.2.b |
Concept Lineage: No Data Available
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: > Dryas integrifolia - Carex bigelowii (Entireleaf mountain-avens - Bigelow''s sedge) (Jorgenson 1984)
> Dryas octopetala - Carex scirpoidea (Eightpetal mountain-avens - northern singlespike sedge) (Gjaerevoll 1954)
> Dryas octopetala - Cassiope tetragona (Eightpetal mountain-avens - white arctic mountain heather) (Craighead et al. 1988)
> Dryas octopetala - Potentilla uniflora (Eightpetal mountain-avens - oneflower cinquefoil) (Jorgenson et al. 2004)
> Alpine Syntaxa 29-32 Dryas communities (Cooper 1986c)
> II.D.1.a - Dryas tundra (Viereck et al. 1992)
> II.D.1.b - Dryas-sedge dwarf shrub tundra (Viereck et al. 1992)
> II.D.1.c - Dryas-sedge tundra (Viereck et al. 1992)
> P2.1 - Prostrate dwarf-shrub lichen communities (#15) growing on St. Matthew Island (Raynolds et al. 2006a)
> Dryas octopetala - Carex scirpoidea (Eightpetal mountain-avens - northern singlespike sedge) (Gjaerevoll 1954)
> Dryas octopetala - Cassiope tetragona (Eightpetal mountain-avens - white arctic mountain heather) (Craighead et al. 1988)
> Dryas octopetala - Potentilla uniflora (Eightpetal mountain-avens - oneflower cinquefoil) (Jorgenson et al. 2004)
> Alpine Syntaxa 29-32 Dryas communities (Cooper 1986c)
> II.D.1.a - Dryas tundra (Viereck et al. 1992)
> II.D.1.b - Dryas-sedge dwarf shrub tundra (Viereck et al. 1992)
> II.D.1.c - Dryas-sedge tundra (Viereck et al. 1992)
> P2.1 - Prostrate dwarf-shrub lichen communities (#15) growing on St. Matthew Island (Raynolds et al. 2006a)
- Boggs, K., A. Garibaldi, J. Stevens, J. Grunblatt, and T. Helt. 2001. Denali National Park and Preserve landcover mapping project. Volume 2: Landcover classes and plant associations. Natural Resource Technical Report NPS/DENA/NRTR--2001/002. National Park Service, Fort Collins, CO. 164 pp.
- Cooper, D. J. 1986c. Arctic-alpine tundra vegetation of the Arrigetch Creek Valley, Brooks Range, Alaska. Phytocoenologia 14(4):647-555.
- Craighead, J. J., F. L. Craighead, D. J. Craighead, and R. L. Redmond. 1988. Mapping arctic vegetation in northwest Alaska using Landsat MSS Imagery. National Geographic Research 4(4):496-527.
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- Gjaerevoll, O. 1954. Kobresieto-dryadion in Alaska. Nytt Magasin för Botanikk 3:51-54.
- Jorgenson, M. T. 1984. The response of vegetation to landscape evolution on glacial till near Toolik Lake, Alaska. Pages 134-142 in: Inventorying forest and other vegetation of the high latitude and high altitude regions. Proceedings of an International Symposium, Society of American Foresters Regional Technical Conference. Fairbanks, AK. Society of American Foresters, Bethesda, MD.
- Jorgenson, M. T., J. E. Roth, M. Emers, W. Davis, S. F., Schlentner, and M. J. Macander. 2004. Landcover mapping for Bering Land Bridge National Preserve and Cape Krusenstern National Monument, northwestern Alaska. Natural Resource Technical Report NPS/ARCN/NRTR-2004/001. National Park Service, Fort Collins, CO. 129 pp.
- Raynolds, M. K., D. A. Walker, and H. A. Maier. 2006a. Alaska Arctic Tundra Vegetation Map. Scale 1:4,000,000. Conservation of Arctic Flora and Fauna Map No. 2. U.S. Fish & Wildlife Service, Anchorage, AK.
- Viereck, L. A., C. T. Dyrness, A. R. Batten, and K. J. Wenzlick. 1992. The Alaska vegetation classification. General Technical Report PNW-GTR286. USDA Forest Service, Pacific Northwest Research Station, Portland, OR. 278 pp.