Alaska Arctic Plant Communities

24. Dryas integrifolia-Carex rupestris

Photo A. Dryas integrifolia-Carex rupestris community on pingos at Prudhoe Bay, Alaska. Walker slide 74-12-8. Photo D.A. Walker.
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Photo B. Detail showing lichen-covered hummocks of Dryas integrifolia-Carex rupestris community. Walker slide 74-12-9. Photo D.A. Walker.
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Photo C. Dryas integrifolia-Carex rupestris-Lecanora epibryon community on pingo at Prudhoe Bay, Alaska. Walker (1985), Fig. 8. Photo D.A. Walker.
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Photo D. Dry tundra on ridge near the Kaktakturuk River, Arctic National Wildlife Refuge. Walker slide 81-20-19. Photo D.A. Walker.
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Bioclimate Subzone: D

Floristic Subprovince: Northern Alaska

Substrate Chemistry: Nonacidic

Position along mesotopographic gradient: Dry exposed site

Summary of Habitat: Dry nonacidic tundra on gravels in subzones C and D

Described from: Prudhoe Bay (Walker 1985, Walker 1990)

 

Common plant functional types and species:

Prostrate dwarf shrubs: Dryas integrifolia; Salix reticulata;

Lichen: Lecanora epibryon; Pertusaria spp.; Ochrolechia frigida; Thamnolia subuliformis; Flavocetraria cucullata; Physconia muscigena; Flavocetraria nivalis; Hypogymnia subobscura; Cetraria islandica; Dactylina arctica; Cladonia pocillum; Bryocaulon divergens;

Sedge: Carex rupestris;

Forb: Oxytropis nigrescens; Saxifraga oppositifolia; Draba cinerea; Leucanthemum integrifolium; Papaver lapponicum; Lesquerella arctica; Pedicularis lanata; Pedicularis capitata; Silene acaulis; Minuartia arctica;

Moss: Encalypta spp.; Ditrichum flexicaule; Distichium inclinatum; Distichium capillaceum; Tortula ruralis; Ctenidium procerrimum; Sanionia uncinatus;

 

General Comments:

• This type occurs mainly on dry wind-exposed nonacidic gravelly sites. The plant canopy consists of a discontinuous mat of Dryas integrifolia, an abundance of lichens, a few cushion forbs such as Oxytropis nigrescens and Saxifraga oppositifolia and several other erect forbs. A high percentage of the soil is unvegetated or covered in white crustose lichens (e.g., Lecanora epibryon). The sedge Carex rupestris is constant.
• The community Dryas integrifolia-Carex rupestris embraces all of the diversity within the non-riparian nonacidic Dryas integrifolia group of communities. It excludes the Dryas communities on river terraces that have higher diversity of forbs and erect shrubs (Community 34 and Community 83), and the communities on cryoturbated moister soils that lack Carex rupestris (Community 8). Similar Dryas communities occur within bioclimate subzones C and D of the Canadian archipelago (e.g., Dryas integrifolia-Carex rupestris comm. described from several studies in Arctic Canada and Greenland (e.g., Vonlanthen et al. 2008 (10 relevés); Schweingruber 1997; Thannheiser 1988; Thannheiser and Geesink 1990; Gonzalez et al. 2000, Victoria Island, Mount Pelly, V-CB-01, 05; Carici-Dryadetum integrifoliae (Daniëls 1982) described from Greenland). It is a nonacidic counterpart to Luzula confusa-Sphaerophorus globosus which occurs on dry acidic sites (Community 13).
• M.D. Walker (1990) sampled 77 stands on exposed north and ENE slopes of 41 pingos of the central Arctic coastal plain. 72 of these were nonacidic. Within the broad nonacidic group that she called Dryas integrifolia-Lecanora epibryon, she identified 3 distinct stand types: (1) Stand Type Cerastium beeringianum-Minuartia rubellum (5 relevés) occurred in very exposed sites near the coast; (2) Stand Type Dryas integrifolia-Oxytropis nigrescens (37 relevés) was the most common type — occurring mostly on north-facing exposed sites and best drained sites in and around Prudhoe Bay; (3) Stand Type Dryas integrifolia-Astragalus umbellatus (31 relevés) occurred on somewhat warmer less exposed sites with moister soils and higher diversity of herbs (e.g., Astragalus umbellatus, Papaver macounii, Parrya nudicaulis, Oxytropis jordalii, Carex scirpoidea).

 

Other names from the Alaska literature:

• Stand Type B1, Dry Dryas integrifolia, Carex rupestris, Oxytropis nigrescens, Lecanora epibryon dwarf shrub, crustose lichen tundra, 6 relevés, Prudhoe Bay, D.A. Walker (1985).
• Stand Type Dryas integrifolia-Oxytropis nigrescens, 37 relevés, Central Arctic Coastal Plain pingos, M.D. Walker (1990).

 

Braun-Blanquet Name:

• The Dryas integrifolia-Carex rupestris community is more or less equivalent to Association Carici-Dryadetum integrifoliae (Daniëls 1982) described from Greenland. The Oxtropis nigrescens subtype would likely be defined as a subassociation.