Alaska Arctic Plant Communities

2. Carex aquatilis-Saxifraga cernua

Photo A. Community type Carex aquatilis-Saxifrage cernua in a moist meadow near the NOAA Barrow Observatory. Elias et al. 1996, Fig. 8a. Photo D.A. Walker.
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Photo B. Close up showing the sedge Carex aquatilis and scattered forbs. Larger green leaves are Petasites frigidus. Elias et al. 1996, Fig. 8b. Photo D.A. Walker.
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Bioclimate Subzone: C

Floristic Subprovince: Northern Alaska

Substrate Chemistry: Acidic

Position along mesotopographic gradient: Moist site

Summary of Habitat: Moist acidic coastal tundra in subzone C

Described from: Barrow (Webber 1978)

 

Common plant functional types and species:

Sedge: Carex aquatilis; Eriophorum angustifolium ssp. triste;

Grass: Poa arctica; Dupontia fisheri; Alopecurus alpinus;

Rush: Luzula arctica;

Prostrate dwarf shrubs: Salix rotundifolia; Salix pulchra;

Forb: Saxifraga cernua; Saxifraga foliolosa; Saxifraga hieraciifolia; Saxifraga hirculus; Cardamine pratensis; Petasites frigidus; Stellaria spp.; Ranunculus nivalis;

Moss: Oncophorus wahlenbergii; Dicranum elongatum; Sarmenthypnum sarmentosum; Aulacomnium turgidum; Mnium sp.;

Lichen: Sphaerophorus globosus; Dactylina arctica; Cladonia spp.; Cetraria spp.; Flavocetraria cucullata; Thamnolia subuliformis;

 

General Comments:

• This is a common type in mesic acidic meadows and flat-centered polygons in coastal tundra areas of subzone C (photos a and b). It is dominated by graminoids (Carex aquatilis, Eriophorum angustifolium, Poa arctica, Dupontia fisheri, Luzula arctica), prostrate dwarf shrubs (Salix rotundifolia, S. pulchra), mosses and a variety of small forbs (especially Saxifraga cernua and S. foliolosa), and has the highest lichen diversity of any of the types studied by Webber (1978). It corresponds to the Nodum III (Mesic Carex aquatilis-Poa arctica) at Barrow (Webber 1978) and is the most extensive type within the International Biological Program (IBP) Tundra Biome study site at Barrow, covering about 41% of the area (Walker and Webber 1974). A more or less equivalent type has been described using the Braun-Blanquet protocols at Prudhoe Bay: Salici rotundifoliae-Caricetum aquatilis (Kade et al. 2005). It is common but is not a separable map unit at the scale of the Alaska Arctic Vegetation Map (Raynolds et al. 2006). Somewhat moister habitats can have abundant Dupontia fisheri and few lichens (Nodum IV, Moist Carex aquatilis-Oncophorus wahlenbergii meadow, (Webber 1978)). A nonacidic equivalent has been described for Barter Island (See Community 9) (Elias et al. 1996).

 

Other names from the Alaska literature:

• Nodum III, Mesic Carex aquatilis-Poa arctica meadow, 11 study plots; Nodum IV, Moist Carex aquatilis-Oncophorus wahlenbergii meadow, 6 study plots, Barrow, Webber (1978).
• Stand Type 6 (Carex aquatilis, Dactylina arctica, Polytrichum juniperinum, 5 study plots; and in somewhat moister situations, Type 7, Carex aquatilis, Dupontia fisheri, Petasites frigidus, Peltigera aphthosa, Minum sp., 5 study plots, Walker (1977).
• Saxifraga cernua-Carex aquatilis, Barrow, 10 relevés, Elias et al. (1996).
• Stand Type U12, Moist Carex aquatilis, Salix planifolia ssp. pulchra, Campylium stellatum sedge, dwarf shrub tundra, Prudhoe Bay, 2 study plots (1303, 1311), Walker (1985).
• Salici rotundifoliae-Caricetum aquatilis, Prudhoe Bay, 5 relevés, (Kade et al. 2005)
• Included within III.A.2.e., Mesic sedge-grass meadow tundra, Alaska Vegetation Classification, (Viereck et al. 1992).

 

Braun-Blanquet Name:

• Salici rotundifoliae-Caricetum aquatilis (Kade et al. 2005).