OLD - Dwarf-shrub Tundra

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Dwarf-shrub tundra can be of prostrate growth form, barely above the arctic ground surface, or, in southern or oceanic areas, up to 40 cm tall. The vegetation is dominated by dwarf and low shrubs – graminoids can be present but are a minor component.

The erect dwarf-shrub tundra can be dominated by species such as scrub birch (Betula nana), northern Labrador-tea (Ledum palustre spp. decumbens), lingonberry (Vaccinium vitis-idaea), bog blueberry (Vaccinium uliginosum), crowberrys (Empetrum spp.), or greyleaf willow (Salix glauca).

Four-angle mountain-heather (Cassiope tetragona) dominates acidic soils in much of high and mid arctic. Other dwarf-shrubs in this vegetation are polar willow (Salix polaris) and arctic willow (Salix arctica). Consistent forbs are mountain sorrel (Oxyria digyna), alpine bistort (Bistorta vivipara), and moss campion (Silene acaulis).

A prostrate dwarf-shrub tundra is common in much of the mid to high arctic. Vegetation cover varies from 20-80%, including mosses and lichens, with various willows dominating the vascular plant cover including: polar willow (Salix polaris), least willow (Salix rotundifolia) and arctic willow (Salix arctica). Mountain-avens (Dryas spp.) dominates in non-acidic soils. Associated graminoids are: curly sedge (Carex rupestris) and tall cottongrass (Eriophorum angustifolium), and in acidic soils, northern woodrush (Luzula confusa) and arctic wood-rush (Luzula nivalis). Some saxifrages may also be found, e.g., yellow marsh saxifrage (Salix hirculus), purple mountain saxifrage (Saxifraga oppostitifolia), or

tufted saxifrage (Saxifraga caespitosa).

Mosses of the dwarf-shrub tundra include step moss (Hylocomium splendens), mountain groove-moss (Aulacomnium turgidum), sickle moss (Sanionia uncinata), heron's bill mosses (Dicranum spp.), hoary rock-moss (Racomitrium lanuginosum) and golden fuzzy fen moss (Tomenthypnum nitens). Common lichens are foam lichens (Stereocaulon spp.), paperdoll lichens (Cetraria spp.), clad lichens (Cladonia spp.), whiteworm lichens (Thamnolia spp.), freckle pelt (Peltigera aphthosa), arctic tumbleweed lichen (Masonhalea richardsonii) and owl lichens (Solorina spp.).