Circumpolar Arctic Bioclimate Subzone E

 

Subzone E. Low-shrub tundra (alder savannah), north of Kigluaik Mountains, Seward Peninsula, Alaska. Photo D.A. Walker.
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Circumpolar Arctic Bioclimate Subzone E
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Subzone E. Tussock-sedge, dwarf-shrub, moss tundra; Community No. 41, Arctic Foothills, near Oumalik, Alaska. Photo: D.A. Walker.
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Subzone E Description

Subzone E is the warmest part of the Arctic Tundra Zone with mean July temperatures of 9-12 °C. In Subzone E, the zonal vegetation is dominated by hypoarctic low shrubs that are often >40 cm tall (e.g., Betula nana, B. exilis, B. glandulosa, Salix glauca, S. phylicifolia, S. planifolia, S. richardsonii, Alnus spp.). True shrub tundra with dense canopies of birch, willows, and sometimes alder (Alnus) occur in many areas. Birch or willow thickets 80-200 cm tall occur on zonal sites in some moister areas such as west Siberia and northwest Alaska. In more continental areas and areas with less snow cover, the shrubs are shorter and form a more open canopy. Tussock tundra is common in northern Alaska and eastern Siberia and has taller shrubs and more cover of shrub than in Subzone D (Alexandrova 1980). Low and tall (>2 m) shrubs are abundant in most watercourses. In some areas, toward the southern part of Subzone E that are continuous with the boreal forest, patches of open forest penetrate into this subzone along riparian corridors. These woodlands consist of a variety of species of spruce (Picea), pine (Pinus), cottonwood (Populus), and larch (Larix) and tree birches (Betula). Peat plateaus (palsas) up to 1.5 m tall are common in lowland areas. This subzone has also been called the "low-shrub subzone" and could be called the "Alnus zone".