Circumpolar Arctic Bioclimate Subzone C

 

Subzone C. Green Cabin, Banks Island, Canada. Photo D.A. Walker.
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Circumpolar Arctic Bioclimate Subzone C
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Subzone C Description

Subzone C includes northern Banks Island, northern Victoria Island, Devon Island, Prince of Wales Island, Somerset Island, northern Baffin Island, most of Ellesmere Island, Axel Heiberg Islands, the west coast of Greenland, and inner fiord regions of northeast Greenland, southern Novaya Zemlya, some coastal areas of Yakutia and Chukotka, and the northernmost coast of Alaska (Yurtsev 1994). The mean July temperature at the southern boundary of Subzone C is about 7 °C. Mesic zonal surfaces in this subzone have more luxuriant plant growth than that in Subzone B. Zonal sites are generally well vegetated, but vascular plant cover is still open, and interrupted by frost scars and other periglacial features. The main features distinguishing Subzone C from Subzone B is the presence of the hemi-prostrate shrub Cassiope tetragona and well-differentiated plant communities in mires, snowbeds and creek sides. Cassiope covers large areas on mesic sites in areas with acidic parent material, such as on Svalbard, Baffin Island, and interior portions of Greenland. However, Cassiope is lacking on mesic alkaline surfaces in the western Canadian Islands. In these areas, Cassiope is generally confined to snow accumulation areas. Subzone C has much greater species diversity than Subzone B. Sedges, such as Kobresia myosuroides, Carex bigelowii, and Carex rupestris, are common on upland surfaces, and numerous forbs, such as members of the Fabaceae (e.g., Oxytropis, Astragalus) are important in nonacidic regions. Communities in intrazonal habitats (snowbeds, and creek sides) are well developed. Wetland communities are much better developed than in Subzone B. Creek sides have distinctive Epilobium latifolium communities. This subzone has also been called the "hemi-prostrate dwarf-shrub" subzone (Walker et al. 2002) and the "Cassiope tetragona zone" because of the importance of Cassiope in many areas.