Circumpolar Arctic Vegetation Map
Bioclimate Subzone B
Introduction - Subzone A - Subzone B - Subzone C - Subzone D - Subzone E
Subzone B. Mould Bay, Prince Patrick Island, Canada. Photo D.A. Walker.
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- Mean July temperature: 3-5 °C
- Summer warmth index: 6-9 °C
- Dominant plant growth form: Prostrate dwarf shrubs
- Number of vascular plant species in local flora: 50-100
Subzone B Description
Subzone B includes parts of the southern Queen Elizabeth Islands, the eastern fringe of Ellesmere Island, much of Peary Land in Greenland, the eastern portion of Svalbard, central Novaya Zemlya, the northern coast of the Taimyr Peninsula, and the New Siberian Islands. Because of its small size and weakly defined distinguishing characteristics, Subzone B could be characterized as a transition zone to Subzone C. Several treatments of Arctic zonation include Subzones B and C in a single subzone. For example, Yurtsev (1994) treats these two subzones as variants of his Arctic Tundra subzone, and Polunin (1951) places them both in the Middle Arctic. The mean July temperature at the southern boundary of Subzone B is approximately 5 °C. This subzone has scattered prostrate (creeping) dwarf shrubs on zonal soils. Erect shrubby vegetation is lacking. Mesic, low-elevation surfaces with fine-grained soils generally have open, patchy plant cover, generally with 5-50% cover of vascular plants although fine-grained sediments can have nearly complete cover of plants. Well-differentiated snowbed and riparian plant communities are lacking. Nonsorted circles, stripes, and ice-wedge polygons are common. Vascular plant vegetation is often confined to cracks and depressions in the polygonal network, and areas irrigated by runoff from snow patches. The dominant growth forms on mesic sites are prostrate dwarf shrubs (e.g.Dryas, Salix arctica, S. polaris), forbs (e.g., Draba, Saxifraga, Minuartia, Cerastium, and Papaver), graminoids, (e.g., Carex stans, Carex rupestris, Alopecurus alpinus, Deschampsia borealis, Luzula confusa), mosses and lichens. Rushes (Luzula) are also an important component of many mesic vegetation types. Sedges (Carex, Eriophorum) often are dominant in wet areas. This subzone has also been called the "prostrate dwarf-shrub subzone" (Walker et al. 2002) and the "Dryas octopetala zone" because of the importance of the prostrate woody species Dryas and Salix spp.