Circumpolar Arctic Vegetation Unit B4


Hierarchy of Geobotanical Vegetation Map Units (Walker DA 2002)

Brooks Range, Alaska. Photo D.A. Walker.
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map legend color for unit B4B4. Carbonate mountain complex

Mountain vegetation on carbonate bedrock. The variety and size of plants decrease with elevation and latitude. Hatching color and code indicate the bioclimate subzone at the mountain base. B4b through B4e indicate subzones B through E; B4n indicates carbonate nunatak areas.

Detailed Description

Dry calcareous tundra complexes on mountains and plateaus with limestone or dolomite bedrock. Vegetation changes with elevation in the mountains, forming elevation belts whose vegetation is physiognomically similar to that of bioclimate subzones with comparable summer climate (see the elevation belt). The color of the polygon hatch pattern denotes the bioclimate subzone at the base of the mountains. For example, B4b occurs in Subzone B, B4c in Subzone C, etc. B4n denotes nunatak areas, with many carbonate mountain peaks surrounded by glaciers. Mesic zonal microsites are relatively uncommon. More common are plant communities growing on wind-swept, rocky ridges, screes, and dry fell-fields, alternating with snowbed plant communities.
Area: 136 x 1000 km2.

Representative Syntaxa

Belt a, Thlaspietea rotundifolii vegetation, e.g., Papaveretum dahliani Hofm. 1968; Belt b, Carici-Dryadetum integrifoliae Dan. 1982; Belt c, Carici- Dryadetum integrifoliae Dan. 1982; Belt d, Dryado integrifoliae-Caricetum bigelowii Walk. et al. 1994 (all Carici-Kobresietea); Belt e, cf. Anemono-Salicetum richardsonii Schickh. et al. 2002 (most of Northern America).

Dominant Plants

Saxicolous lichens cover the rock surfaces. Trees and shrubs, the grass Hierochloe alpina, and terricolous lichens, grow between the bedrock outcrops.

a=acidic, n=non-acidic