Circumpolar Arctic Vegetation Unit B1


Hierarchy of Geobotanical Vegetation Map Units (Walker DA 2002)

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map legend color for unit B1B1. Cryptogam, herb barren

Dry to wet barren landscapes with very sparse, very low-growing plant cover. Scattered herbs, lichens, mosses, and liverworts. Subzone A and B, some C at higher elevations.

Detailed Description

Dry to wet barren desert-like landscapes mainly in Subzone A and on some coarse-grained, often calcareous sediments in subzones B and C. Sparse (2-40%) horizontal plant cover, and very low vertical structure (generally <2 cm tall) with a single layer of plants where they occur. Dry herb barrens composed of few scattered vascular plants are present over much of the landscape. Snow-flush communities are often a conspicuous component, forming dark streaks on the otherwise barren lands, composed largely of bryophytes and cryptogamic crusts. In upland areas, vascular plant cover is generally very sparse (<2%), mainly scattered individual plants often in crevices between stones or small (<50 cm diameter) cryoturbated polygons. Sedges (Cyperaceae), dwarf shrubs, and peaty mires are normally absent.
Area: 225 x 1000 km2.

Representative Syntaxa

Communities of the classes: Thlaspietea rotundifolii Br.-Bl. et al. 1947, (e.g., Papaveretum dahliani Hofm. 1968), Salicetea herbaceae Br.-Bl. et al. 1947, (e.g., Phippsietum algidae-concinnae Nordh. 1943).

Dominant Plants

The most common vascular plants are cushion forbs, graminoids, lichens, mosses, liverworts, and cyanobacteria.

    1. Cushion forbs: Papaver dahlianum ssp. polare; Draba; Potentilla hyparcticaa; Saxifraga oppositifolian;
    2. Graminoid: Alopecurus alpinus; Deschampsia borealis/brevifolia; Poa abbreviata; Puccinellia angustata; Phippsia; Luzula nivalisa; Luzula confusaa;
    3. Lichen: Caloplaca; Lecanora; Ochrolechia; Pertusaria; Mycobilimbia; Collema; Thamnolia; Cetraria; Flavocetraria; Cetrariella; Stereocaulon;
    4. Moss: Racomitrium; Schistidium; Orthotheciumn; Ditrichumn; Distichiumn; Encalypta; Pohlia; Bryum; Polytrichum;
    5. Liverwort: Gymnomitrion; Cephaloziella;
    6. Cyanobacteria: Cyanobacteria;

a=acidic, n=non-acidic