Physiognomy and Structure: This macrogroup is defined by treeless, low-stature vegetation that is mostly graminoid-, dwarf-shrub-or low shrub-dominated but can include sparse, lichen-dominated alpine tundra, mesic herbaceous meadows.

Floristics: This macrogroup includes the Northern Alaska and Beringian Alaska floristic subprovinces. Differing histories of connectivity due to intercontinental bridging and glaciation as well as geographic barriers such as mountain ranges contribute to differing regional floristics within the range of this macrogroup. Tundra vegetation types range in ecoregion from alpine to arctic and in physiognomy from graminoid to shrub. Sparse cover in the high alpine is characterized by crustose lichens of the Umbilicaria genus in combination with the forbs Potentilla elegans and Smelowskia calycina var. porsildii and the prostrate dwarf-shrub Loiseleuria procumbens. Dwarf-shrub tundra is grouped by Dryas, ericaceous or willow species dominance. Dryas dwarf-shrub tundra occurs in dry, windswept areas with little retention of snow cover and is characterized by Dryas octopetala in the Brooks Range and foothills (bioclimatic subzone E), which transitions to Dryas integrifolia on Alaska''s Arctic Coastal Plain (bioclimatic subzones C and D). Dwarf willow shrub tundra occurs in small patches on exposed sites across the geographic range of the macrogroup and is characterized by Salix reticulata, Salix polaris, Salix rotundifolia, and Salix phlebophylla. Ericaceous dwarf-shrub tundra is common in more protected, mesic sites where snow cover is retained. The group is characterized by the ericaceous shrubs Ledum palustre ssp. decumbens, Cassiope tetragona, and Vaccinium vitis-idaea. Low-shrub tundra may be dominated by willows such as Salix richardsonii, Salix pulchra, and Salix glauca or Betula nana. Both types commonly occur on mesic to moist sideslopes and ridges and high-centered polygonal tundra. Variations of low-shrub tundra include water tracks (described as a proposed type concept, ~North American Arctic & Subarctic Wet Shrubland Group (G830)$$ in M870) and moist tundra, which is differentiated from low-shrub tundra by lower cover of prostrate shrubs and from tussock tundra by the absence of tussocks. Mesic herbaceous tundra is an uncommon type occupying small patches in areas of late-lying snow and streamsides. Characteristic species include the forbs Chamerion angustifolium, Lupinus arcticus, Polemonium boreale, and Valeriana capitata and the grasses Calamagrostis stricta, Arctagrostis latifolia, Deschampsia cespitosa, and Poa arctica. Tussock tundra is characterized by high abundance of the tussock-forming sedges Eriophorum vaginatum and/or Carex bigelowii often in combination with dwarf- and low shrubs. Polygon tundra is a mosaic of dwarf-shrub, low shrub and wet sedge tundra (described under M870), with shrub and tussock tundra types occupying mesotopographic highs such as the centers of high-centered polygons and the ridges of low-centered polygons, and wet sedge tundra occupying the bounding troughs.

Dynamics:  In areas of fine-grained, ice-rich sediment, thermoerosional processes such as permafrost degradation and aggregation, cryoturbation, and solifluction are active. Changes in exposure or drainage are likely drivers of successional change for dwarf-shrub and tussock tundra types. While infrequent, wildland fire may have extensive and severe impact on tundra ecosystems. Fire may revert shrub types to a graminoid-dominated system, whereas shrubs may assume dominance with amelioration of climate or site condition.