The Alaska Vegetation Classification - Alaska Geobotany Center ...

Figure 60-Midgrass-shrub stand of thegrasses Calamagrostis purpurascens, Bromuspumpellianus, and Elymus innovatus, shrubsof Artemisia frigida, and the herbs Pulsatillapatens, Antenarria rosea. Silene menziesii,and Arabis holboelliion a south-facing bluffin interior Alaska.Communities-Festuca alfaica-Salix lanafa-Artemisia arcfica (Scott 1974a).Calamagrostis purpurascens-Artemisia frigida (Batten and others 1979, Hanson1951). Fesfuca altaica-Empetrum nigrum-Salix reficulafa (Scott 1974a). Agropyronspicafum-Artemisia frigida (Batten and others 1979, Hanson 1951). Fesfucaalfaica-Calamagrosfis canadensis-Empetrum nigrum (Bos 1967). Poaglauca-Artemisia frigida-Calamagrostispurpurascens (Hanson 1951).III.A.1.d. Midgrass-HerbDescription-These communities are dominated by middle-height grasses andbroad-leaved herbs (fig. 61). A few communities have been included here that aredominated entirely by grasses, or grasses and sedges are codominant. Commondominant grasses include Fesfuca alfaica. F. rubra, Deschampsia beringensis,Poa eminens, and Agropyron subsecundum. Herbs reported as codominantinclude Anemone narcissiflora, Lupinus arcticus, Aconitum delphinifolium, Mertensiapaniculafa, Cornus canadensis, Geranium erianfhum, Potentilla egedii, and Achilleaborealis. Woody plants are rare or absent. Nonsphagnaceous mosses (especiallyfeathermosses) are common in many of these communities. Plant cover is usuallyhigh.Distribution and site characteristics-Midgrass-herb communities are found onvarious mesic sites, including alpine and subalpine meadows, streambanks, lowlandmeadows, and coastal slough levees. Coastal slough levee variants are foundthroughout the State, but the others are restricted lo the Aleutian Islands and interior,south-central, and southeastern Alaska. On coastal slough levees, the substrate isusually barely modified, tidally deposited silt. Other midgrass-herb communitiesgenerally occur on well-developed, well-drained silt loams or occasionally on sands.Soil pH is circumneutral to acid (usually 5.4 to 7.4), but values as low as 4.6 havebeen reported. The alpine sites tend to be acidic and the low-elevation sites circumneutral.Permafrost generally is absent but has been reported at depths of about1 meter (3 ft) from sites in the Alaska Range. Associated species characteristic ofcoastal slough levees are Festuca rubra, Poa eminens, and Pofenfilla egedii.Agropyron spp. and Deschampsia beringensis are restricted to low elevations;Festuca altaica and most of the herbs occur over a broad elevational range.163