The Alaska Vegetation Classification - Alaska Geobotany Center ...

Primary reference-Hjeljord 1971.Communities-Carex macrocbaeta-Geranium erianfbum-Erigeron peregrinus-Lupinus nootkatensis (Hjeljord 1971).lll.A.2.g. Mesic Grass-Herb Meadow TundraDescription-Mesic grass-herb meadow tundra is dominated by grasses (commonlyArcragrosfis latifolia, Bromus pumpellianus, Trisetum spicatum, and Poa spp.) andforbs (including Oxyria digyna, Petasires frigidus, and Saxifraga spp., among manyothers). Canopy height is usually under 50 centimeters (20 in). Plant cover is variable(open to closed).Distribution and site characteristics-These communities are restricted to occasionalsmall stands on various mesic sites throughout the arctic part of the State,including streambanks, sheltered pockets on slopes, and high-center polygons. Soilsare relatively thin and well drained. Permafrost is probably present beneath all standsbut may be under a thick active layer.Successional status-Successional relations of mesic grass-herb meadow tundraare unknown, but it seems likely that the successional trend would be for sedges orlow shrubs to gradually invade and gain dominance on at least some of these sites.Closely related types-These stands are similar to mesic sedge-herb tundra buthave more grasses and few sedges. Some stands may be similar to some mesicmixed herb communities but have more grass cover.Primary referenceKoranda 1960.Communities-Bromus pumpellianus-Trisetum spicafum-Bupleurum triradiatum(Koranda 1960). Luzula confusa-Poa arctica-Pefasites frigidus (Wiggins 1951).lll.A.2.h. Sedge-Wiiiow TundraDescriptionSedge-willow tundra is dominated by sedges (commonly Carexaquatilis, C. bigelowii, or C. microchaeta) and has a conspicuous willow component,though total shrub cover is less than 25 percent. Common willows include Salixplanifolia, S. lanata, S. fuscescens, S. reticdata, S. phlebophylla, S. rofundifolia,S. ovalilolia, and S. arcfica. Other shrubs may be present but are usually minorcomponents of the vegetation. Dryas integrifolia may be common at some sites.Mosses, especially species of Aulacomnium, Tomenfhypnum, Hylocomium, andPolytrichum, are common and may form a continuous mat. Sphagnumspp. aregenerally rare, but are abundant at some sites. Lichens are relatively scarce butcommon locally. Canopy height is about 15 to 50 centimeters (6 to 20 in); coverusually is complete.Distribution and site characteristics-Sedge-wiiiow tundra is found on wet tomesic sites on flood plains, benches, plateaus, low-center polygons, drained lakebasins, and north slopes, primarily in the Arctic but also in alpine areas. Frost scarsare abundant in some communities. Carex aquatilis dominates the wetter sites; othersedges dominate on the more mesic sites. Acid to circumneutral tundra soils (poorlydrained, fine-textured mineral soils with a surface organic mat of variable thickness)commonly form the substrate, with permafrost at about 35 to 150 centimeters (14 to60 in) (the deeper extremes from Alaska Range alpine sites). Low microrelief ridges,hummocks, or solifluction lobes often are present, and the shrubs often areconcentrated on these features.173