The Alaska Vegetation Classification - Alaska Geobotany Center ...

Closely related typesopen low alder shrub is similar to open tall alder shrub, butthe general level of the canopy is lower than 1.5 meters (5 11). These communitiesalso are similar to open low alder-willow communities but have little or no willowcover. Some are similar to shrub-tussock tundra but have more alder and few, if any,tussocks.Primary references-Bliss and Cantlon 1957, Drew and Shanks 1965.CommunitlesAlnus crispdVaccinium uliginosum-Ledum decumbensBe1ula nana-Carex bigelowii/Hyocomium splendens-Aulacomnium palusfre (Bliss and Cantlon1957). Alnus crispdBefula glandulosa-Ledum decumbens/Sphagnum spp. (Drew andShanks 1965, Ritchie and others 1981).ll.C.2.m. SagebrushJuniperDescription-Although these communities are known to exist on steep south-facingbluffs in interior and south-central Alaska, none has been described.ll.C.2.n. Sagebrvsh-GrassDescription-These communities have 25 to 75 percent cover of shmbs tallerthan 20 centimeters (8 in), which is primarily sagebrush (fig. 50). Shrubs taller than1.5 meters (5 ft) generally are absent or at most contribute less than 25 percentcover. Tree canopy cover, primarily aspen, is less than 10 percent. Common sagebrushesinclude Artemisia frigida and A. alaskana. Common associated grassesinclude Calamagrosfis purpurascens, Agropyron spicafum, Bromus pumpellianus,and Festuca alfaica. Other common species include Potenfilh pennsylvanica andPoa glauca. Mosses are scarce and lichens are scattered.Distribution and site characteristics-Sagebrush-grass communities occur locallyon steep south-facing bluffs primarily along major river systems in interior and southcentralAlaska. The substrate vanes from silt loams to rocky silts and is extremelysteep, unstable, and dry. Plant cover is discontinuous and much bare ground isexposed. Soil reaction is generally circumneutral, pH 6-8. Permafrost is absent.Successional status-These communities are stable in the specialized localitiesthey exist in. They sometimes share the bluffs with open stands of stunted aspen,which presumably are on slightly moister microsites.Figure W p e n low sagebrushgrassshrub of Alfemisia frigida,Bromus pumpelkanus, Calamagrostispurpurascens, and Agropyron spicatumon a south-facing river bluff in interiorAlaska.144