The Alaska Vegetation Classification - Alaska Geobotany Center ...

Closely related types-Some dry fescue communities are similar to some dry€/ymus innovatus communities, and others are similar to mesic bluejoint communities;the dry fescue communities have a greater cover of fescue. With increasingshrubs or herbs, dry fescue communities grade into midgrass-shrub or midgrass-herbcommunities, respectively. Shrubs are inconspicuous in dry fescue communities andforbs are not dominant.Photographs-Figure 59, this publication.Primary references-Hanson 1951, Viereck 1962.Communities-Festuca altaica (Hanson 1951, 1953; Pegau 1972; Viereck 1962).Fesfuca a/faica-Ca/amagrosfis canadensis (Hanson 1951).1II.A. 1.c. Mldgrass-ShrubDescription-These communities are commonly dominated by medium-heightgrasses such as Fesfuca altaica, Calamagrostis purpurascens, Agropyron spicafum,Poa spp., and Bromus pumpellianus (fig. 60). Shrubs are conspicuous but provideless than 25 percent cover. The shrubs occasionally provide more cover than thegrass but still less than 25 percent. Common shrubs on alpine and subalpine slopesinclude ericaceous shrubs, such as Vacciniurn vifis-idaea and Empetrum nigrum, andlow willows. Sagebrush (Arfeemisia spp., especially Artemisia frigida) is the commonshrub on dry slopes. Feathermosses may be commn (especially on alpine sites) orabsent. Lichens often are common but may be absent. Total canopy cover is open(dry slope communities are almost always open) or closed. The grasses generallyare 30 to 70 centimeters (12 to 30 in) tall, the shrubs 10 to 30 centimeters (8 to12 in) tall.Distribution and site characteristics-Midgrass-shrub communities occur on dryslopes at low elevations and on mesic to dry slopes and plateaus in alpine and subalpinesettings. They generally are restricted to interior and south-central Alaska andthe surrounding mountain ranges.Soils are typically silt loams, often with abundant intermixed gravel or rock fragmentsLow-elevation dry slope soils are generally slightly acid to moderately basic (pH 6 to8). Alpine soils are usually acid (pH 5 to 6). Permafrost has not been reported butmay be present under some alpine stands.Successlonal status-These communities appear to be fairly stable. The Fesfucaalfaica-ericaceous shrub types may have developed from dry fescue communitiesand may be evolving toward open ericaceous shrub scrub. The dry slope typesappear lo be stable and generally occupy slopes too steep and dry for woody plantsother than sagebrush.Closely related types-The Fesfuca altaica-shrub types are similar to dry fescuecommunities but have a conspicuous shrub element. The dry slope grass-sagebrushtypes are similar to sagebrush-juniper open low shrub scrub, but juniper is lacking,grasses are dominant, and sagebrush has less than 25 percent cover.Photographs-Figure 60, this publication.Primary references-Hanson 1951, Scott 1974a.