The Alaska Vegetation Classification - Alaska Geobotany Center ...

The shrub layer is dominated by some combination of Vaccinium alaskaense, V.ovalifolium, Menziesia ferruginea, and Gaultheria shallon. This layer is 1 to 1.5meters (3 to 5 ft) tall and is variable in its density; it provides from 20 to 80 percentcover. In some areas, a low shrub layer dominated by Empetrum nigrum is present.Common species in the herb layer include Lysichiton americanum, Cornuscanadensis, Coptis aspleniifolia, Tiarella trifoliata, Faufia crista-gall;, Carex spp.,Blechnum spicant, Athyrium filix-femina, and Gymnocarpiurn dryopteris. Total herbcover ranges from 40 to 80 percent.Distribution and site characterlstics-These communities are common in southeastAlaska on nearly level sites, hilltops, benches, lowlands, and valley bottoms, aswell as gentle slopes. Soils are wet and poorly drained; they are either organic orhave thick organic surface horizons.Successional status-These communities are stable and slow to change. Becausethey are rarely disturbed, secondary succession patterns leading to these communitiesare unknown. Tree growth rate on these sites is low; therefore, recovery fromsevere disturbance undoubtedly would be slow.Closely related types-Some of these communities resemble open mountain hemlockor open western hemlock-Sitka spruce stands, but they have a greater diversityof overstory tree species and are less strongly dominated by mountain hemlock orwestern hemlock and Sitka spruce. At the other extreme, some stands may resemblelodgepole pine woodlands but have greater overstory cover (greater than 25 percent),a greater diversity of overstory species, and a greatly reduced dominance of lodgepolepine. Open mixed conifer forest also may resemble certain shrubby bog typesbut is differentiated by greater cover of trees.Photographs-Figure 14, this publication.Primary reference-Martin and others 1985.Communities-Tsuga heterophylla-Chamaecyparis nootkatensis-Tsuga mertensianuPicea sitchensis/Vaccinium spp./Lysichiton americanum (Martin and others 1985).Tsuga heterophylla-Chamaecyparis nootkatensis-Tsuga mertensiana-Picea sitchensis/Lysichiton americanum-Athyrium filix-femina (Martin and others 1985). Chamaecyparisnootkatensis-Tsuga mertensiana-Tsuga heterophylla-Picea sitchensis-Pinus contortdVaccinium spp./Fauria crista-galli (Marlin and others 1985).I.A.2.e.Open White Spruce ForestDescrlption-These stands are dominated by white spruce with total tree cover inthe range of 25 to 60 percent (fig. 15). Trees are relatively small but variable in size.The largest trees are typically about 16 meters (50 ft) in height and 30 centimeters(12 in) d.b.h. Black spruce, paper birch, and aspen may be present but do not providemuch cover. A shrub layer dominated by Betula glandulosa 1 to 2 meters (3 to 6 ft)tall is usually well developed. Alder (Alnus crispa or A. sinuata) and willows (primarilySalix planifolia and S. lanata) are common locally, especially on wetter sites. Lowshrubs such as Shepherdia canadensis and Rosa acicularis may be present,particularly on lowland sites. Common herbs include Linnaea borealis, Equisetumspp., and Calamagrostis canadensis. Beneath the tall shrubs is a nearly continuouslayer of feathermosses, primarily Pleurozium schreberi and Hylocomium splendens.