The Alaska Vegetation Classification - Alaska Geobotany Center ...

C.2.a. Open Spruce-Paper Birch ForestFigure 3Mpen mixed forest of white spruce andpaper birch with a shrub layer of Alnus crispa anda herbaceous layer dominated by Calamagrostiscanadensis in south-central Alaska.Descrlptlon-These stands are comprised of paper birch and either white or blackspruce (fig. 36). Total tree cover is between 25 and 60 percent. The trees usually arefairly small, though trees in white spruce-paper birch stands may reach 15 meters(50 ft) in height and 20 centimeters (8 in) d.b.h. Alnus crispa and various speciesof willow may be important tall shrubs. Important understory species includeCalamagrostis canadensis and low shrubs such as Betula glandulosa, Spiraeabeauverdiana, Vaccinium uliginosum, V. vitis-idaea. and Ledum decumbens.Feathermosses such as Hylocomium splendens and Pleurozium schreberigenerallydominate the ground layer. In southwestern Alaska, open white spruce-paper birchstands have been reported from wet sites where the ground layer is a continuousthick mat of Sphagnumspp. Both foliose and fruticose lichens are important onsome sites.Distribution and site characteristics-Open spruce-paper birch forests occur onseveral upland sites in interior, south-central, southwestern, and northwestern Alaska.Many of these sites are relatively wet and poorly drained.Successional status-Successional relations of these communities are poorlyunderstood. Many of these communities appear to be stable and may be climax onsome sites. On other sites, with time, the birch is replaced by white or black spruce.Closely related types-These communities may be similar to open white spruce,open black spruce, and open paper birch types but are dominated by a mixture ofspruce and birch. They also are similar to closed spruce-paper birch communities,but with less than 60 percent cover, and to spruce-birch woodland, but with morethan 25 percent cover. They also may be similar to some of the dwarf tree scrubtypes.Photographs-Figure 36, this publication.Primary references-US. Department of Agriculture 1986, Viereck 1970bCommunities-Picea glauca-Betula papyrifera/Calamagrostis canadensis-Hylocomium splendens (Hettinger and Janz 1974, Viereck 1975). Piceaglauca-Betula papyrifera/Alnus crispa/Sphagnum spp. (Viereck 1975). Piceaglauca-Betula papyrifera/Salix planifolidSphagnum spp. (Viereck 1970b). PiceamarianaBetula papyrifera/Cladonia spp. (undescribed).