The Alaska Vegetation Classification - Alaska Geobotany Center ...

Figure 24-Closed broadleaf forest of redalder in southeastern Alaska.Closely related types-Red aider forests differ from tall alder scrub by beingcomposed of a taller and more treelike alder. They also are similar to open Sitkaspruce forests but have less spruce and more alder.Photographs-Figure 24, this publicationPrimary referencede1 Moral and Watson 1978, Viereck and Little 1972.Communities-Alnus rubra (del Moral and Watson 1978)LA. 1.6. Closed Black Cottonwood ForestDescription-These communities are dominated by black cottonwood (Populustrichocarpa), which commonly grow 24 to 30 meters (80 to 100 11) tall and reachdiameters of up to 1 meter (3 ft). Young stands tend to have continuous tree coverwith sparse understories. As the stands age, openings in the canopy allow the understoryto develop more fully. Common shrubs include Rosa acicularis. Viburnumedule, and Oplopanax horridus. Calamagrostis canadensis and Equisetum spp. arethe dominant species of the herb layer.Distribution and site characteristics-Black cottonwood communities are commonon moist, well-drained sites on flood plains in south-central and southeastern Alaska.Successional status-These are seral communities in the primary succession ofstream terraces and flood plains that are intermediate between various early seralshrub communities on the one hand, and birch and spruce forest communities on theother.85