The Alaska Vegetation Classification - Alaska Geobotany Center ...

Dlstrlbutlon and Site characteristics-Closed tall shrub swamps are common ininterior, south-central, and southeastern Alaska on marshy streambanks, poorlydrained forest openings, bog edges, seepage areas below bluffs, and other poorlydrained sites with relatively nutrient-rich water. The substrate is usually hummocky,with water in the depressions throughout all or much of the growing season. Thewater is not stagnant but moves slowly through the system. The substrate generallyconsists of fine-textured mineral soil, sometimes with substantial quantities of intermixed,well-decomposed organic matter and sometimes with a thin surlicial peatlayer. Soil reaction is normally circumneutral to acid but usually above pH 5.0.Successional status-These communities probably represent topoedaphic climaxesin many cases and will persist as long as the hydrologic conditions causing seepageand flooding persist.Closely related types-Closed tall shrub swamps resemble closed tall alder, willow,and alder-willow stands but are much wetter. Alnus tenuifolia is a common (but notuniversal) dominant of shrub swamps and rarely dominates scrub communities onmesic sites. Closed tall shrub swamps are also similar to open tall shrub swamps buthave 75 percent or more of tall shrub cover.Photographs-Crow 1968, figure 9; Hogan and Tande 1983, plate 9; Tande 1983,plate 19.Primary references-Batten and others 1978, Crow 1968, Hogan and Tande 1983,Ritchie and others 1981, Tande 1983, Webber and others 1978.Communities-Salix planifolia/Calamagrostis canadensis/Sphagnum spp. (Webberand others 1978). Alnus tenuifolia/Calamagrostis canadensis (Batten and others1978, Hanson 1953, Quimby 1972). Alnus tenuifolkVCarex aquatilis (Ritchie andothers 1981). Betula papyrifera-Alnus tenuifoli~Calamagrostis canadensis (Hoganand Tande 1983, McCormick and Pichon 1978, Ritchie and others 1981, Tande1983). Alms sinuata/Calamagrostis canadensis (Crow 1968, Scheierl and Meyer1977).11.8.2. Open Tall ScrubThis includes communities of tall (1.5 meters [5 it] or taller) shrubs with open (25 to75 percent tall shrub cover) canopies. Low shrubs may be abundant or absent. Tallshrub cover may be as low as 2 percent if mosses, herbs, and low shrubs are absentll.B.2.a. Open Tall Willow ShrubDescrlptlon-These are communities where the overstory canopy is dominatedby willows about 1.5 meters (5 It) high or higher, with a tall shrub cover of 25 to75 percent (fig. 41). Common dominant species include Salix alaxensis, S. glauca,S. barclay;, S. planifolia, S. lanata, and S. bebbiana. Scattered trees, primarily whitespruce and balsam poplar, may be present but total less than 10 percent cover. Lowshrubs are unusual, but Salix brachycarpa, Rosa acicularis, Shepherdia canadensis,or others are sometimes present. The herb layer may be sparse or dense. If sparse,it is usually composed of species common in seral herb communities, such asOxytropis spp., Astragalus spp., Epilobium latifolium. and Artemisia spp.: denser herb