The Alaska Vegetation Classification - Alaska Geobotany Center ...

LA. 1.d. Closed Western Hemlock-Sitka Spruce-(Western Redcedar) ForestDescription-These communities are dominated by western hemlock. Sitka spruceis codominant but secondary to the hemlock in cover. Stands often are fairly open,but have about 60 percent overstory cover or more. South of 570 north latitude,western redcedar (Thuja plicata) often is included in stands lo the point of beingcodominant. Mature trees range from 38 to 50 centimeters (15 lo 20 in) in d.b.h. andfrom 24 to 30 meters (75 to 90 ft) in height. Western hemlock seedlings are common.A well-developed shrub layer 1 to 1.5 meters (3 to 5 it) tall is dominated by somecombination of Oplopanax horridus, Vaccinium spp., Menziesia ferruginea, andRubus spectabilis. Common ferns and herbs include Gymnocarpiurn dryopferis,Dryopferis dilafafa, Rubus pedafus, Tiarella frifoliafa, and Lysichiton americanum.Distribution and site characteristics-These communities are common in southeasternAlaska and in a narrow strip along the coast of south-central Alaska at allelevations below the subalpine zone. They generally occur on steep, stony slopeswhere the soil is shallow but well drained. Rock outcrops are common. Soils aremineral and often disturbed by periodic surface and subsurface water flows. Theforest floor layer is variable in thickness. A distinct microtopography of hummocksand hollows may be present.Successional status-These are climax communities.Closely related types-These communities are similar to Sitka spruce-westernhemlock communities but have more hemlock and less spruce. They also are similarto Sitka spruce communities and western hemlock communities but differ in that bothspecies are well represented.Primary reference-Marlin and others 1985.Communities-Tsuga heterophylla-Picea sitchensis-(Thuja plicafa)/Vacciniumspp./Rhytidiadelphus loreus (Alaback 1980b, Neiland 1971a, Stephens and others1969). Tsuga heferophylla-Picea sifchensis-(Thuja plicata)/Lysichifon americanurWSphagnum recurvum (Neiland 1971a). Tsuga heferophylla-(Picea sifchensis)(seefootnote l)/Vaccinium spp./Oplopanax horridus (Martin and others 1985). Tsugaheterophylla-(Picea sifchensis)(see footnote l)/Vaccinium spp./Lysichifonamericanum (Martin and others 1985).1.A.l.e. Closed Western Hemlock-Alaska-CedarDescription-These communities are dominated by western hemlock and Alaskacedar(Chamaecyparis noofkafensis). Sitka spruce is uncommon, and mountainhemlock (Tsuga merfensiana) occurs in minor quantities. Canopy cover is usually atthe lower end of the closed category (55 to 70 percent). Mature trees average 24 to30 meters (75 to 90 it) tall and 38 to 50 centimeters (15 to 20 in) d.b.h. Hemlockseedlings are abundant; Alaska-cedar seedlings are uncommon.A well-developed shrub layer 1 to 1.5 meters (3 to 4.5 It) tall is dominated byVaccinium spp. and Menziesia ferruginea. Common ferns and herbs includeGymnocarpium dryopferis, Blechnum spicanf, Cornus spp., Rubus pedafus,Coptis aspleniifolia, and Lysichiton americanum.59