The Alaska Vegetation Classification - Alaska Geobotany Center ...

.A. 1.c. Closed Sitka Sprucewestern Hemlock ForestDescrlptlon-These communities are dominated by Sitka spruce and westernhemlock. The spruce provides 35 to 60 percent cover and constitutes mOSt 01 theoverstory. Mature spruce trees generally are 30 to 50 meters (95 to 145 ft) tall and50 lo 100 centimeters (20 to 40 in) d.b.h. Hemlock usually provides an understory25 to 40 meters (80 to 125 ft) high with 30 to 60 percent cover. Average diameter ofmature hemlock is 40 to 65 centimeters (15 to 25 in). Other tree species areuncommon.A well-developed shrub layer 1 to 1.5 meters (3 to 5 ft) tall is usually presentand consists of combinations of Oplopanax horridus, Vaccinium spp., and Rubusspectabilis. Common ferns and herbs include Gymnocarpium dryopteris, Dryopterisdilatata, Coptis aspleniifolia, Cornus spp., Rubus pedatus, Maianthemum dilataturn,Lysichiton americanum, Tiarella trifoliata, and Streptopus spp.Dlstrlbutlon and site characterlstlcs-Closed Sitka spruce-westem hemlock standsare common in southeastern Alaska and in a narrow coastal strip in south-centralAlaska, mostly at low elevations on alluvial fans, flood plains, footslopes, and upliftedbeaches. These communities occur on deep, well-drained, welldeveloped soils oninterfluves and on poorly drained, weakly developed soils on lowlands subject toflooding. They also are found at midelevations on steep slopes near periodicallyactive channels and snow avalanche paths and on mass-wasting slopes.Successional status-Sitka spruce-western hemlock communities are climax ornear-climax.Closely related types-These communities are similar to both Sitka sprucecommunities and western hemlock communities but have substantial quantities ofboth tree species. They also are similar to open Sitka spruce-western hemlockcommunities but have greater tree cover.Primary referenc+Martin and others 1985.Communities-Picea sitchensis-Tsuga heterophylWLysichiton americanuWSphagnumspp. (Alaback 1980b, Neiland 1971a, Stephens and others 1969). Piceasitchensis-Tsuga heterophyllalvaccinium spp.-Menziesia ferruginea (Neiland 1971a.Stephens and others 1969). Picea sitchensis-(Tsuga heterophy/la)'/Oplopanaxhorr;dus/Lysichiton amerrcanurn (Martin and others 1985). Picea sitchensis-(Tsugaheterophylla)(see footnote l)/Vacciniurn sppJOplopanax horridus (Marlin and others1985). Picea sitchensis-(Tsuga heterophylla)(see footnote l)/Vacciniumspp. (Martinand others 1985). Picea sitchensis-(Tsuga heterophy//a)(see footnote l)/Vacciniumspp./Lysichiton arnericanurn (DeMeo and others 1989).' Name in parentheses not included in the plant associationname by Martin and others (1985).58