The Alaska Vegetation Classification - Alaska Geobotany Center ...

Closely related types-These wmmunities are closely related to western hemlock-Alaska-cedar communities but have more western redcedar and less Alaska-cedar.Western hemlock-Alaska-cedar communities often are found north of the range ofwestern redcedar but on sites similar to those occupied by western hemlock-westernredcedar farther south. Western hemlock-western redcedar communities also aresimilar to open mixed conifer communities but have greater arboreal cover and astronger dominance of western hemlock and western redcedar.Prlmary references-Alaback 1980b. Stephens and others 1969.Communities-Tsuga heferophylla-Thuja plicafa/Vaccinium spp./Lysichifonamericanurn (Alaback 1980b, Stephens and others 1969).LA. 1.h. Closed Silver Fir-Western Hemlock ForestDescrlptlon-These stands are dominated by Pacific silver fir (Abies amabilis)and western hemlock. Sitka spruce and western redcedar also may be important.Maximum size of silver fir is approximately 115 centimeters (45 in) in diameter and47 meters (143 ft) in height. A well-developed and productive shrub layer is presentand is dominated by Vacciniurn alaskaense. Other common shrubs include Menziesiafermginea and Rubus specfabilis. Common ferns include Dryopferis dilafafa, Afhyriurnfilix-femina, and Gymnocarpium dryopferis. The herb layer consists primarily ofCornus canadensis and the low trailing shrub Rubuspedafus. Common mossesinclude Rhyfidiadelphus loreus, Hylocomium splendens, and Plagiotheciumundulafum.Distributlon and site characteristics-Silver fir-western hemlock stands arescattered in southernmost southeast Alaska (south of lat. 55'15' N.), primarily onnorth- and east-facing slopes. They are most common on low- and mid-elevationslopes but sometimes extend from tidewater to tree line. Pacific silver fir shows thestrongest dominance in stands in the northern part of its Alaska range.SUCCeSSlOnal status-This is a climax forest type. Some stands have been loggedin the past and have returned to silver fir codominance.Closely related types-Pacific silver fir may be present in Sitka spruce-westernhemlock stands and western hemlock-Sitka spruce-(western redcedar) stands.Primary reference-luday and others 1980.Communities-Abies amabilis-Tsuga heferophylla (Juday and others 1980).I.A. 1.1. Closed Subalpine Fir ForestDescription-These communities are dominated by subalpine fir (Abies lasiocarpa).Other important tree species include Sitka spruce, mountain hemlock, and Alaskacedar.The largest subalpine firs are on the order of 18 meters (55 R) tall and 45 centimeters(18 in) d.b.h. Most trees are considerably smaller, at least on the islandsites. On severely wind-exposed sites, subalpine fir readily forms krummholz bygrowing in dense mats as low as 15 centimeters (6 in). Sitka spruce and mountainhemlock, on the other hand, when present on these exposed sites, do not as readilyform mats but occur as clumps of small trees surrounded by low mats of subalpinefir. Layering appears to be the primary form of reproduction, at least on the islandsites. Although abundant cones are formed, the seeds frequently are not viable.Common understory species include fauria crista-gall!, Cornus canadensis, andfhyllodoce aleutica.62