The Alaska Vegetation Classification - Alaska Geobotany Center ...

1.c.7.d. Closed Quaking Aspen-Spruce ForestFigure 3GClosed mixed forest of aspen andwhite spruce with an understoty of Linnaeaborealis, Vaccinium vifis-idaea. Lycopodiumcomplaflafum, and Epilobium angusfifolium ininterior Alaska. (PhotqjraphoounesyA.Voungbload.)Description-These forests are codominated by quaking aspen and white spruce,black spruce, or both (fig. 34). Tree canopy coverage is over 60 percent. Smallquantities of balsam poplar may be present in these stands. Spruce seedlings andsaplings are usually common. Aspen root suckers may be abundant, but thesenormally live only a few years and then die. The largest trees of both aspen andwhite spruce in mature and overmature stands reach about 25 to 30 centimeters(10 to 12 in) d.b.h. and 18 to 22 meters (60 to 72 ft) in height. The aspen in aspenblackspruce stands is smaller. The largest black spruce reach 6 to 7 centimeters(2.5 to 3 in) d.b.h. and 4 to 12 meters (12 to 40 ft) in height. The aspen are tallerthan the spruce in both cases and begin to die if they are overtopped. The aspenare always even aged; the spruce are usually uneven aged as they come in slowlyafter the initial establishment of the stand. Stand densities are high in young stands,about 2,500 to 6,000 stems per hectare (1,000 to 2,40O/acre) at 20 years. Densitydecreases with age, reaching 1,500 aspen stems per hectare (600/acre) and 400black spruce stems per hectare (160/acre) in aspen-black spruce stands at maturity(60 to 70 years). Density in aspen-white spruce stands decreases to 1,000 to 1,500stems per hectare (400 to 600/acre) at about 100 years.Occasional tall shrubs such as Alnus crispa, Salix bebbiana, S. scouleriana, andperhaps other species of Salix, usually are present. Rosa acicularis commonly formsan intermittent low shrub layer. Common dwarf shrubs include Vaccinium vifis-idaea,V. uliginosum, Arctostaphylos uva-ursi, Linnaea borealis, and Shepherdia canadensisin aspen-white spruce stands, and Vaccinium vitis-idaea, V. uliginosum, Ledumgroenlandicum, Linnaea borealis, and Arcfosfaphylos rubra in aspen-black sprucestands. Common herbs include Epilobium angusfifolium, Equisetum spp., Cornuscanadensis, Calamagrostis canadensis, Mertensia paniculafa. and Pyrola spp.Common mosses on the forest floor of both white spruce and black spruce typesare various combinations of Drepanocladus spp., Hylocomium splendens, andPolyfrichum spp., with the addition of Pleurozium schreberi in stands where blackspruce is present. Pelfigera aphfhosa is a common lichen.101