The Alaska Vegetation Classification - Alaska Geobotany Center ...

1.8.3. Broadlead WoodlandFigure 32-Broadleaf woodland ofpaper birch with a lichen and mosslayer ot the lichens Cladina spp.,Cladonia spp., Cetraria spp., andStereocaulon spp. and the mossRhacomitrium uliginosum on awell-drained gravel ndge in northerninterior Alaska.Broadleaf woodland communities have from 10 to 25 percent total tree cover. Atleast 75 percent of this total tree cover is contributed by broadleaf tree species.I.B.3.a.Paper Birch WoodlandDescription-Paper birch woodlands are characterized by open-grown paper birch,which has roughly 10 to 25 percent cover (fig. 32). The birches usually are multistemmedand rather stunted in growth form. Typical tree heights are 6 to 10 meters(20 to 32 ft) and tree diameters range up to 20 centimeters (8 in) but usually are lessthan half that. The ground cover consists primarily of fruticose lichens of the generaCladonia, Cladina, Cetraria, and Stereocaulon. Lichen cover tends to be sparser thanin the white spruce woodland, possibly because of increased litter fall. Shrubs andherbs are not important components of communities that have been described.Distribution and slte characteristics-Paper birch woodlands occur on dry sites innorthwestern Alaska and northern interior Alaska. They have been reported growingon stabilized sand dunes and coarse alluvial gravels. Permafrost is deep below thesurface or absent from these soils.Successional status-The successional relations of these communities is unknown.Similar sites also have white spruce woodlands with a few scattered, subordinatebirches. Possibly the pure birch stands owe their existence to severe fire or otherdisturbances. Perhaps white spruce will replace the birch in the absence of furtherdisturbance as it does on many other sites; however, evidence for this has not beenreported.Closely related types-Paper birch woodlands are similar Io open paper birchforests but have less tree cover. Sparsely wooded stands may grade into some typeof shrub tundra or dryas-lichen tundra.Photographs-Racine 1976, figure 9; figure 32, this publication.Primary referenceflacine 1976.Communities-Befu/apapyrifera/C/adonia spp. (Racine 1976).