The Alaska Vegetation Classification - Alaska Geobotany Center ...

lll.C.2.b. Foliose and Fruticose LichenFigure 76-A community of fruticose lichens,primarily Ceiraria nivalis and Thamnoliavermicularis, on rock scree in arctic Alaska.Descriptlon-Foliose and fruticose lichen communities are dominated by foliose andfruticose lichens, such as species of Cladonia, Cladina, and Stereocaulon (fig. 76).Crustose lichens may be common. Mosses are uncommon. Vascular plants areabsent or nearly so. This unit is reserved for communities where lichens are commonand other life forms are absent or nearly so.Distribution and site characteristics-Foliose and fruticose lichen communitiesare most important in southwestern and northwestern Alaska, where they occur onfellfields and exposed ridges. These sites are slightly more amenable to plant growththan are those occupied by crustose lichen communities, but the sites are still toosevere for vascular plant growth.Successional status-Successional relations are unknown.Closely related types-Foliose and fruticose lichen communities are similar tocrustose lichen communities but are dominated by foliose and at least some fruticoselichens. They also are similar to some lichen-rich open dwarf shrub types, butvascular plants are absent or very scarce. Dwarf shrubs or sedges, or both, havebeen common in all the fruticose lichen-rich communities reported to date. Communitieswith a dense cover of lichens but with some shrub or herbaceous coverhave been placed in dwarf scrub or graminoid herbaceous tundra types in thisclassification.Photographs-Figure 76, this publication.Primary references-None known.Communities-Cladina slellaris-Sphaerophorus fragilis (Klein 1959). Cladoniaspp.-Cetraria spp. (Johnson and others 1966). Cladonia spp.-Cladina spp. (Brockand Burke 1980). Alectoria spp.-Stereocaulon spp. (Brock and Burke 1980).1II.D. Aquatic HerbaceousThese are communities dominated by plants with leaves that float on the watersurface or grow entirely below the surface of the water.111.0.1. Freshwater Aquatic HerbaceousThis unit includes aquatic communities in fresh water.203