Definition: The Moss-Lichen Wetland Class includes areas where mosses or lichens cover at least 30 percent of substrates other than rock and where emergents, shrubs, or trees alone or in combination cover less than 30 percent. Water Regimes include Seasonally Flooded, Seasonally Flooded-Saturated, Continuously Saturated and Seasonally Saturated. 


Description: Mosses and lichens are important components of the flora in many wetlands, especially in the North, but these plants usually form a ground cover under a dominant layer of trees, shrubs, or emergents. In some instances higher plants are uncommon and mosses or lichens dominate the flora. Such Moss-Lichen Wetlands are not common, even in the northern U.S. where they occur most frequently. 


Subclasses and Dominance Types: 


Moss - In this Subclass, the areal coverage of mosses exceeds that of lichens. Moss dominated wetlands are most abundant in the far northern boreal forests and Arctic tundra, where they are dominated by peat mosses such as Sphagnum fuscum and S. warnstorfii. These wetlands are typically called bogs (Golet and Larson 1974; Jeglum et al. 1974; Zoltai et al. 1975), whether Sphagnum or higher plants dominate. In Alaska, Drepanocladus revolvans, D. lycodiodes, and the liverwort Chiloscyphus fragilis may dominate shallow pools with semipermanent water. Other mosses, including Campylium stellatum, Aulacomnium palustre, A. turgidum and Oncophorus wahlenbergii, are typical of wet, saturated soils in these regions (Britton 1957, Drury 1962). 


Lichen - In this Subclass, the areal coverage of lichens exceeds that of mosses. Lichen Wetlands also are a Northern Subclass. Reindeer moss (Cladina and Cladonia), the principal Dominance Type, occurs primarily in boreal and Arctic regions. Lichen cover is generally elevated above moss, sedge-moss, or dwarf shrub-sedge-moss layers. Pollett and Bridgewater (1973) described areas with mosses and lichens as bogs or fens, the distinction being based on the availability of nutrients and the particular plant species present. The presence of Lichen Wetlands has been noted in the Hudson Bay Lowlands (Sjörs 1959) and in Ontario (Jeglum et al. 1974).

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