Aulacomnium palustre, the bog groove-moss or ribbed bog moss, is a moss that is nearly cosmopolitan in distribution. It occurs in North America, Hispaniola, Venezuela, Eurasia, and New Zealand. In North America, it occurs across southern arctic,"Arctic" refers to treeless areas underlain with continuous permafrost; "subarctic" refers to mixed tundra and open forest underlain with discontinuous permafrost. subboreal,"Subboreal" refers to areas in southern Canada, the Great Lakes states, and the Northeast that were once underlain with permafrost that has since melted. and boreal"boreal" refers to northern coniferous forests where permafrost occurs only sporadically. regions from Alaska and British Columbia to Greenland and Quebec. Documentation of ribbed bog moss's distribution in the contiguous United States is probably incomplete. It is reported sporadically south to Washington, Wyoming, Georgia, and Virginia.
Habitat types and plant communities Ribbed bog moss is frequent in arctic to subboreal wetlands. Moss assemblages are typically diverse in northern (arctic, subarctic, and boreal) plant communities, and individual moss species often have low cover and/or frequency. Moss species with coverages of 2% to 4% can be common to dominant in boreal communities, although ribbed bog moss attains coverages as great as 40% in some boreal communities.
Ribbed bog moss grows in open and forested wetland communities. In unforested northern communities, ribbed bog moss is found in sedge (Carex spp.) meadows, sphagnum (Sphagnum spp.) peatlands, heath-sedge fens, and willow (Salix spp.)-dominated fens. In forests, ribbed bog moss grows in the ground layer of boreal and subboreal white spruce (Picea glauca), black spruce (P. mariana), mixed spruce-tamarack (Larix laricina), and jack pine (Pinus banksiana) fens and bogs of Alaska, Minnesota, and Canada and in boreal spruce-birch (Betula spp.) forests of Alaska and northwestern Canada. Mosses are abundant in taiga forests of interior Alaska and Canada, forming characteristic strata in nearly every taiga forest type.
Less is known of ribbed bog moss associations south and east of Minnesota, although ribbed bog moss has been noted in some swamp, coniferous and/or hardwood bog, and grassland communities. Ribbed bog moss grows in red maple (Acer rubrum) swamps of Long Island, New York, and Little listed ribbed bog moss as common (1-4% frequency) in Atlantic white-cedar (Chamaecyparis thyoides) swamps of southern New Jersey.Little, S. 1951. Observations on the minor vegetation of the pine barren swamps in southern New Jersey. Bulletin of the Torrey Botanical Club. 78(2): 153-160. Ribbed bog moss is also common in jack pine, aspen (Populus spp.), and mixed-hardwood forests of the Great Lakes states and southern Canada. Ribbed bog moss grows on tallgrass prairie in Kansas and Arkansas. In the Pacific Northwest ribbed bog moss occurs in alpine, subalpine, wet and dry coniferous forest, and open peatland communities. In a survey of alpine and unforested subalpine communities of the North Cascade Range in Washington and British Columbia, ribbed bog moss occurred in graminoid, forb, heath, and willow communities.
General botanical characteristics Mosses have 2 phases in their life cycle: the gametophyte (n) and sporophyte (2n) generations. Each generation is morphologically distinct.
Gametophytes Ribbed bog moss stems comprise most of ribbed bog moss's biomass and are easily visible. Stems are erect and spreading in habit, forming clumps or lawns. They range from long; most stems are vegetative but some bear reproductive organs. Short vegetative stems may end in a stalk-bearing clusters of gemmae. Ribbed bog moss is heterothallic, with male and female reproductive organs borne on separate reproductive shoots. Male and female stems develop antheridia and archegonia, respectively, at their tips. Approximately the top of both vegetative and reproductive stems is alive; lower stem tissue is usually dead. Ribbed bog moss leaves are bright yellowish-green to green; their bright color sometimes gives ribbed bog moss an incandescent appearance ("glow moss"). Bright leaves that contrast starkly with the reddish-brown stems typically make ribbed bog moss the most conspicuous species in moss assemblages. The leaves are lanceolate in shape and often tomentose, becoming twisted and brown when dry. They range from 3 to 5 mm long. Ribbed bog moss anchors to the substrate with rhizoids. Because ribbed bog moss lacks vascular tissue, water uptake occurs by osmosis and capillary action. A network of capillary spaces between stems and rhizoids enhances water uptake; ribbed bog moss usually absorbs water more efficiently than associated sphagnum mosses.
Sporophytes Sporophytes grow out of archegonia. The sporophyte consists of a foot that anchors the sporophyte to the archegonia, a stalk, and a spore capsule. Ribbed bog moss stalks are vertically straight and about long. Ribbed bog moss is named for its distinct spore capsule, which is strongly ribbed, cylindrical, and about 4 mm long. The capsule is capped with a calyptra.
Regeneration processes Ribbed bog moss regenerates sexually and vegetatively.
Gametophyte dispersal and establishment A spore is the first growth stage of a developing gametophyte. When the spore capsule matures, ribbed bog moss's calyptra splits along the side, exposing spores. Release of the exposed spores requires dry weather and is governed by a row of "teeth" that ring the capsule's top. The capsule teeth are hygroscopic, bending outward when air is dry and permitting spores to fall. Wind disperses ribbed bog moss spores long distances by shaking the capsule. When air is moist, the teeth bend inward, holding the spores within the capsule. The spores require a moist substrate to germinate. A germinated spore develops into a protonema (a branched, threadlike structure). Rhizoids grow down from the protonema and penetrate the substrate. Stems arise from buds that develop on the protonema surface. As stems grow, they develop their own rhizoids and become independent of the protonema. Mature male and female stems develop antheridia and archegonia, which produce sperm and eggs, respectively. Ribbed bog moss antheridia do not develop synchronously on the same stem. Mature and immature antheridia are intermixed on individual male shoots; therefore, sperm cells on the same stem do not all develop at the same time. However, sperm cells within a single antheridium have synchronous development. Fertilization requires a moist or saturated environment. Before fertilization, the antheridium absorbs water and swells, forcing the spore cap off. Rain may splash sperm into the archegonium, or sperm may swim to the archegonium.
Spore banking Ribbed bog moss may germinate from spores stored in the substrate, but banked spores are probably less important to ribbed bog moss regeneration than freshly dispersed spores. Ross-Davis and Frego found that annual dispersal deposited a far greater number of moss spores on boreal substrates compared to the number of spores buried in the spore bank.Ross-Davis, Amy L. and Katherine A. Frego. 2004. Propagule sources of forest floor bryophytes: spatiotemporal compositional patterns. The Bryologist. 107(1): 88-97.
Breeding system Ribbed bog moss is dioecious.
Sporophyte development Ribbed bog moss's sporophyte generation develops from the fertilized egg. Eggs are fertilized within the archegonium. The sporophyte embryo grows rapidly, differentiating into foot, stalk, and capsule tissue. Spores develop within the capsule.
Vegetative regeneration Ribbed bog moss reproduces asexually from specialized gametophyte tissues and from plant breakage. It reproduces frequently from gemmae. Ribbed bog moss may also regenerate when paraphyses (minute filaments arising from ribbed bog moss's antheridia) detach. In the laboratory, 12.5% of detached ribbed bog moss paraphyses developed into propagules. Ribbed bog moss establishes readily when chunks of ribbed bog moss shoots are moved to new sites by soil movement or transplanting. Ribbed bog moss is apparently competitive in its ability to establish from stem chunks. In a laboratory experiment, ribbed bog moss that was collected from an Alberta peatland, shredded, and placed on a peat substrate showed greatest frequency (100%) of 4 moss species so treated. Ribbed bog moss also showed fastest growth relative to the other mosses throughout the 125-day experiment.
Growth Ribbed bog moss growth is robust. It showed a "tall and dense growth habit" in a greenhouse common garden; ribbed bog moss, juniper hair cap moss (Polytrichum juniperinum), and papillose sphagnum (S. papillosum) crowded out 3 other moss species. Dry climate slows or stops ribbed bog moss growth. On the Boreal Ecosystem Research and Monitoring Sites study area in Saskatchewan, ribbed bog moss had a negative mean annual growth rate in a drought year (2003). Mean annual growth rate in a wet year (2004) was 2.7 mm. Ribbed bog moss was sensitive to saturated conditions in the wet year; stem lengths were greatest on relatively drier microsites, and ribbed bog moss growth rate increased slightly with increasing depth to the water table.
Site characteristics Ribbed bog moss is a habitat generalist. It was, for example, 1 of 6 mosses having broad ecological amplitude in a survey of bryophyte habitats on peatlands across Alberta's Mackenzie River basin. Ribbed bog moss tolerates a wide range of moisture levels, substrates, nutrient loads, terrain, and climates.
Moisture regime Ribbed bog moss generally grows on wetlands including fens, bogs, marshes, pond margins, streambanks, wet meadows, and riparian shrublands. In subalpine fir forests of central Idaho, ribbed bog moss occurs on seeps and springs that remain moist throughout the fire season. Ribbed bog moss is an indicator species of wet to very wet soils in Canada. In northern British Columbia, ribbed bog moss is an indicator species of undisturbed wet conifer sites. The white spruce/field horsetail/ribbed bog moss association occurs on the wettest white spruce forests in subboreal British Columbia; the water table is near the soil surface for most of the growing season. In a geothermal meadow in Haida Gwaii, British Columbia, ribbed bog moss occurred on sites with high local humidity (31-66%) due to nearby thermal pools. Ribbed bog moss did not grow on dry sites, although drained microsites may favor ribbed bog moss growth on otherwise saturated substrates. Ribbed bog moss does not tolerate salt spray, which prevents its establishment on coastal dunelands.
Ribbed bog moss is not confined to wet sites in all areas. Some forests with ribbed bog moss dry in late summer, and ribbed bog moss grows on relatively xeric hummock mounds on bogs in Birds Hill Provincial Park, Manitoba. Ribbed bog moss occupies both dry and wet sites on the Boreal Ecosystem Research and Monitoring Sites study area. It dominates relatively dry, shaded microsites in the area; the water table is below ground, and there is 30% to 60% black spruce and/or tamarack cover.
Substrates Ribbed bog moss is primarily a ground-layer species, but it does not require a particular substrate to establish and grow. It is most common on peat but also grows on thinner organic soils and other substrates. Ribbed bog moss frequently grows on peat overlying permafrost in Alaska and northern Canada. On northern peatlands, the peat layer generally ranges from thick, and organic content of the soil layer is high. Studies on peatlands in Quebec showed ribbed bog moss "preferred sites with high organic matter depth" (P<0.01). Ribbed bog moss grows on organic surface layers overlying varying soil textures. Ribbed bog moss also grows on burned substrates including ash, mineral soil, scorched organic soil, scorched peat, and scorched downed woody debris.