Mosses have 2 phases in their life cycle: the gametophyte (n) and sporophyte (2n) generations. Each generation is morphologically distinct. The following description of ribbed bog moss provides characteristics of each generation that may be relevant to fire ecology; it is not meant for identification. Keys for identification are available in these sources: [25,33].
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 1 to 4 inches (3-9 cm) long; most stems are vegetative but some bear reproductive organs. Short vegetative stems may end in a stalk bearing clusters of gemmae [25,33,106]. Ribbed bog moss is heterothallic [33,133], with male and female reproductive organs borne on separate reproductive shoots. Male and female stems develop antheridia and archegonia, respectively, at their tips [33,133,138] (see the Life cycle figure). Approximately the top 0.6 inch (1.5 cm) of both vegetative and reproductive stems is alive; lower stem tissue is usually dead [14]. 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 [25,33,106]. Ribbed bog moss anchors to the substrate with rhizoids [138]. 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 [4].
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 1.8 inches (4.5 cm) long [133]. Ribbed bog moss is named for its distinct spore capsule, which is strongly ribbed, cylindrical, and about 4 mm long [25,33,106]. The capsule is capped with a calyptra [133].
Ribbed bog moss is nearly cosmopolitan in distribution [33,133]. It occurs in North America, the Dominican Republic, Venezuela, Eurasia, and New Zealand. In North America, it occurs across southern arctic, subboreal, and boreal regions from Alaska and British Columbia to Greenland and Quebec [33]. Documentation of ribbed bog moss's distribution in the contiguous United States is probably incomplete. It is reported sporadically south to Washington [35], Wyoming, Georgia, and Virginia [7,90,107]. A distributional map of ribbed bog moss was not available as of 2008. NatureServe provides a list of states and provinces where ribbed bog moss is known to occur.
In this review, "arctic" refers to treeless areas underlain with continuous permafrost, "subarctic" refers to mixed tundra and open forest underlain with discontinuous permafrost, "boreal" refers to northern coniferous forests where permafrost occurs only sporadically, and "subboreal" refers to areas in southern Canada, the Great Lakes states, and the Northeast that were once underlain with permafrost that has since melted [139].
Fuel management: Peatland fires are difficult to suppress. Hawkes [62] rated white spruce bogs and fens as "moderate" for ease of ignition and rate of spread, "high" for crown fire potential, and "highly difficult" for on-the-ground suppression due to extremely deep duff or peat. Fuel loads varied due to variation in shrub and herb cover, depth and continuity of dead surface fuels, and depth of moss and organic soil layers [62]. Dry mosses provide a continuous surface layer of fuels [141], and once mosses dry, light rains may not be enough to remoisten them. Ferguson and others [40] found that a "substantial amount" of precipitation was required to rewet dry mosses in Alaska. Prior to the July 1999 FrostFire prescribed burn near Fairbanks, Alaska, they monitored moisture levels on feather moss-dominated sites. Drying time varied significantly between feather moss species and with peat depth: Hylocomium spp. dried faster than Pleurozium spp., and shallow peat dried faster than deep peat. Ribbed bog moss grew in the feather moss community [40], although its drying time was not measured. Fuel load measurements for ribbed bog and plant communities where ribbed bog moss is important are provided in Fuels.
Lack of data make it impossible to recommend moss- and peat-layer moisture levels that will sustain but help contain a prescribed fire. Further experimental studies such as the FrostFire prescribed burn are needed in order to provide guidelines for fire suppression and wildland fires for resource benefit in arctic, subarctic, and boreal peatlands.
Salvage logging: Ribbed bog moss may tolerate postfire logging (see Logging and Plant Response to Fire), although few studies on the effects of salvage logging on ribbed bog moss were available as of 2008. Further studies are needed on the combined effects of fire and logging on ribbed bog moss and other groundlayer species.
Climate change: Northern peatland fires influence carbon emissions directly through biomass burning and indirectly through impacts on ecosystem processes. In 1998, Zoltai and others [141] estimated that net global rate of peat accumulation exceeded the net rate of peat depletion from fire and microbial decomposition. Increased temperatures in the northern latitudes, however, may increase rates of depletion of carbon stores in northern peatlands and increase greenhouse gas emissions in the future [64].
Secondary emissions due to increased nutrient loads and microbial activities after fire may exceed greenhouse gas emissions from peatland fires. Combustion emissions of carbon differ by peatland type. Permafrost bogs generally have the largest total area burned, and fens the smallest (see Fire size and frequency), so permafrost bogs tend to have the greatest carbon emission releases during fire and fens the least. Extensive fires in remote subarctic areas underlain by permafrost contributed an estimated 85% of total carbon emissions from fires in northern peatlands in the last millennium [141].
Possible responses of northern peatlands to projected climate changes include increased carbon loss during extended thaw periods, increased thaw depth of permafrost, increased microbial activity due to warmer temperatures, and reduced moisture levels on peat surfaces [85,141]. Drier peat surfaces could increase wildfire frequencies and microbial decomposition of peat. Zoltai and others [141] predict that a drier climate will increase fire frequency, intensity, and consumption of deep peat layers.
A warmer climate is expected to cause extensive degradation of northern permafrost areas [131,139,141]. Fire may accelerate rate of permafrost degradation by directly thawing permafrost, removing insulating surface peat above permafrost, and/or creating a heat-absorbing black surface that accelerates melting [131,141]. Northern peatlands often develop thermokarsts (former permafrost areas that sink below surrounding fens or bogs) after fire melts the underlying permafrost layer. Thermokarsts characteristically support ribbed bog moss-dominated or other moss lawns after fire [131]. In northern boreal zones, permafrost re-forms over thermokarsts after the peat layer becomes thicker than 16 inches (40 cm). Taiga communities require long period of time to redevelop once permafrost has melted. In northern boreal black spruce forests, the cycle of fire, permafrost melt, postfire moss growth, peat development, permafrost development under peat, and reforestation on permafrost requires 500 years or more [140,141]. Moss recolonization may be the shortest stage of this long process: ribbed bog moss and other peat-forming mosses are expected to "rapidly colonize" the wet depressions that sometimes develop after permafrost melts [141].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 [92]. 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 [115] including fens, bogs, marshes [25,78,89,106,115,133], pond margins, streambanks, wet meadows, and riparian shrublands [33,99,114]. In subalpine fir forests of central Idaho, ribbed bog moss occurs on seeps and springs that remain moist throughout the fire season [80,113]. Ribbed bog moss is an indicator species of wet to very wet soils in Canada [80,99]. In northern British Columbia, ribbed bog moss is an indicator species of undisturbed wet conifer sites [86]. 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 [115]. In a geothermal meadow on Queen Charlotte Island, 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 [52], although drained microsites may favor ribbed bog moss growth on otherwise saturated substrates (see Growth). Ribbed bog moss does not tolerate salt spray, which prevents its establishment on coastal dunelands [13].
Ribbed bog moss is not confined to wet sites in all areas. Some forests with ribbed bog moss dry in late summer [80,99,115], and ribbed bog moss grows on relatively xeric hummock mounds on bogs in Bird's Hill Provincial Park, Manitoba [119]. 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 20 to 26 inches (50-65 cm) below ground, and there is 30% to 60% black spruce and/or tamarack cover [4].
Substrates: Ribbed bog moss is primarily a groundlayer species, but it does not require a particular substrate to establish and grow [16]. It is most common on peat [2,15,112,122] but also grows on thinner organic soils [44,112] and other substrates [16,38,44,101]. Ribbed bog moss frequently grows on peat overlying permafrost in Alaska and northern Canada [2,112,122]. On northern peatlands, the peat layer generally ranges from 38 to 102 inches (15-40 cm) thick [2], and organic content of the soil layer is high [80]. Studies on peatlands in Quebec showed ribbed bog moss "preferred sites with high organic matter depth" (P<0.01) [15]. Ribbed bog moss grows on organic surface layers overlying varying soil textures [21,112]. Ribbed bog moss also grows on burned substrates including ash [101], mineral soil [57], scorched organic soil, scorched peat [16], and scorched downed woody debris [16,38].
Ribbed bog moss grows on peat and other organic soil layers more often than on downed bark or wood [99], but is reported growing on woody debris or other dead wood in a few locations. In northern British Columbia, ribbed bog moss substrates included disturbed forest floors, logs, and stumps at 44%, 13%, and 3% frequencies, respectively [86]. Ribbed bog moss was found on downed woody debris in a mixed quaking aspen-paper birch-balsam fir (Populus tremuloides-Betula papyrifera-Abies balsamifera) forest in east-central Alberta [31] and on stumps in a mixed-hardwood forest in Wisconsin [44]. Ribbed bog moss rarely grows on standing live or dead wood [99].
Ribbed bog moss showed broad substrate tolerances in a greenhouse common pot study in Scotland. Ribbed bog moss vegetative propagules were sown with propagules of 6 other mosses to test substrate preferences. After 1 year, ribbed bog moss abundance was similar on heather (Calluna vulgaris) litter, European white birch (Betula pendula) litter, dead shrub litter, Scots pine (Pinus sylvestris) needles, sand, and sphagnum peat substrates. To test particle-size microsite preferences on peat substrates, the peat was broken into various fragment sizes from minute to large (<0.25 inch to >2 inches (0.63-5 cm)). Ribbed bog moss grew on peat of all particle sizes but was most frequent on small (0.5-1 inch (1.25-2.5 cm)) peat particles [5].
Water and substrate chemistry: The pH of water, peat, and/or soil is usually acidic to neutral in mires with ribbed bog moss [2,33,51,51,52,112,133], although ribbed bog moss tolerates mildly alkaline conditions [33,133]. For example, ribbed bog moss grows in extremely acidic peatlands overlying permafrost in spruce taiga of Alaska [122] but also grows in calcareous bogs in Bird's Hill Provincial Park [119]. In Minnesota, ribbed bog moss is reported from bogs ranging from 5.0 to 7.3 in pH [26]. A survey of bryophytes on peatlands across Alberta's Mackenzie River basin found ribbed bog moss was abundant on sites ranging from 4.5 to 7.5 in pH [92].
Mires are classified on pH and mineral gradients from extreme-poor (very strongly acid and low in calcium and magnesium) to extreme-rich (neutral to alkaline and high in calcium and magnesium) [72,110]. Fens are richer than bogs [68,91]. Ribbed bog moss occurs in poor [28,89] and rich [4,28,68] mires. On mires across British Columbia and Alberta, ribbed bog moss grows in mires with broad ranges of water pH and electrical conductivity [50], but is most common on strongly acidic peatlands (water pH <5.5) with moderate calcium and magnesium levels (<200 µS/cm**) [51]. Ribbed bog moss also grows in moderate-rich fens with higher pH and electrical conductivity values [50]. In a peat-core study in central Alberta, macrofossil ribbed bog moss was an indicator species of moderate-rich fens; ribbed bog moss occurred most often on mires that were moderately acidic (x pH=6.0) and had low electrical conductivity (x=125 µS/cm) and moderately high water tables (x= 8.7 inches (22 cm) deep) [3]. In a study of alpine mires in Italy, ribbed bog moss was intermediate in mire pH and mineral content compared to associated nonvascular and vascular plant species, occurring on both poor and rich mires. All associated mosses had narrower pH and mineral tolerances than ribbed bog moss [49]. Gignac [50] provides information on ribbed bog moss habitats in British Columbia and Alberta including ranges in pH, electrical conductivity, relative depth to the water table, and relative overstory cover [50].
**Mineral content of mire water is often measured as the electrical conductivity of dissolved salts and ions, reported in microsiemens over distance (µS/cm).
Nutrients: Field observations and laboratory experiments suggest that ribbed bog moss has broad tolerance and may be relatively insensitive to macronutrient concentrations [49,78,121]. On the Svalbard archipelago in Norway, ribbed bog moss grows on small "bird islands" where eider ducks, arctic terns, and other migratory birds nest offshore of the main island, Spitsbergen. Nitrogen levels on the bird islands are very high. On Spitsbergen Island, however, ribbed bog moss grows on dry hummocks and moist hummock edges, both of which have low nitrogen levels [121] but probably provide moisture levels that favor ribbed bog moss (see Landscape). In a laboratory experiment, nitrogen fertilizer initially slowed ribbed bog moss growth rate, but growth rates of ribbed bog moss with and without nitrogen were similar at the end of 125 days. Addition of phosphorus had no effect on ribbed bog moss growth [78].
Ribbed bog moss is listed as an indicator species of nitrogen-medium soils in British Columbia [80].
Landscape: Tundra and taiga areas where ribbed bog moss grows are generally flat to gently sloped [42,112], but local relief creates drainage patterns that often result in distinct moss assemblages. Site geologyÂincluding topography, bedrock composition, catchment hydrology, and basin bathymetryÂaffects wetland drainage and partially controls rates of transition from open water to bog [71,131]. Ribbed bog moss is common on hummocks, which tend to dry out faster than adjacent lowlands [92,121]. In British Columbia and Alberta, ribbed bog moss often dominates hummock tops that are surrounded by sphagnum peatlands [50,89]. Although ribbed bog moss generally attains greatest coverage on hummock tops, it sometimes forms lawns [50] and strings in low areas. In Labrador, tufted bulrush-mountain fly honeysuckle/ribbed bog moss associations occur on low strings of consolidated peat and on elevated peatlands. The low strings lie 38 to 76 inches (15-30 cm) above the water table and lack erosion patterns [47].
In Kluane National Park, Yukon, the white spruce/ribbed bog moss forest community occurs on poorly drained east- and north-facing slopes [62].
Elevation: There are few reports of ribbed bog moss's elevational tolerances. Ribbed bog moss is reported from 1,600 to 5,700 feet (500-1,750 m) in west-central Alberta [28] and at 827 feet (252 m) in Kosciucko County, Indiana [123]. In subalpine and alpine communities of the North Cascade Range in Washington and British Columbia, ribbed bog moss occurs on high-elevation (>7,380 feet (2,250 m)) sites that remain snow-free most of the year [35].
Climate: Ribbed bog moss occurs in arctic, subarctic, boreal, and subboreal zones with cold meso-thermal, oceanic, continental, or cold-humid climates [50,80,116]. It is more common in arctic, subarctic, and boreal than subboreal zones. A survey of bryophytes on peatlands across Alberta's Mackenzie River basin found optimal ribbed bog moss growth occurred on sites with annual temperatures ranging from 20 to 32 °F (-4 to 0 °C) [92]. In interior arctic, subarctic, and boreal zones, climate is strongly continental in the west, becoming more humid to the east. Climate shift from continental to humid generally occurs near Hudson Bay and Lake Superior [118,141]. In a study of moss habitats across British Columbia, Alberta, and Manitoba, ribbed bog moss was an indicator species for continentality of climate: it was the only moss common to all continental peatlands surveyed [51]. On sites from coastal British Columbia to central Alberta, ribbed bog moss was most common on subcontinental sites (intermediate between coastal and continental climates). Ribbed bog moss was intermediate on gradients ranking breadth of moss habitat niches. Climate factors evaluated included length of growing season, amount of precipitation during the growing season, temperature, and aridity. Feather mosses (Hylocomiaceae) and sphagnum mosses generally had wider niches and dominated more sites than ribbed bog moss [50]. Ribbed bog moss's rarity on all but cold sites in the lower 48 states suggests that ribbed bog moss does not tolerate long periods of warm weather. In a geothermal meadow on Queen Charlotte Island, British Columbia, ribbed bog moss was absent from sites where nearby thermal pools raised local soil temperatures above 86 °F (30 °C) [52].
Ribbed bog moss provides few known direct benefits to wildlife or livestock. Mosses in general are low in carbohydrates, proteins, and fats compared to vascular plants, and animals seldom graze them [82]. Caribou may eat mosses when little other forage is available [82,125]. Wildlife seeking cover probably avoid open areas dominated by ribbed bog moss or other low vegetation. In Wood Buffalo National Park, Alberta, aerial photos identified areas dominated by ribbed bog moss, bog Labrador tea, and/or Bebb willow as indicators of nonnesting habitat for whooping cranes [127].
American robins at the Mountain Lake Biological Station, Virginia, used ribbed bog moss as nest material [17].
Northern mires provide habitat for a variety of invertebrates including worms, crustaceans, arachnids, and insects, particularly mosquitoes, midges, and other flies [82].
As of 2008, there was almost no published information on phenology of ribbed bog moss. Phenology of mosses (Bryopsida) in general is rarely documented. Moss gametophytes typically develop during the warm spring or summer wet season [138] and desiccate and go dormant [40,141] when their substrate dries. Forman [44] proposed a protocol for describing moss seasonal development based on developmental stages. He noted the following phenology for ribbed bog moss [44]:
FIRE ECOLOGY OR ADAPTATIONS:
Fire adaptations: Ribbed bog moss has wind-dispersed spores [8,67,138]. Although not an adaptation specific to fire, wind dispersal enables ribbed bog moss spores to colonize burned substrates [16,38,101].
FIRE REGIMES in arctic, subarctic, and boreal peatlands are characterized by infrequent surface fires on open sites and infrequent combination crown and ground fires on forest and shrubland sites. Ground fires may continue smoldering for months, undercutting lower peat layers [65]. Climate, substrate moisture regimes, and fuel loads affect the size, frequency, and depth of peatland fires.
Prescribed fire in black spruce taiga near Fairbanks, Alaska. Frostfire Project. Climate and substrate moisture regimes: FIRE REGIMES differ from north to south in arctic, subarctic, and boreal wetlands due to the temperature gradient and from west to east in western continental and eastern humid climates due to the humidity gradient. North to south, charcoal deposits show that peatland fires were historically more frequent in arctic and subarctic wetlands compared to boreal wetlands. West to east, boreal peatland fires were probably more common historically in western continental than eastern humid climates [141]. For example, Kuhry [70] found 29 charcoal layers in a 5.2-foot (1.6 m) peat layer in northeastern Saskatchewan. In a New Brunswick study, charcoal layers were present in peat layers, but charcoal occurred mostly in trace amounts [132]. Fires in northeastern North America were likely small and patchy, rarely burning into the peat layer [45,136].Widespread peat fires typically occur in drought years [41]. Fire history studies in northern ecosystems show peat combustion was more common in bogs than fens, probably due to lower moisture levels and greater peat thicknesses in bogs [141]. Charcoal evidence of fire in fens has only been found at one site in Alberta [70]. However, direct observations prove that fens burn, especially in fall when vegetation is dry, but that fires tend to remain on the surface [141].
Water table depth affects susceptibility of mires to fire; surface peats may dry quickly when the water table is deep below ground. In boreal zones of northeastern North America, Zoltai and others [141] found water tables were deepest for bogs over permafrost and shallowest for open graminoid fens lacking a permafrost layer, making bogs over permafrost most susceptible (able to ignite and sustain combustion) to fire and open fens least susceptible to fire. Ribbed bog moss occurs in all the peatland types below.
Depth to free water or permafrost in subhumid climates of boreal North America [141]
Peatland type Mean depth (SD) Open fen 1.3 cm (1.3) Shrubby fen 13.6 cm (2.0) Treed fen 19.7 cm (1.4) Conifer swamp 31.1 cm (3.1) Bog 35.0 cm (1.6) Permafrost bog 52.8 cm (2.2)Water table fluctuations vary between years, seasons, and wetland types. In bogs, the water table may drop by a factor of 2 in drought years, and fire sometimes consumes lower peat layers in drought years. Water tables below fens generally fluctuate less than those below bogs during drought [141]. Permafrost can produce steep moisture gradients. Drainage patterns over deep permafrost sometimes result in dry peat on the surface and saturated peat just above the permafrost layer. Conversely, shallow permafrost may cause saturation of the peat surface by impeding downward water percolation. Permafrost elevates some sites into hummocks, which are preferred ribbed bog moss habitats. Hummocks may desiccate and burn more readily than lower, more saturated areas [141]. Fires on some hummocks in Alberta have produced enough heat to thaw underlying permafrost [140]. Fires may increase summer thaw of permafrost 30% to 50% by removing the insulating litter, peat, and live biomass and darkening the soil surface [12]. Fires hot enough to thaw the permafrost occurred approximately every 600 to 2,000 years on 8 black spruce/sphagnum peatlands in northern Alberta [140].
Fuels: Mosses can carry surface and ground fires, especially when dry. Aboveground biomass in peatlands where ribbed bog moss occurs is generally least in open sedge fens and greatest in coniferous swamps such as Atlantic white-cedar [141]:
Aboveground standing biomass in northern peatlands that may support ribbed bog moss. Data are means, reported in kg/ha (adapted from [141]). Peatland type Moss layer Herb layer Shrub layer Tree layer Total Location Source Open fen not measured 7,380 not applicable not applicable 7,380 central Minnesota [9] Open fen biomass not measured; ribbed bog moss frequency was 45% on moderately-wet fens 5,150 not applicable not applicable 5,150 Rocky Mts., Alberta [53] Shrubby fen 875 7,922 16,264 not applicable 25,061 southern Manitoba [95] Treed fen not measured 1,869 293 98,075 100,237 central Minnesota [98] Open bog 1,313 not measured 4,233 not applicable 5,546 southern Manitoba [95] Treed bog 927 not measured 5,015 3,998 9,940 southern Manitoba [95] Treed bog 3,200 140 4,940 30,980 39,260 northern Minnesota [55] Forested bog 2,000 not measured 1,386 43,158 46,544 southern Manitoba [95] Forested bog 3,800 220 1,025 100,730 105,775 northern Minnesota [55] Conifer swamp not measured 542 (herbs & shrubs combined) 159,406 159,948 central Minnesota [98]Ribbed bog moss and its groundlayer associates form patchy to continuous groundlayer fuels, although the ground layer may be too wet to burn in most years [141]. Ruess and others [105] describe structure of black spruce forests in interior Alaska as open, with a layer of low ericaceous shrubs and bog birch, and a "nearly continuous" ground layer of ribbed bog moss, other mosses, and lichens, especially Peltigera aphthosa and Cladonia gracilis. Compared to white spruce, black spruce forests have more widely spaced trees, deeper peat layers, and more fine crown fuels [48]. Fire-return intervals in northern spruce forests range from 50 to 100 years in western continental zones [63] to over 500 [46] years in eastern humid zones. In quaking aspen and jack pine communities near Thompson, Manitoba, ribbed bog moss dominated poorly drained quaking aspen and jack pine fens; ground cover of ribbed bog moss and associated mosses was discontinuous in both young (16-year-old) and old (155-year-old) stands. Mean leaf area index was 473 cm²/g for ribbed bog moss, the lowest of 10 mosses measured [14].
Measures of moss productivity and fuel continuity for plant communities with ribbed bog moss
Site Fuel measures Quaking aspen and jack pine communities near Thompson, Manitoba Overall bryophyte biomass was 102-228 g/m² on ribbed bog moss-dominated sites; ribbed bog moss cover was 23-43% [14]. Ribbed bog moss-dominated bog in southeastern Manitoba Mean net annual productivity of ribbed bog moss was estimated at 5.4 g/m²; annual litter decay rate estimated at 0.4 g/m². Mean ribbed bog moss biomass was 20.1 g/m²; mean ribbed bog moss cover was 1,509 cm²/m² [95]. Boreal Ecosystem Research and Monitoring Sites research area, Saskatchewan Mean ribbed bog moss productivity was 5 g/m² for the July-October 1994 growing season [4].In a survey of burned sites in the Mackenzie Valley, Northwest Territories, fuels in black spruce forests became more uniformly flammable from south to north as hardwood trees became less frequent and black spruce more frequent. Quick-drying lichens and mosses, including ribbed bog moss, also became more frequent with increasing latitude. Decay of organic material was slow, so dead fuels accumulated over long periods of time, eventually fueling extensive fires [104]. Boreal peat may build up for centuries, or even eras, on some sites [3], creating deep fuels. In Durham, England, the lowest layers of a peatland over glacial till were carbon-dated to the Pleistocene. Macrofossil ribbed bog moss leaves and stems were found in an "excellent state of preservation" [6]. On Northern Ellesmere Island, Northwest Territories, ribbed bog moss fragments dated to the Holocene occurred on a sloped peatland at peat depths of 12.5 to 13.4 feet (3.8-4.1 m) [74]. Cores from Alberta peatlands showed mean depths to mineral soil ranged from 3.6 feet (1.1 m) on sphagnum peatland to 16.4 feet (5.0 m) on peatlands dominated by vascular herbs [3].
Fire size and frequency vary widely across ribbed bog moss's range in arctic and boreal regions of North America. Peatland fires in arctic tundra and subarctic and boreal taiga, shrub, and graminoid communities are mostly small, but wildfires occasionally burn hundreds of thousands of acres. Fire-return intervals range from less than 100 to thousands of years.
In the United States, peatlands cover about 25,000 square miles (65,000 km²) in Alaska and about 26,000 square miles (68,000 km²) in the north-central and northeastern United States [141]. In Alaska and western Canada, tundra fires typically burn only 2.5 to 25 acres (1-10 ha), although some tundra fires have burned up to 247,000 acres (100,000 ha) [12]. Large wildfires are rare in Alaska's boreal black spruce-lichen taiga due to uneven fuel moisture and continuity in open and wooded mires [122]. Due to vast acreages, however, the mostly small wildfires burn considerable areas of land in most years. Zolatai and others [141] estimate that about 0.5%, or 287,000 acres (116,000), burned annually across North America's arctic and boreal zones in the 1900s. Lutz [83] estimated that from 1893 to 1939, an average of 1 million acres (405,000 ha) burned annually in Alaska's interior taiga. Foote [42] estimated that from 1940 to 1979a period when fire exclusion was practicedthe average area burned in interior Alaska ranged from 498,400 to 1.24 million acres (201,700-502,400 ha). She noted that the total number of fires increased each decade, but total area burned decreased during that time, probably due to increased ability to detect and control taiga wildfires [42]. Areas actually burned by fire may often be overestimated, however, because boreal peatland fires typically create mosaics with many unburned patches within the fire's perimeter [104].
Wooded plant communities with ribbed bog moss generally burn more often than boreal communities dominated by mosses or graminoids. Fires in old-growth spruce forests usually crown [48,62], although this aspect of fire behavior does not affect mosses as much as fire behavior on the surface and in peat layers (see Fire depth). Jasieniuk and Johnson [66] observed that fires in upland forests are about twice as common as fires on open peatlands. Fire-return intervals in northern peatlands are estimated at 120 years on bog borders and 140 years on deep peat [103]. Based on observations, aerial photos, and fire maps, Zoltai and others [141] estimated that return intervals for peat fires range from 75 to 1,000 years, depending on region and peatland type. They used estimates of peatland areas, fire-return intervals, and moisture regimes to estimate annual area and biomass burned. Across peatland types with available data, area burned was probably greatest in subarctic permafrost bogs. Area burned was least in boreal permafrost bogs with continental climates, although fires in subarctic bogs without permafrost consumed the least biomass [141].
Fire-return intervals and estimated biomass loss in northern peatlands [141] Peatland type Region and climate Peatland area (km²) Fire-return interval (years) Long-term mean area burned annually (km²) Estimated biomass burned (t) Fens subarctic 280,000 300 935 327,000 boreal, continental 144,000 300 480 168,000 boreal, humid 102,000 1,000 100 35,000 Bogs subarctic 10,000 150 65 11,000 boreal, continental 63,000 150 420 147,000 boreal, humid 100,000 800 125 22,000 Permafrost bogs subarctic 343,000 100 3,430 1,200,000 boreal, continental 4,000 150 25 26,000 boreal, humid no data no data no data no data Forested swamps subarctic no data no data no data no data boreal, continental 44,000 75 585 3,071,000 boreal, humid 51,000 200 255 1,339,000 Total 1,141,000 6,420 6,346,000Viereck and Schandelmeier [130] give a fire frequency range of 50 to 200 years for Alaska's interior taiga. A fire history study in Kluane National Park showed a mean fire-return interval of 172 years for the Park, which is mostly white spruce forest. Fire size ranged from 2.5 to 12,000 acres (1-5,000 ha). White spruce/ribbed bog moss forest occurred in wet areas of the Park [62], so the mean fire-return interval in white spruce/ribbed bog moss forest was probably longer than 172 years. The authors found estimates of past rates of spread and fire intensities "almost impossible to make". The elongated shape of large burns (>2,500 acres (1,000 ha)) suggested that large fires were driven by strong down-valley winds, while smaller burns had more variable shapes [62].
In macrofossil and charcoal analyses of peatland sites across boreal Alberta, Saskatchewan, and Manitoba, Kuhry [70] found that for the past 2,500 years, mean frequency in peatland ecosystems averaged one fire every 1,150 years. Kuhry found that wet fens were less susceptible to fires than drier sites, but charcoal evidence showed that wet fens sometimes burned. Sphagnum dominated most sites before and after fire, although ribbed bog moss was a postfire dominant on a northwestern Saskatchewan site. Fire-return intervals at the site where ribbed bog moss dominated were the shortest among all sites studied, with a mean fire-return interval of 400 years [70].
Fire depth: There are 3 basic types of peat fires: surface fires, shallow peat fires, and deep peat fires. Surface peat fires have flaming combustion, while fires burning into lower peat layers have smoldering combustion or a combination of flaming and smoldering combustion [141].
A surface peat fire burns only the standing and/or surface layers of biomass. Surface fire is the most common type of peat fire in contemporary boreal and arctic ecosystems [141]. Since surface fires leave little or no charcoal, their historical frequency is difficult to estimate. Researchers observing surface peatland fires report that surface peat fires are patchy due to discontinuous fuels and pooled surface waters [45,66,136]. Estimates of biomass consumed in these patchy surface fires range from 5,000 to 10,000 kg of standing biomass/ha for moderate-intensity surface fires to 15,000 kg of standing biomass/ha for intense surface fires burning in dry weather [34,69]. Based on climate, fuel loads, and depth to water table, arctic peatlands underlain with permafrost are most likely to burn in surface fires, followed by boreal swamps, bogs, and fens, respectively [141].
Shallow peat fires consume standing biomass and burn into top layers of underlying peat. Moisture content of surface peat determines whether underlying peat ignites and sustains combustion [141]. Smoldering combustion in shallow peat layers results from moist conditions and limited oxygen below the surface peat [70]. Weather conditions and peat-layer moisture levels are seldom dry enough to support shallow peat fires in northern wetlands. Based on frequency of charcoal layers, fire-return intervals range from 25 to 1,000 years for shallow peat fires [70]. Chistjakov and others [23] state that peatlands can ignite from "small ignition sources" at 20% to 30% moisture content and sustain combustion at levels below 235% moisture content. Maximum moisture content that sustains combustion increases greatly when burning surface fuels provide widespread, sustained ignition sources [23]. Hummocks, which are preferred ribbed bog moss habitat, often have greater ignition potentials than lower terrain because the surface peat drains and dries out more quickly on hummocks [141].
It is likely that many peat fires are mixed, burning into shallow peat layers on dry microsites or microsites with large downed woody debris, and burning only the surface layer where moss layers are moist [65]; however, fine-scale fire behavior on peatlands is poorly documented. Since moss communities often assemble by moisture gradient, more fine-scale studies of fire behavior are needed to better understand patterns of moss recovery after peat fires.
Deep peat fires are rare. Although there are anecdotal reports of fires smoldering "for years" up to 3 feet (1 m) below the peat surface, deep peat fires are documented only on areas where natural or anthropogenic disturbances lowered the water table [23,135,141]. Peatlands drained for agriculture and then burned under prescription have burned down to mineral soil [135].
The following table provides fire regime information that may be relevant to ribbed bog moss. Find further fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find FIRE REGIMES".
Fire regime information on vegetation communities in which ribbed bog moss is known to occur. For each community, fire regime characteristics are taken from the LANDFIRE Rapid Assessment Vegetation Models [76]. These vegetation models were developed by local experts using available literature, local data, and/or expert opinion as documented in the PDF file linked from the name of each Potential Natural Vegetation Group listed below. Cells are blank where information is not available in the Rapid Assessment Vegetation Model. Pacific Northwest California Southwest Great Basin Northern and Central Rockies Northern Great Plains Great Lakes Northeast South-central US Southern Appalachians Southeast Pacific Northwest Vegetation Community (Potential Natural Vegetation Group) Fire severity* Fire regime characteristics Percent of fires Mean intervalRibbed bog moss establishes on burned areas (for example, [15,16,30]). Although ribbed bog moss strategies for postfire establishment were not documented as of 2008, ribbed bog moss may establish from off-site spores [67] and/or unburned gemmae [5,25,106], paraphyses [96], and gametophyte fragments after fire (see Vegetative regeneration). Soil movement or machinery may move ribbed bog moss fragments onto burns [5,78,89]. Some researchers speculate that mosses can establish from spores stored in the substrate [16,67], so establishment from on-site spores may occur after fire.
Fires that do not burn deeply into peat may favor ribbed bog moss on many sites [16]. Although depth of burn into peat is seldom measured, it is an important factor in rate of postfire recovery of nonvascular plant species such as ribbed bog moss [141]. On Crow Lake Bog, an open sphagnum peatland in Alberta, ribbed bog moss was present on unburned plots but was not present on wildfire-burned plots in postfire year 1. The fire was mostly "severe", burning 2 inches (5 cm) or more into peat layers four times as often as it burned into only surface peat [8].
As of 2008, most fire studies of ribbed bog moss were conducted in spruce forests. Studies are also needed on the postfire response of ribbed bog moss on shrub peatlands, sedge meadows, moss mires, and other unforested wetland types.
Ribbed bog moss is most common in midsuccession after fire in spruce forests [15,30,42,70], although it also occurs in early [16] and late [15,42] postfire succession. Several studies note ribbed bog moss occurrence relatively soon after fires in forested peatlands. Ribbed bog moss, black spruce, and bog Labrador tea each attained 2% cover 4 years after a wildfire in a black spruce/bog Labrador tea community in Mackenzie Valley, Northwest Territories. No plant species had attained more than 2% cover by that time. Ribbed bog moss cover in unburned black spruce forest in Mackenzie Valley averaged 6% [104]. In a black spruce forest in northeastern Alberta, ribbed bog moss was common on burned sites and increased in frequency on both unlogged and salvage-logged burned sites during the first 2 postfire years [16].
Mean ribbed bog moss frequency (%) on wood and soil substrates after the House River wildfire in Alberta [16]Substrate
Postfire year 1 Postfire year 2 Unlogged Salvage logged Unlogged Salvage logged Burned wood 25.0 6.9 46.7 31.9 Burned soil (includes mineral and organic soils) 23.3 15.3 52.5 41.7In surveys conducted after the 1950 Porcupine Fire in northeastern Alaska, ribbed bog moss dominated 23-year-old burned black spruce sites, successionally replacing fire moss, the earliest seral species. Postfire expansion of ribbed bog moss, splendid feather moss, and turgid aulacomnium moss (Aulacomnium turgidum) was patchy. Permafrost re-formed below ground where moss patches insulated the soil (review draft by [43]). A survey taken 30 years after a wildfire in black spruce forest-tundra ecotone in northern Quebec found ribbed bog moss had 1% to 2% frequency on upland forest, lowland forest, and heath-bog birch sites [109].
Ribbed bog moss was common in early and midsuccession in a study of burned spruce communities across northwestern Canada. In surveys from north-central Saskatchewan to extreme eastern Northwest Territories, juniper hair cap moss, hairy polytrichum moss (Polytrichum piliferum), fire moss, and the liverwort Marchantia polymorpha generally dominated burns less than 10 years old; ribbed bog moss was a common component of these early-seral, nonvascular plant assemblages. After 11 to 50 postfire years, ribbed bog moss, ciliate hedwigia moss (Hedwigia ciliata), Schreber's moss, and common hair cap moss (P. commune) typically codominated with fire moss. Scotter [108] noted that ribbed bog moss and other seral mosses aided establishment of later-successional plant species by building up a litter layer on mineral soil and rocks. Ribbed bog moss was present but not typically dominant after 50 postfire years; dicranum and sphagnum mosses often dominated the ground layer of these older forests [108].
A few studies found ribbed bog moss abundance peaked in mid- to late postfire succession. In a survey of different-aged burns in black spruce forests in the Mackenzie Valley, Northwest Territories, ribbed bog moss had 2% cover on 53-year-old burns but was not present on 4-year-old or 92-year-old burns [104]. A Quebec study found ribbed bog moss cover was greatest on sites that had not experienced fire for at least 80 years [15]. A chronosequence study of postfire and postlogging succession in lodgepole pine forests of northern interior British Columbia found ribbed bog moss present in trace amounts in midsuccession (postfire years 51-100) but not in earlier or later stages [30]. In an inventory of sites in different postfire successional stages of taiga spruce forests in interior Alaska, Foote [42] found that ribbed bog moss was most common in 5- to 50-year-old black spruce-white spruce/bog birch/lichen stands.
Ribbed bog moss frequency and cover by successional stage on burned black spruce-white spruce sites in interior Alaskan taiga [42] Postfire successional stage Stand age (years) Percent frequency of ribbed bog moss (SD) Percent cover of ribbed bog moss (SD) Newly burned 0-1 0 (0) 0 (0) Moss-herb 1-5 10 (14) 1 (1) Tall shrub-sapling 5-30 19 (32) 2 (5) Dense tree 30-55 17 (26) 2 (5) Mixed hardwood-spruce 55-90 2 (3) <0.5 (1) Spruce 90-200 9 (12) 1 (2)In south-central Yukon, 2 study of a white spruce-black spruce stands that had burned 6 and 9 years previously found ribbed bog moss was an indicator species for sites having long fire-free intervals (80-250 years without fire). However, ribbed bog moss was found on 1 plot with short (26-45 years) fire-free intervals [67].
As of 2008, only a few fire studies conducted in the contiguous United States provided data on ribbed bog moss's postfire occurrence. Ribbed bog moss had similar frequencies in burned (51.7%) and logged (50.0%) stands in northern Minnesota. Data were collected in quaking aspen, jack pine, and black spruces forests ranging from 25 to 100 years old; frequency data were pooled across forest ages and types [97]. Ribbed bog moss had 1.7% cover and 68% frequency 94 years after a wildfire in a catberry-highbush blueberry (Ilex mucronata-Vaccinium corymbosum) bog in central New York. Sphagnum mosses dominated the ground layer [77].
Ribbed bog moss coverage was similar (≤1%) on burned mineral soil and unburned forest floor plots, but its frequency was greater unburned forest floor plots (13%) compared to burned plots (5%) after multiple treatments in east-central British Columbia. The site was a hybrid spruce/devil's club community that was logged, slashburned, and replanted with conifers prior to postfire moss and lichen inventories in postfire year 4. Postfire coverage of over 100 vascular plants, mosses, liverworts, and lichens was inventoried for this study. Prefire coverage was also measured for vascular plants. For details on the fire prescription and plant and lichen species responses after fire, see the Research Paper by Hamilton [57].
Ribbed bog moss regenerates sexually and vegetatively.
Gametophyte dispersal and establishment: A spore is the first growth stage of a developing gametophyte [138]. When the spore capsule matures, ribbed bog moss's calyptra splits along the side, exposing spores [133]. 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 [8,67,138]. When air is moist, the teeth bend inward, holding the spores within the capsule [138]. 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 [138]. 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 [10]. Bernhard and Renzaglia [10,11] provide details of cellular development of ribbed bog moss sperm cells. 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 [138].
Spore banking: Ribbed bog moss may germinate from spores stored in the substrate [67,102], but banked spores are probably less important to ribbed bog moss regeneration than freshly-dispersed spores. Ross-Davis and Frego [102] 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.
Breeding system: Ribbed bog moss is dioecious [33,133]
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 [138].
Vegetative regeneration: Ribbed bog moss reproduces asexually from specialized gametophyte tissues and from plant breakage. It reproduces frequently from gemmae [5,25,106]. 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 [96]. Ribbed bog moss establishes readily when chunks of ribbed bog moss shoots are moved to new sites by soil movement or transplanting [5,78,89]. Ribbed bog moss is apparently competitive in its ability to establish from stem chunks [5,78]. 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 [78].
Figure courtesy of Brooklyn Botanic Gardens
In Great Britain, sphagnum mosses regenerated from both spores and stem fragments extracted from peat cores [24]. Ribbed bog moss was not present in core samples; however, it may have similar ability to regenerate from peat-stored gametophyte tissues.
Growth: Ribbed bog moss growth is "robust" [33,114]. 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 [5]. 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 [4]. Productivity measures of ribbed bog moss are provided in Fuels.
Ribbed bog moss occurs in all stages of succession on open and forested peatlands, tolerating full sunlight [80,99] and moderate shade [119] conditions. In the Boreal Ecosystem Research and Monitoring Sites study area, ribbed bog moss occurs in stands with a "wide range" of canopy closures [4]. Ribbed bog moss tends to decline in closed-canopy forests, however [14,31].
Mire succession: The transition from pond or lake to bog is influenced partially by physical factorsincluding water chemistry, hydrology, and climateand partially by vegetational succession. Mires transition from rich fens to poor fens to bogs [132]. Water chemistryespecially acidificationoften triggers a rapid transition from rich to poor fen [71,131]. Rates of oligotrophication and peat buildup also influence transition rates; these factors are largely mediated by the vegetation [3]. Succession from a pond or marsh to a peatland typically takes thousands of years in northern ecosystems [3,71,123].
There are 2 primary ways that peatlands develop vegetatively: mosses either grow over open water and slowly fill in a site (terrestrialization), or mosses blanket open land and prevent water from draining (paludification) [128]. Many studies document ribbed bog moss participation in terrestrialization (for example, [3,27,71,89]). Ribbed bog moss is likely also involved in paludification; however, literature documenting ribbed bog moss presence on sites undergoing paludification was not found in this literature review. A chronosequence study of terrestrialization in central Alberta showed peat first began accumulating over open water approximately 7,000 years BP, probably during a period of climatic cooling [3]. In boreal western Canada, the oldest bogs dated from 5,020 to 7,870 years BP, with the most northerly bogs being the oldest. The youngest peatlands were on southern edges of the spruce/moss peatland ecotones; young bogs dated from 3,100 to 4,670 years BP. Although southern peatlands are typically younger, the fen-to-bog transition has proceeded more slowly in southern peatlands (>2,000 years to transition from young fen to bog) than in northern peatlands (<1,500 years to transition) [71]. In boreal western Canada, ribbed bog moss was characteristic of mires transitioning from open rich fens dominated by Drepanocladus spp. mosses to poor, spruce-dominated fens. The researchers estimated the transition time from open rich fen to spruce fen ranged from 50 to 350 years. Fens with water pH ranging from 6.67 to 6.86, indicating they were relatively young, were dominated by the mosses Drepanocladus spp. and Campylium stellatum. Ribbed bog moss dominated a moderate-rich fen with a water pH of 5.70, indicating that the fen was older than the fens with higher pH values. Sphagnum mosses generally dominated bogs (water pH <5.00) [71].
Ribbed bog moss occurs in all stages of mire succession except open ponds. On Isle Royal on Lake Superior, ribbed bog moss forms mats on rock pools near the shoreline. Ribbed bog moss, common hair cap moss (Polytrichum commune), and roots and rhizomes of vascular plants eventually fill in the pools [27]. In a poor fen in boreal Alberta, knight's-plume moss (Ptilium crista-castrensis) and Schreber's moss (Pleurozium schreberi) apparently facilitated establishment of ribbed bog moss [89]. During dry periods, ribbed bog moss may succeed sphagnum mosses in the western Great Lakes-St Lawrence region [99].
Swinehart and Parker [123] found ribbed bog moss occurred in late mire succession in a study on the Little Chapman Bog in Kosciusko County, Indiana. Development began approximately 3,500 years BP within an old embayment of Little Chapman Lake. The embayment was first vegetated with submerged aquatic plants, followed by a transition phase where mat-forming aquatic plants such as three-cornered meesia moss (Meesia triquetra) grew on the water surface and bulrushes (Scirpus validus, S. acutus) colonized pond edges. Fen plants such as sedges and cranberry (Vaccinium macrocarpon) were present around 1,850 years BP. The transition from fen to bog occurred quickly, from the 1920s to the 1950s. Ribbed bog moss and sphagnum mosses dominated the vegetation in the 1990s, when the wetland had fully transitioned to a bog [123].
Shrubland and forest succession: Shrubs or mosses dominate arctic bogs in late succession [141], while conifers eventually dominate the overstory of many boreal bogs [26,71]. Mire succession proceeded as follows on sites in central Minnesota [26]:
open pond → floating mat → moss-heath → tamarack-spruce → mature spruce → Atlantic white-cedar bogRibbed bog moss generally dominated the moss-heath and tamarack-spruce stages (35-70% frequency), persisted in mature spruce forests (7.5-60% frequency), and declined in late-seral stages (25-30% frequency) [26].
Although it may require hundreds to thousands of years for woody plants to initially establish in such pond-to-boreal forest sequences [123], once woody plants have established, reforestation may take only a few decades following stand-replacing events such as fire. Ribbed bog moss is most common in early- to midseral secondary forest succession [26]. Across British Columbia and Alberta, ribbed bog moss occurred on open to closed sites (5-90% overstory cover) but occurred most often in open forests with 5% to 15% overstory cover [50]. In a mixed quaking aspen-paper birch-balsam fir forest in east-central Alberta, ribbed bog moss grew in young (23-26 years) and mature (51-63 years) forests but was not present in old growth (122-146 years) [31]. Ribbed bog moss may be frequent in some late-seral spruce forests, however [119], and is occasionally noted in old growth [133]. Ribbed bog moss occurred on the floor of a 150-year-old white spruce/bog birch forest in Yukon [21] and was a groundlayer dominant in 200-year-old black spruce/littletree willow (Salix arbusculoides)/bog Labrador tea boreal forest in the Northwest Territories [37]. Ribbed bog moss is noted in late-successional, closed-canopy white spruce forests of northern British Columbia [133] and Alberta. In late-successional white spruce-black spruce and balsam fir-Douglas-fir forests in northwestern Alberta, ribbed bog moss showed microsite preferences for "disturbed" substrates. Ribbed bog moss frequency was greatest (44%) on disturbed microsites on the forest floor, while ribbed bog moss frequency was low (2%) on undisturbed microsites [86].
Disturbed sites: Grime [56] classified mosses as "ruderals and stress tolerators", and ribbed bog moss seems to follow the general pattern of tolerating disturbances. Several studies note ribbed bog moss presence on disturbed sites [22,61,78,86]; however, ribbed bog moss may not occur for several decades after disturbance on some sites [19]. Based on laboratory studies, Li and Vitt [78] concluded that ribbed bog moss regenerates quickly on disturbed microsites. Field studies also document ribbed bog moss presence on disturbed sites. An inventory of 14- to 38-year-old coal mine spoils in Iowa found ribbed bog moss pioneered on coal mine seeps [22]. In a study of succession 48 years after the CANOL Pipeline was constructed through bog birch-heath tundra in the Northwest Territories, ribbed bog moss was present in both denuded vehicle track and undisturbed areas [61]. Near Mayo, Yukon, ribbed bog moss was most common on thaw-sensitive permafrost 43 years after soil slumpage from thawing [19].
Ribbed bog moss cover in a successional sequence on thaw-slump sites in west-central Yukon [19] Community dominant Years after slumpage ribbed bog moss cover (%) Funaria moss (Funaria hygrometrica) 1-2 0 Marsh fleabane (Senecio congestus) 2-5 0 Field horsetail/bog birch (Equisetum arvense/Salix glauca) 6-9 trace Field horsetail 6-15 0 Grayleaf willow (Salix glauca)/bog birch 12-15 <5 Bog birch/white spruce 43 25-50 White spruce, mature forest ≥44 5-25Logging: Ribbed bog moss generally tolerates tree harvest. In a New Brunswick study, ribbed bog moss cover and frequency were not significantly different among unlogged red spruce-balsam fir forest, clearcuts, and machinery tracks 4 years after logging [39]. Logging that opens the canopies of late-successional forests may favor ribbed bog moss. In a study near Thompson, Manitoba, ribbed bog moss dominated poorly drained quaking aspen and jack pine communities in early- to late-successional stages following logging. Mean ribbed bog moss coverage ranged from 33.5% 16 years after harvest to 23.3% cover 155 years after harvest. On well-drained sites, ribbed bog moss was dominant only in early succession, showing 31% coverage sixteen years after harvest, 4% forty-one years after harvest, and 0% seventy-five and 155 years after harvest [14]. With a mean frequency of 80%, ribbed bog moss was common in 6- to 12-year-old lodgepole pine clearcuts in central Alberta. It was also common in mature lodgepole pine forests, although ribbed bog moss cover (1-4%) was less than that of feather mosses (4-12%) in mature lodgepole pine forests [29].
In a late 1980s study in northeastern Ontario and western Quebec, ribbed bog moss was common in black spruce lowlands on both logged and unlogged sites. On logged sites, it was abundant in both early and late stages of postlogging succession. The study sites (n=122) had been winter-logged with horses from 1940 until the early 1960s, when winter skidder logging replaced horse logging and increased the frequency and level of disturbance of winter logging. In addition to winter skidder logging, summer skidder logging started in the 1970s and continued through the late 1980s; summer-skidder logging disturbed the forest substrate the most. However, ribbed bog moss showed high abundance relative to other plant species (mean frequency >45%) on all logging treatments and on control sites. Ribbed bog moss had similar coverages (1.3-1.7%) across all logging treatments, but its cover was less on unlogged sites (0.1-0.3%) [18].
Logging may result in ribbed bog moss decline. In lodgepole pine forests of northern interior British Columbia, ribbed bog moss was not present approximately 30 years after logging, although it was present on unlogged sites and on sites burned 51 to 100 years prior to the study [30]. Factors determining rate of ribbed bog moss recovery after logging are not well understood.
Fire: See Plant Response to Fire.
Aulacomnium palustre, the bog groove-moss[1] 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,[2] subboreal,[3] and boreal[4] 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.
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.[5] 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.
Mosses have 2 phases in their life cycle: the gametophyte (n) and sporophyte (2n) generations. Each generation is morphologically distinct.
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 1 to 4 inches (3–9 cm) 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 0.6 inch (1.5 cm) 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 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 1.8 inches (4.5 cm) 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.
Ribbed bog moss regenerates sexually and vegetatively.
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.
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.[6]
Ribbed bog moss is dioecious.
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.
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.
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.
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.
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 20 to 26 inches (50–65 cm) below ground, and there is 30% to 60% black spruce and/or tamarack cover.
Ribbed bog moss is primarily a groundlayer 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 38 to 102 inches (15–40 cm) 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.
Ribbed bog moss grows on peat and other organic soil layers more often than on downed bark or wood, but is reported growing on woody debris or other dead wood in a few locations. In northern British Columbia, ribbed bog moss substrates included disturbed forest floors, logs, and stumps at 44%, 13%, and 3% frequencies, respectively. Ribbed bog moss was found on downed woody debris in a mixed quaking aspen-paper birch-balsam fir (Populus tremuloides-Betula papyrifera-Abies balsamifera) forest in east-central Alberta and on stumps in a mixed-hardwood forest in Wisconsin. Ribbed bog moss rarely grows on standing live or dead wood.
Ribbed bog moss showed broad substrate tolerances in a greenhouse common pot study in Scotland. Ribbed bog moss vegetative propagules were sown with propagules of 6 other mosses to test substrate preferences. After 1 year, ribbed bog moss abundance was similar on heather (Calluna vulgaris) litter, European white birch (Betula pendula) litter, dead shrub litter, Scots pine (Pinus sylvestris) needles, sand, and sphagnum peat substrates. To test particle-size microsite preferences on peat substrates, the peat was broken into various fragment sizes from minute to large (<0.25 inch to>2 inches (0.63–5 cm)). Ribbed bog moss grew on peat of all particle sizes but was most frequent on small (0.5-1 inch (1.25-2.5 cm)) peat particles.
The pH of water, peat, and/or soil is usually acidic to neutral in mires with ribbed bog moss, although ribbed bog moss tolerates mildly alkaline conditions. For example, ribbed bog moss grows in extremely acidic peatlands overlying permafrost in spruce taiga of Alaska but also grows in calcareous bogs in Birds Hill Provincial Park. In Minnesota, ribbed bog moss is reported from bogs ranging from 5.0 to 7.3 in pH. A survey of bryophytes on peatlands across Alberta's Mackenzie River basin found ribbed bog moss was abundant on sites ranging from 4.5 to 7.5 in pH.
Mires are classified on pH and mineral gradients from extreme-poor (very strongly acid and low in calcium and magnesium) to extreme-rich (neutral to alkaline and high in calcium and magnesium). Fens are richer than bogs. Ribbed bog moss occurs in poor and rich mires. On mires across British Columbia and Alberta, ribbed bog moss grows in mires with broad ranges of water pH and electrical conductivity, but is most common on strongly acidic peatlands (water pH <5.5) with moderate calcium and magnesium levels (<200 μS/cm**). Ribbed bog moss also grows in moderate-rich fens with higher pH and electrical conductivity values. In a peat-core study in central Alberta, macrofossil ribbed bog moss was an indicator species of moderate-rich fens; ribbed bog moss occurred most often on mires that were moderately acidic (x pH=6.0) and had low electrical conductivity (x=125 μS/cm) and moderately high water tables (x= 8.7 inches (22 cm) deep). In a study of alpine mires in Italy, ribbed bog moss was intermediate in mire pH and mineral content compared to associated nonvascular and vascular plant species, occurring on both poor and rich mires. All associated mosses had narrower pH and mineral tolerances than ribbed bog moss. Gignac provides information on ribbed bog moss habitats in British Columbia and Alberta including ranges in pH, electrical conductivity, relative depth to the water table, and relative overstory cover.
Field observations and laboratory experiments suggest that ribbed bog moss has broad tolerance and may be relatively insensitive to macronutrient concentrations. On the Svalbard archipelago in Norway, ribbed bog moss grows on small "bird islands" where eiders, Arctic terns, and other migratory birds nest offshore of the main island, Spitsbergen. Nitrogen levels on the bird islands are very high. On Spitsbergen Island, however, ribbed bog moss grows on dry hummocks and moist hummock edges, both of which have low nitrogen levels but probably provide moisture levels that favor ribbed bog moss. In a laboratory experiment, nitrogen fertilizer initially slowed ribbed bog moss growth rate, but growth rates of ribbed bog moss with and without nitrogen were similar at the end of 125 days. Addition of phosphorus had no effect on ribbed bog moss growth.
Ribbed bog moss is listed as an indicator species of nitrogen-medium soils in British Columbia.
Tundra and taiga areas where ribbed bog moss grows are generally flat to gently sloped, but local relief creates drainage patterns that often result in distinct moss assemblages. Site geology, including topography, bedrock composition, catchment hydrology, and basin bathymetry, affects wetland drainage and partially controls rates of transition from open water to bog. Ribbed bog moss is common on hummocks, which tend to dry out faster than adjacent lowlands. In British Columbia and Alberta, ribbed bog moss often dominates hummock tops that are surrounded by sphagnum peatlands. Although ribbed bog moss generally attains greatest coverage on hummock tops, it sometimes forms lawns and strings in low areas. In Labrador, tufted bulrush-mountain fly honeysuckle/ribbed bog moss associations occur on low strings of consolidated peat and on elevated peatlands. The low strings lie 38 to 76 inches (15–30 cm) above the water table and lack erosion patterns.
In Kluane National Park, Yukon, the white spruce/ribbed bog moss forest community occurs on poorly drained east- and north-facing slopes.
There are few reports of ribbed bog moss's elevational tolerances. Ribbed bog moss is reported from 1,600 to 5,700 feet (500-1,750 m) in west-central Alberta and at 827 feet (252 m) in Kosciucko County, Indiana. In subalpine and alpine communities of the North Cascade Range in Washington and British Columbia, ribbed bog moss occurs on high-elevation (>7,380 feet (2,250 m)) sites that remain snow-free most of the year.
Ribbed bog moss occurs in arctic, subarctic, boreal, and subboreal zones with cold meso-thermal, oceanic, continental, or cold-humid climates. It is more common in arctic, subarctic, and boreal than subboreal zones. A survey of bryophytes on peatlands across Alberta's Mackenzie River basin found optimal ribbed bog moss growth occurred on sites with annual temperatures ranging from 20 to 32 °F (-4 to 0 °C). In interior arctic, subarctic, and boreal zones, climate is strongly continental in the west, becoming more humid to the east. Climate shift from continental to humid generally occurs near Hudson Bay and Lake Superior. In a study of moss habitats across British Columbia, Alberta, and Manitoba, ribbed bog moss was an indicator species for continentality of climate: it was the only moss common to all continental peatlands surveyed. On sites from coastal British Columbia to central Alberta, ribbed bog moss was most common on subcontinental sites (intermediate between coastal and continental climates). Ribbed bog moss was intermediate on gradients ranking breadth of moss habitat niches. Climate factors evaluated included length of growing season, amount of precipitation during the growing season, temperature, and aridity. Feather mosses (Hylocomiaceae) and sphagnum mosses generally had wider niches and dominated more sites than ribbed bog moss. Ribbed bog moss's rarity on all but cold sites in the lower 48 states suggests that ribbed bog moss does not tolerate long periods of warm weather. In a geothermal meadow on Queen Charlotte Island, British Columbia, ribbed bog moss was absent from sites where nearby thermal pools raised local soil temperatures above 86 °F (30 °C).
Ribbed bog moss provides few known direct benefits to wildlife or livestock. Mosses in general are low in carbohydrates, proteins, and fats compared to vascular plants, and animals seldom graze them. Caribou may eat mosses when little other forage is available. Wildlife seeking cover probably avoid open areas dominated by ribbed bog moss or other low vegetation. In Wood Buffalo National Park, Alberta, aerial photos identified areas dominated by ribbed bog moss, bog Labrador tea, and/or Bebb willow as indicators of nonnesting habitat for whooping cranes.
American robins at the Mountain Lake Biological Station, Virginia, used ribbed bog moss as nest material.
Northern mires provide habitat for a variety of invertebrates including worms, crustaceans, arachnids, and insects, particularly mosquitoes, midges, and other flies.
Chunks from ribbed bog moss lawns can be transplanted onto disturbed sites. In Minnesota, moss plugs used in restoration projects on old peat mines are harvested from nearby unmined sites in spring, before the ground thaws. Although ribbed bog moss is not often used for restoration, it could be a valuable addition to restoration projects. Foote classified ribbed bog moss communities along the Alaskan Highway in Yukon as having "high site sensitivity", with moderate potential for erosion.[7] Black spruce/ribbed bog moss communities on the Alaskan Pipeline are rated "sensitive to highly sensitive" to erosion and disturbance.
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, subboreal, and boreal 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.
