Sphagnum | |
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Sphagnum flexuosum | |
Scientific classification ![]() | |
Kingdom: | Plantae |
Division: | Bryophyta |
Class: | Sphagnopsida |
Order: | Sphagnales |
Family: | Sphagnaceae |
Genus: | Sphagnum L. |
Species | |
Synonyms [1] | |
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Sphagnum is a genus of approximately 380 accepted species [2] [3] of mosses, commonly known as sphagnum moss, also bog moss and quacker moss (although that term is also sometimes used for peat). Accumulations of Sphagnum can store water, since both living and dead plants can hold large quantities of water inside their cells; plants may hold 16 to 26 times as much water as their dry weight, depending on the species. [4] The empty cells help retain water in drier conditions.
As Sphagnum moss grows, it can slowly spread into drier conditions, forming larger mires, both raised bogs and blanket bogs. [5] Thus, Sphagnum can influence the composition of such habitats, with some describing Sphagnum as 'habitat manipulators'.[ citation needed ] These peat accumulations then provide habitat for a wide array of peatland plants, including sedges and ericaceous shrubs, as well as orchids and carnivorous plants. [6] [7]
Sphagnum and the peat formed from it do not decay readily because of the phenolic compounds embedded in the moss's cell walls. In addition, bogs, like all wetlands, develop anaerobic soil conditions, which produces slower anaerobic decay rather than aerobic microbial action. Peat moss can also acidify its surroundings by taking up cations, such as calcium and magnesium, and releasing hydrogen ions.
Under the right conditions, peat can accumulate to a depth of many meters. Different species of Sphagnum have different tolerance limits for flooding and pH, and any one peatland may have a number of different Sphagnum species. [8] [6]
An individual Sphagnum plant consists of a main stem, with tightly arranged clusters of branch fascicles usually consisting of two or three spreading branches and two to four hanging branches. The top of the plant (capitulum) has compact clusters of young branches that give the plant its characteristic tuft-like appearance. Along the stem are scattered leaves of various shapes, named stem leaves; the shape varies according to species.
Sphagnum has a distinctive cellular structure. The stem portion consists of two important sections. The pith which is the site of food production and storage, and the cortical layer which serves to absorb water and protect the pith. Mosses have no vascular system to move water and nutrients around the plant. Thus tissues are thin and usually one cell thick to allow them to diffuse easily. Sphagnum mosses have two distinct cell types. There are small, green, living cells with chlorophyll (chlorophyllose cells) that produce food for the plant. Additionally there are larger hyaline or retort cells that are barrel shaped and have a pore at one end to allow for water absorption and improved water-holding capacity. These unique cells help Sphagnum to retain water during prolonged UV exposure. [9]
Sphagnum, like all other land plants, has an alternation of generations; like other bryophytes, the haploid gametophyte generation is dominant and persistent. Unlike other mosses, the long-lived gametophytes do not rely upon rhizoids to assist in water uptake. [4]
Sphagnum species can be unisexual (male or female, dioecious) or bisexual (male and female gametes produced from the same plant; monoecious); In North America, 80% of Sphagnum species are unisexual. [10]
Gametophytes have substantial asexual reproduction by fragmentation, producing much of the living material in sphagnum peatlands. [11]
Swimming sperm fertilize eggs contained in archegonia that remain attached to the female gametophyte. The sporophyte is relatively short-lived, and consists almost entirely of a shiny green, spherical spore capsule that becomes black with spores. Sporophytes are raised on stalks to facilitate spore dispersal, but unlike other mosses, Sphagnum stalks are produced by the maternal gametophyte. Tetrahedral haploid spores are produced in the sporophyte by meiosis, which are then dispersed when the capsule explosively discharges its cap, called an operculum, and shoots the spores some distance. The spores germinate to produce minute protonemae, which start as filaments, can become thalloid, and can produce a few rhizoids. Soon afterwards, the protonema develops buds and these differentiate into its characteristic, erect, leafy, branched gametophyte with chlorophyllose cells and hyaline cells. [12]
Carpets of living Sphagnum may be attacked by various fungi, and one fungus that is also a mushroom, Sphagnurus paluster , produces conspicuous dead patches. When this fungus and other agarics attack the protonema, Sphagnum is induced to produce nonphotosynthetic gemmae that can survive the fungal attack and months later germinate to produce new protonema and leafy gametophytes. [13]
Peat moss can be distinguished from other moss species by its unique branch clusters. The plant and stem color, the shape of the branch and stem leaves, and the shape of the green cells are all characteristics used to identify peat moss to species. Sphagnum taxonomy has been very contentious since the early 1900s; most species require microscopic dissection to be identified. In the field, most Sphagnum species can be identified to one of four major sections of the genus—classification and descriptions follow Andrus 2007 (Flora North America): [10]
The reciprocal monophyly of these sections and two other minor ones (Rigida and Squarrosa) has been clarified using molecular phylogenetics. [14] All but two species normally identified as Sphagnum reside in one clade; two other species have recently been separated into new families within the Sphagnales reflecting an ancestral relationship with the Tasmanian endemic Ambuchanania and long phylogenetic distance to the rest of Sphagnum. [15] Within main clade of Sphagnum, phylogenetic distance is relatively short, and molecular dating methods suggest nearly all current Sphagnum species are descended from a radiation that occurred just 14 million years ago. [16]
Sphagnum mosses occur mainly in the Northern Hemisphere in peat bogs, conifer forests, and moist tundra areas. Their northernmost populations lie in the archipelago of Svalbard, Arctic Norway, at 81° N. [17]
In the Southern Hemisphere, the largest peat areas are in southern Chile and Argentina, part of the vast Magellanic moorland (circa 44,000 square km; 17,000 sq. mi.). [18] Peat areas are also found in New Zealand and Tasmania. In the Southern Hemisphere, however, peat landscapes may contain many moss species other than Sphagnum. Sphagnum species are also reported from "dripping rocks" in mountainous, subtropical Brazil. [19]
As with many other mosses, Sphagnum species disperse spores through the wind. The tops of spore capsules are only about 1 cm (1⁄2") above ground, and where wind is weak. As the spherical spore capsule dries, the operculum is forced off, followed by a cloud of spores. The exact mechanism has traditionally attributed to a "pop gun" method using air compressed in the capsule, reaching a maximum velocity of 3.6 meters (12 feet) per second, [20] but alternative mechanisms have been recently proposed. [21] High-speed photography has shown vortex rings are created during the discharge, which enable the spores to reach a height of 10 to 20 cm (3.9 to 7.9 in), further than would be expected by ballistics alone. The acceleration of the spores is about 36,000g. [22] [23] Spores are extremely important in establishment of new populations in disturbed habitats and on islands. [24]
Human activities like slash-and-burn and cattle grazing are believed to promote the growth and expansion of Sphagnum moss. Oceanic islands such as the Faroe Islands, the Galápagos or the Azores have recorded a significant increase in their Sphagnum populations after human settlement. [25] [26]
Decayed, dried sphagnum moss has the name of peat or peat moss. This is used as a soil conditioner which increases the soil's capacity to hold water and nutrients by increasing capillary forces and cation exchange capacity – uses that are particularly useful in gardening. This is often desired when dealing with very sandy soil, or plants that need increased or steady moisture content to flourish. A distinction is sometimes made between sphagnum moss, the live moss growing on top of a peat bog, and 'sphagnum peat moss' (North American usage) or 'sphagnum peat' (British usage), the latter being the slowly decaying matter underneath. [27]
Dried sphagnum moss is used in northern Arctic regions as an insulating material.[ citation needed ]
Anaerobic acidic sphagnum bogs have low rates of decay, and hence preserve plant fragments and pollen to allow reconstruction of past environments. [7] They even preserve human bodies for millennia; examples of these preserved specimens are Tollund Man, Haraldskær Woman, Clonycavan Man and Lindow Man. Such bogs can also preserve human hair and clothing, one of the most noteworthy examples being Egtved Girl, Denmark. Because of the acidity of peat, however, bones are dissolved rather than preserved. These bogs have also been used to preserve food. [28] Up to 2000-year-old containers of butter or lard have been found. [29]
Sphagnum moss has been used for centuries as a dressing for wounds, including through World War I. [4] [30] Botanist John William Hotson's paper, Sphagnum as a surgical dressing, published in Science in 1918, was instrumental in the acceptance of Sphagnum moss use as a medical dressing in place of cotton. [31] [32] Preparations using Sphagnum such as Sphagnol soap have been used for various skin conditions including acne, ringworm, and eczema. The soap was used by the British Red Cross during both World Wars to treat facial wounds and trench sores. [33]
Since it is absorptive and extremely acidic, it inhibits growth of bacteria and fungi, so it is used for shipping seeds and live plants.[ citation needed ]
Peat moss is used to dispose of the clarified liquid output (effluent) from septic tanks in areas that lack the proper conditions for ordinary disposal means. It is also used as an environmentally friendly alternative to chlorine in swimming pool sanitation. [34] The moss inhibits the growth of microbes and reduces the need for chlorine in swimming pools. [35]
In Finland, peat mosses have been used to make bread during famines. [36]
In China, Japan and Korea, long strand dried sphagnum moss is traditionally used as a potting medium for cultivating Vanda falcata orchids. [37]
Several of the world's largest wetlands are sphagnum-dominated bogs, including the West Siberian Lowland, the Hudson Bay Lowland and the Mackenzie River Valley. These areas provide habitat for common and rare species. They also store large amounts of carbon, which helps reduce global warming. [38]
According to an article written in 2013, the U.S. got up to 80% of sphagnum peat moss it uses from Canada. At that time, in Canada, the peat bog mass harvested each year was roughly 1/60th of the peat mass that annually accumulated. About 0.02% of the 1.1 million km2 (420,000 sq mi) of Canadian peat bog are used for peat moss mining. [39] Some efforts are being made to restore peat bogs after peat mining, and some debate exists as to whether the peat bogs can be restored to their premining condition and how long the process takes. "The North American Wetlands Conservation Council estimates that harvested peatlands can be restored to 'ecologically balanced systems' within five to 20 years after peat harvesting." Some wetlands scientists assert that "a managed bog bears little resemblance to a natural one. Like tree farms, these peatlands tend toward monoculture, lacking the biodiversity of an unharvested bog." [40]
PittMoss, a peat moss alternative made from recycled newspaper, has emerged as a sustainable substitute in growing media. [41] Coir has also been touted as a sustainable alternative to peat moss in growing media. [42] Another peat moss alternative is manufactured in California from sustainably harvested redwood fiber. Semi-open cell polyurethane materials available in flaked and sheet stock are also finding application as sphagnum replacements with typical usage in green wall and roof garden substrates. [43]
In the 2010s, Sphagnum peat in Chile has begun to be harvested at a large scale for export to countries like Japan, South Korea, Taiwan and the United States. Sphagnum’s ability to absorb excess water and release it during dry months means that overexploitation may threaten the water supply in the fjords and channels of Chile. [44] Extraction of Sphagnum in Chile is regulated by law since 2 August 2018. [45] Since 2018, Chilean law allows for the manual extraction of Sphagnum using only pitchforks or similar tools as an aid. [46] In a given designated harvesting area (polygon) at least 30% of Sphagnum coverage has to be left unharvested. [46] Harvested Sphagnum fibers may not exceed 15 cm (5.9 in) in length and the remaining Sphagnum after harvest may never have a length less than 5 cm (2.0 in) over the water table. [46] In the regions of Los Ríos (40°S) and Los Lagos (41–43°S) the same plots may be harvested after 12 years, while further south in Aysén (44–48°S) and Magallanes (49–56°S) 85 years have to pass before the same area can be harvested again. [46]
Harvesting aside, bogs where Sphagnum grows have also come under threat by the development of wind farms in cool humid areas such as the Cordillera del Piuchén where the San Pedro Wind Farm was constructed in the 2010s. [47] The construction of each wind turbine usually implies the removal of vegetation and the alteration of the soil, changing by the way also of the local hydrology. [47]
Europe has a long history of the exploitation of peatlands. The Netherlands, for example, once had large areas of peatland, both fen and bog. Between 100 AD and the present, they were drained and converted to agricultural land. [7] : Fig. 14.2 The English broadlands have small lakes that originated as peat mines. [48] More than 90% of the bogs in England have been damaged or destroyed. [49] [50] A handful of bogs has been preserved through government buyouts of peat-mining interests. [51] Over longer time scales, however, some parts of England, Ireland, Scotland, and Wales have seen expansion of bogs, particularly blanket bogs, in response to deforestation and abandonment of agricultural land. [7] : Fig. 11.8
New Zealand has, like other parts of the world, lost large areas of peatland. The latest estimates for wetland loss in New Zealand are 90% over 150 years. [52] In some cases, better care is taken during the harvesting of Sphagnum to ensure enough moss is remaining to allow regrowth. An 8-year cycle is suggested, but some sites require a longer cycle of 11 to 32 years for full recovery of biomass, depending on factors including whether reseeding is done, the light intensity, and the water table. [53] This "farming" is based on a sustainable management program approved by New Zealand's Department of Conservation; it ensures the regeneration of the moss, while protecting the wildlife and the environment. Most harvesting in New Zealand swamps is done only using pitchforks without the use of heavy machinery. During transportation, helicopters are commonly employed to transfer the newly harvested moss from the swamp to the nearest road.[ citation needed ]
A gametophyte is one of the two alternating multicellular phases in the life cycles of plants and algae. It is a haploid multicellular organism that develops from a haploid spore that has one set of chromosomes. The gametophyte is the sexual phase in the life cycle of plants and algae. It develops sex organs that produce gametes, haploid sex cells that participate in fertilization to form a diploid zygote which has a double set of chromosomes. Cell division of the zygote results in a new diploid multicellular organism, the second stage in the life cycle known as the sporophyte. The sporophyte can produce haploid spores by meiosis that on germination produce a new generation of gametophytes.
Peat is an accumulation of partially decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, moors, or muskegs. Sphagnum moss, also called peat moss, is one of the most common components in peat, although many other plants can contribute. The biological features of sphagnum mosses act to create a habitat aiding peat formation, a phenomenon termed 'habitat manipulation'. Soils consisting primarily of peat are known as histosols. Peat forms in wetland conditions, where flooding or stagnant water obstructs the flow of oxygen from the atmosphere, slowing the rate of decomposition. Peat properties such as organic matter content and saturated hydraulic conductivity can exhibit high spatial heterogeneity.
A bog or bogland is a wetland that accumulates peat as a deposit of dead plant materials – often mosses, typically sphagnum moss. It is one of the four main types of wetlands. Other names for bogs include mire, mosses, quagmire, and muskeg; alkaline mires are called fens. A bayhead is another type of bog found in the forest of the Gulf Coast states in the United States. They are often covered in heath or heather shrubs rooted in the sphagnum moss and peat. The gradual accumulation of decayed plant material in a bog functions as a carbon sink.
Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophytasensu stricto. Bryophyta may also refer to the parent group bryophytes, which comprise liverworts, mosses, and hornworts. Mosses typically form dense green clumps or mats, often in damp or shady locations. The individual plants are usually composed of simple leaves that are generally only one cell thick, attached to a stem that may be branched or unbranched and has only a limited role in conducting water and nutrients. Although some species have conducting tissues, these are generally poorly developed and structurally different from similar tissue found in vascular plants. Mosses do not have seeds and after fertilisation develop sporophytes with unbranched stalks topped with single capsules containing spores. They are typically 0.2–10 cm (0.1–3.9 in) tall, though some species are much larger. Dawsonia, the tallest moss in the world, can grow to 50 cm (20 in) in height. There are approximately 12,000 species.
Bryophytes are a group of land plants, sometimes treated as a taxonomic division, that contains three groups of non-vascular land plants (embryophytes): the liverworts, hornworts, and mosses. In the strict sense, Bryophyta consists of the mosses only. Bryophytes are characteristically limited in size and prefer moist habitats although they can survive in drier environments. The bryophytes consist of about 20,000 plant species. Bryophytes produce enclosed reproductive structures, but they do not produce flowers or seeds. They reproduce sexually by spores and asexually by fragmentation or the production of gemmae. Though bryophytes were considered a paraphyletic group in recent years, almost all of the most recent phylogenetic evidence supports the monophyly of this group, as originally classified by Wilhelm Schimper in 1879. The term bryophyte comes from Ancient Greek βρύον (brúon) 'tree moss, liverwort', and φυτόν (phutón) 'plant'.
The Marchantiophyta are a division of non-vascular land plants commonly referred to as hepatics or liverworts. Like mosses and hornworts, they have a gametophyte-dominant life cycle, in which cells of the plant carry only a single set of genetic information.
Hornworts are a group of non-vascular Embryophytes constituting the division Anthocerotophyta. The common name refers to the elongated horn-like structure, which is the sporophyte. As in mosses and liverworts, hornworts have a gametophyte-dominant life cycle, in which cells of the plant carry only a single set of genetic information; the flattened, green plant body of a hornwort is the gametophyte stage of the plant.
Non-vascular plants are plants without a vascular system consisting of xylem and phloem. Instead, they may possess simpler tissues that have specialized functions for the internal transport of water.
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.
Sphagnum magellanicum, commonly called Magellanic bogmoss, Magellan's sphagnum, Magellan's peatmoss or midway peat moss, is a widespread species of moss found in wet boreal forest in the far south and southwest of South America, North America and Eurasia.
A moss bioreactor is a photobioreactor used for the cultivation and propagation of mosses. It is usually used in molecular farming for the production of recombinant protein using transgenic moss. In environmental science moss bioreactors are used to multiply peat mosses e.g. by the Mossclone consortium to monitor air pollution.
Splachnaceae is a family of mosses, containing around 70 species in 6 genera. Around half of those species are entomophilous, using insects to disperse their spores, a characteristic found in no other seedless land plants.
Sphagnum cuspidatum, the feathery bogmoss, toothed sphagnum, or toothed peat moss, is a peat moss found commonly in Great Britain, Norway, Sweden, the eastern coast of the United States, and in Colombia.
Pogonatum urnigerum is a species of moss in the family Polytrichaceae, commonly called urn haircap. The name comes from "urna" meaning "urn" and "gerere" meaning "to bear" which is believed to be a reference made towards the plant's wide-mouthed capsule. It can be found on gravelly banks or similar habitats and can be identified by the blue tinge to the overall green colour. The stem of this moss is wine red and it has rhizoids that keep the moss anchored to substrates. It is an acrocarpous moss that grows vertically with an archegonium borne at the top of each fertilized female gametophyte shoot which develops an erect sporophyte.
Polytrichum strictum, commonly known as bog haircap moss or strict haircap, is an evergreen and perennial species of moss native to Sphagnum bogs and other moist habitats in temperate climates. It has a circumboreal distribution, and is also found in South America and Antarctica.
Paludiculture is wet agriculture and forestry on peatlands. Paludiculture combines the reduction of greenhouse gas emissions from drained peatlands through rewetting with continued land use and biomass production under wet conditions. “Paludi” comes from the Latin “palus” meaning “swamp, morass” and "paludiculture" as a concept was developed at Greifswald University. Paludiculture is a sustainable alternative to drainage-based agriculture, intended to maintain carbon storage in peatlands. This differentiates paludiculture from agriculture like rice paddies, which involve draining, and therefore degrading wetlands.
Sphagnum papillosum, the papillose peatmoss, is a species of peat moss distributed throughout the northern hemisphere. Although sometimes confused with Sphagnum imbricatum and Sphagnum palustre, it is distinguished by its yellow-green to brown short, blunt branches and papillose chlorophyllose cells.
Buxbaumia viridis, also known as the green shield-moss, is a rare bryophyte found sporadically throughout the northern hemisphere. The gametophyte of this moss is not macroscopically visible; the large, distinct sporophyte of B. viridis is the only identifying structure of this moss. This moss can be found singularly or in small groups on decaying wood, mostly in humid, sub-alpine to alpine Picea abies, Abies alba, or mixed tree forests. This moss is rare and conservation efforts are being made in most countries B. viridis is found in.
Tortula muralis, commonly known as wall-screw moss, is a species of moss in the family Pottiaceae. T. muralis is found throughout the world.
Sphagnum australe is a species of Sphagnum found in southeastern Australia.