Bog

A or  is a  that accumulates, a deposit of dead  material—often es, and in a majority of cases,  moss. It is one of the four main. Other names for bogs include mire, mosses, quagmire, and muskeg; alkaline mires are called fens. A baygall is another type of bog found in the forest of the Gulf Coast states in the United States. They are often covered in shrubs rooted in the sphagnum moss and peat. The gradual accumulation of decayed plant material in a bog functions as a.

Bogs occur where the water at the ground surface is and low in nutrients. In contrast to fens, they derive most of their water from precipitation rather than mineral-rich ground or surface water. Water flowing out of bogs has a characteristic brown colour, which comes from dissolved peat. In general, the low fertility and cool climate result in relatively slow plant growth, but decay is even slower due to low oxygen levels in saturated bog soils. Hence, peat accumulates. Large areas of the landscape can be covered many meters deep in peat.

Bogs have distinctive assemblages of animal, fungal and plant species, and are of high importance for, particularly in landscapes that are otherwise settled and farmed.

Distribution and extent
Bogs are widely distributed in cold,, mostly in  in the. The world’s largest wetland is the peat bogs of the Western Lowlands in, which cover more than a million square kilometres. Large peat bogs also occur in North America, particularly the and the Mackenzie River Basin. They are less common in the Southern Hemisphere, with the largest being the, comprising some 44000 km2 in southern South America. bogs were widespread in but have often been cleared and drained for agriculture. A paper led by in 2019 showed that peatlands across Europe have undergone rapid drying in recent centuries owing to human impacts including drainage, peat cutting and burning. A 2014 expedition leaving from Itanga village,, discovered a peat bog “as big as ” which stretches into neighboring.

Definition
Like all wetlands, it is difficult to rigidly define bogs for a number of reasons, including variations between bogs, the in-between nature of wetlands as an intermediate between terrestrial and aquatic ecosystems, and varying definitions between wetland classification systems. However, there are characteristics common to all bogs that provide a broad definition:


 * 1) Peat is present, usually thicker than 30 cm.
 * 2) The wetland receives most of its water and nutrients from precipitation  rather than surface or groundwater.
 * 3) The wetland is nutrient-poor.
 * 4) The wetland is strongly acidic (bogs near coastal areas may be less acidic due to ).

Because all bogs have peat, they are a type of peatland. As a peat-producing ecosystem, they are also classified as mires, along with fens. Bogs differ from fens in that fens receive water and nutrients from mineral-rich surface or groundwater, while bogs receive water and nutrients from precipitation. Because fens are supplied with mineral-rich water, they tend to be slightly acidic to slightly basic, while bogs are always acidic because precipitation is mineral-poor.

Ecology and protection


There are many highly specialized animals, fungi, and plants associated with bog habitat. Most are capable of tolerating the combination of low nutrient levels and waterlogging. is generally abundant, along with shrubs. The shrubs are often evergreen, which may assist in conservation of nutrients. In drier locations, evergreen trees can occur, in which case the bog blends into the surrounding expanses of boreal evergreen forest. are one of the more common herbaceous species. such as sundews (') and pitcher plants (for example ') have adapted to the low-nutrient conditions by using as a nutrient source. have adapted to these conditions through the use of mycorrhizal fungi to extract nutrients. Some shrubs such as  (bog myrtle) have in which  occurs, thereby providing another supplemental source of nitrogen. Bogs are recognized as a significant/specific habitat type by a number of governmental and conservation agencies. They can provide habitat for mammals, such as, , and beavers, as well as for species of nesting shorebirds, such as and. Bogs contain species of vulnerable reptilians such as the bog turtle. Bogs even have distinctive insects; English bogs give a home to a yellow fly called the hairy canary fly ('), and bogs in North America are habitat for a butterfly called the bog copper ('). In Ireland, the, the only known reptile in the country, dwells in bogland.

The in its  establishes bog habitats as a priority for conservation. Russia has a large reserve system in the. The highest protected status occurs in ( category IV);  and  are two prominent examples.

Types
Bog habitats may develop in various situations, depending on the climate and topography (see also ).

By location and water source
Bogs may be classified on their topography, proximity to water, method of recharge, and nutrient accumulation.

Valley bog
These develop in gently sloping valleys or hollows. A layer of peat fills the deepest part of the valley, and a stream may run through the surface of the bog. Valley bogs may develop in relatively dry and warm climates, but because they rely on ground or surface water, they only occur on acidic substrates.

Raised bog


These develop from a lake or flat area, over either non-acidic or acidic substrates. Over centuries there is a progression from open lake, to a marsh, to a fen (or on acidic substrates, valley bog), to a, as or peat accumulates within the lake. Eventually, peat builds up to a level where the land surface is too flat for ground or surface water to reach the center of the wetland. This part, therefore, becomes wholly rain-fed, and the resulting acidic conditions allow the development of bog (even if the substrate is non-acidic). The bog continues to form peat, and over time a shallow dome of bog peat develops into a raised bog. The dome is typically a few meters high in the center and is often surrounded by strips of fen or other wetland vegetation at the edges or along streamsides where groundwater can percolate into the wetland.

The various types of raised bog may be divided into:

Blanket bog
In cool climates with consistently high rainfall (on more than c. 235 days a year), the ground surface may remain waterlogged for much of the time, providing conditions for the development of bog. In these circumstances, bog develops as a layer “blanketing” much of the land, including hilltops and slopes. Although a blanket bog is more common on acidic substrates, under some conditions it may also develop on neutral or even ones, if abundant acidic rainwater predominates over the groundwater. A blanket bog can occur in drier or warmer climates, because under those conditions hilltops and sloping ground dry out too often for peat to form – in intermediate climates a blanket bog may be limited to areas which are shaded from direct sunshine. In climates a  form of blanket bog may occur, known as a. In Europe, these mostly very thin peat layers without significant surface structures are distributed over the hills and valleys of Ireland, Scotland, England and Norway. In North America, blanket bogs occur predominantly in Canada east of. These bogs are often still under the influence of water (groundwater). Blanket bogs do occur north of the 65th latitude in the northern hemisphere.

Quaking bog
A quaking bog, schwingmoor or swingmoor is a form of floating bog occurring in wetter parts of valley bogs and raised bogs and sometimes around the edges of acidic lakes. The bog vegetation, mostly anchored by sedges (such as ), forms a  approximately half a meter thick on the surface of water or above very wet peat. White spruce () may grow in this bog regime. Walking on the surface causes it to move – larger movements may cause visible ripples on the surface, or they may even make trees sway. The bog mat may eventually spread across the water surface to cover bays or even entire small lakes. Bogs at the edges of lakes may become detached and form.

Cataract bog
A is a rare ecological community formed where a permanent stream flows over a granite outcropping. The sheeting of water keeps the edges of the rock wet without eroding the soil, but in this precarious location, no tree or large shrub can maintain a roothold. The result is a narrow, permanently wet habitat.

Tourism uses
The Great Kemeri Bog Boardwalk is a tourist destination in, , , offering visitors a chance to explore the bog and its inhabitants. Short (1.4 km) and long (3.4 km) boardwalk trails are present, with an observation platform popular with photographers for sunrise and sunset scenes.

Industrial uses
After drying, peat is used as a, and it has been used that way for centuries. More than 20% of home heat in Ireland comes from peat, and it is also used for fuel in Finland, Scotland, Germany, and Russia. Russia is the leading exporter of peat for fuel, at more than 90 million metric tons per year. Ireland’s  (“peat board”) was one of the first companies to mechanically harvest peat, which is being phased out.

The other major use of dried peat is as a (sold as moss peat or sphagnum peat) to increase the soil’s capacity to retain moisture and enrich the soil. It is also used as a. Some ], notably in the whisky-producing region, use the smoke from  to dry the barley used in making.

Once the peat has been extracted it can be difficult to restore the, since peat accumulation is a slow process. More than 90% of the bogs in England have been damaged or destroyed. In 2011 plans for the elimination of peat in gardening products were announced by the UK government.

Other uses
The peat in bogs is an important place for the storage of carbon. If the peat decays, carbon dioxide would be released to the atmosphere, contributing to global warming. Undisturbed, bogs function as a. As one example, the peatlands of the former Soviet Union were calculated to be removing 52 Tg of carbon per year from the atmosphere. Therefore, the rewetting of drained peatlands may be one of the most cost-effective ways to mitigate climate change.

Peat bogs are also important in storing fresh water, particularly in the headwaters of large rivers. Even the enormous arises in the Ruoergai peatland near its headwaters in Tibet.

Blueberries, cranberries, cloudberries, huckleberries, and lingonberries are harvested from the wild in bogs. , wood that has been partially preserved by bogs, has been used in the manufacture of.

are also used for outdoor recreation, with activities including and hunting. For example, many popular canoe routes in northern Canada include areas of peatland. Some other activities, such as use, are especially damaging to bogs.

Archaeology
The anaerobic environment and presence of within bogs can result in the remarkable preservation of organic material. Finds of such material have been made in, , , , , and the. Some bogs have preserved such as ancient  logs useful in, and they have yielded extremely well preserved , with hair, organs, and skin intact, buried there thousands of years ago after apparent Germanic and. Excellent examples of such human specimens are and  in Denmark, and  found at  in England. At in  in Ireland, a 5,000-year-old  farming landscape has been found preserved under a, complete with field walls and hut sites. One ancient artifact found in various bogs is, large masses of fat, usually in wooden containers. These are thought to have been food stores, of both and.

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