Bog

, a bog in Henstedt-Ulzburg in northern Germany]] in northern Estonia]]

A bog, quagmire or mire is a wetland that accumulates acidic peat, a deposit of dead plant material—often mosses or, in Arctic climates, lichens.

Bogs occur where the water at the ground surface is acidic, either from acidic ground water, or where water is derived entirely from precipitation, when they are termed ombrotrophic (rain-fed). Water flowing out of bogs has a characteristic brown color, from dissolved peat tannins. Bogs are very sensitive habitats, of high importance for biodiversity.

Distribution and extent

Bogs are widely distributed in cold, temperate climes, mostly in the northern hemisphere (boreal). The world's largest wetlands are the bogs of the Western Siberian Lowlands in Russia, which cover more than 600,000 square kilometres. Sphagnum bogs were widespread in northern Europe: Ireland was more than 15% bog (Achill Island off Ireland is 87% bog), Scotland, Denmark, Estonia (20% bog lands), Finland (26%), northern Germany, Latvia (10%), the Netherlands, Norway and Sweden. There are extensive bogs in Canada and Alaska (called muskeg). There are also bogs in Patagonia and the Falkland Islands in the southern hemisphere. Ombrotrophic wetlands (of which bogs are an example) are also found in the tropics, with notable areas documented in Kalimantan; these habitats are forested so would be better called acidic swamps.

Types of bog

Range in the Upper Peninsula of Michigan, is an example of quaking bog formation.]]

Bog habitats may develop in various situations, depending on the climate and topography (see also hydrosere succession). In the 19th century it was thought that the bog itself somehow 'attracted' the rain that sustained it. The main types are:

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 marshy area, over either non-acidic or acidic substrates. Over centuries there is a progression from open lake, to marsh, then fen (or on acidic substrates, valley bog) and carr, as silt or peat fill 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 (ombrotrophic), 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: 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 ground water can percolate into the wetland.

Blanket bog

In cool climates with consistently high rainfall, the ground surface may remain waterlogged for much of the time, providing conditions for the development of bog vegetation. In these circumstances bog develops as a layer "blanketing" much of the land, including hilltops and slopes. Although blanket bog is more common on acidic substrates, under some conditions it may also develop on neutral or even alkaline ones, if abundant acidic rainwater predominates over the ground water. Blanket bog cannot 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 blanket bog may be limited to areas which are shaded from direct sunshine. In periglacial climates a patterned form of blanket bog may occur: string bog.

Quaking bog

Quaking bog or schwingmoor is a form of bog occurring in wetter parts of valley bogs and raised bogs, and sometimes around the edges of acidic lakes where bog is beginning to form. The bog vegetation forms a mat half a metre or so thick, floating over water or very wet peat. Walking on this surface causes it to move – larger movements may cause visible ripples of the surface, or they may even make trees sway.

Bog habitats

There are many highly specialised animals and plants associated with bog habitat. The species restricted to bogs are known as tyrphobionts and species characteristic of bogs but not confined to them are called tyrphophiles. Bogs are recognized as a significant/specific habitat type by a number of governmental and conservation agencies. For example, the United Kingdom in its Biodiversity Action Plan establishes bog habitats as a priority for conservation. Bogs are challenging environments for plant life because they are very acidic and low in nutrients. Characteristic plants are tolerant of acidic conditions: they include species of Vaccinium and royal fern (Osmunda regalis). Carnivorous plants such as sundews (Drosera) and butterworts (Pinguicula) have adapted to the low-nutrient conditions by using invertebrates as a nutrient source. The high acidity of bogs and the absorption of water by sphagnum moss reduce the amount of water available for plants. Some bog plants, such as Leatherleaf, have waxy leaves to help retain moisture. Bogs also offer a unique environment for animals. For instance, English bogs give a home to the boghopper beetle and a yellow fly called the hairy canary fly (Phaonia jaroschewskii). bog vegetation, Tříjezerní slať, Šumava.]]

Uses

Industrial uses

A bog is a very early stage in the formation of coal deposits. In fact, bogs can catch fire (see Burns Bog, for instance) and often sustain long-lasting smoldering blazes analogous to a coal seam fire, producing smoke and carbon dioxide which can cause health and environmental problems. After drying, peat is used as a fuel. 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 Bord na Móna ("peat board") was one of the first companies to mechanically harvest peat.

The other major use of dried peat is as a soil amendment (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 mulch. Some distilleries, notably Laphroaig, use peat fires to smoke the barley used in making Scotch whisky. More than 90% of the bogs in England have been damaged or destroyed.

Other uses

at Polly's Cove, Nova Scotia]] Blueberries, cranberries, cloudberries, huckleberries and lingonberries are harvested from the wild in bogs. Bog oak, wood that has been partially preserved by bogs, has been used in manufacture of furniture.

Sphagnum bogs are also used for sport, but this can be damaging. All-terrain vehicles are especially damaging to bogs. Bog snorkeling is popular in England and Wales. Llanwrtyd Wells, the smallest town in Wales, hosts the World Bog Snorkelling Championships. In this event, competitors with mask, snorkel, and scuba fins swim along a trench cut through a peat bog.

Archaeology

and boulders at the Stumpy Knowe near South Auchenmade, Ayrshire, Scotland.]] The anaerobic environment and presence of tannic acids within bogs can result in the remarkable preservation of organic material. Finds of such material have been made in Denmark, Germany, Ireland and the United Kingdom. Some bogs have preserved ancient oak logs useful in dendrochronology, and they have yielded extremely well preserved bog bodies, with organs, skin, and hair intact, buried there thousands of years ago after apparent Germanic and Celtic human sacrifice. Excellent examples of such human specimens are Haraldskær Woman and Tollund Man in Denmark, and Lindow man found at Lindow Common in England. At Céide Fields in County Mayo in Ireland, a 5,000 year old neolithic farming landscape has been found preserved under a blanket bog, complete with field walls and hut sites. One ancient artifact found in bogs in many places is bog butter, large masses of fat, usually in wooden containers. These are thought to have been food stores, of both butter and tallow.

See also

{| |-valign=top |

List of bogs

List of raised and transitional bogs of Switzerland

String bog

Blanket bog

Bog body

Bog butter

Bog iron

Bog-wood

Blackwater river

Differences between bogs and other wetlands

|

Irish Peatland Conservation Council

Marsh

Muskeg

Poor fen

Sods

Sphagnum

Swamp

Wetland

Will-o'-the-wisp

Kerry bog slides

|}

References

Bibliography

Aiton, William (1811). General View of The Agriculture of the County of Ayr; observations on the means of its improvement; drawn up for the consideration of the Board of Agriculture, and Internal Improvements, with Beautiful Engravings. Glasgow.

External links

Ballynahone Bog

Black Spruce Bog Describes a forested bog type of North America

Bog bodies

Germany's Endangered Bogs - slideshow by Der Spiegel

Preserve peat bogs' for climate BBC 28.3.2007

Category:Landforms Category:Types of soil Category:Pedology Category:Wetlands