A bog is a wetland type that accumulates acidic peat, a deposit of dead plant material. The term peat bog in common usage is not entirely redundant, although it would be proper to call these sphagnum bogs if the peat is composed mostly of acidophilic moss (peat moss or Sphagnum spp.). Lichens are a principal component of peat in the far north. Moisture is provided entirely by precipitation, and for this reason bog waters are acidic and termed ombrotrophic (or cloud-fed), which accounts for their low plant nutrient status. Excess rainfall outflows, with dissolved tannins from the plant matter giving a distinctive tan colour to bog waters.

Distribution and extent

Bogs are widely distributed in cold, temperate climates, 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. There are extensive bogs in Canada (called muskegs), Scotland,the Netherlands, Denmark, Estonia, Finland (26% boglands), and northern Germany. There are also bogs in the Falkland Islands. Ombrotrophic wetlands - i.e. bogs - are also found in the tropics, with notable areas documented in Kalimantan; these habitats are forested so would be better called swamps. Extensive bogs cover the northern areas of the U.S. states of Minnesota and Michigan, most notably on Isle Royale in Lake Superior.

Bog habitats

Bogs are challenging environments for plant life because they are low in nutrients and very acidic. Carnivorous plants have adapted to these conditions by using insects 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.

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, such as Tollund Man and Lindow man, buried there thousands of years ago after apparent Celtic human sacrifice.

Uses of bogs

Industrial uses

A bog is a very early stage in the formation of coal deposits. In fact, bogs can catch fire and often sustain long-lasting smouldering blazes, producing smoke and CO₂, thus causing 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 producer 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) 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.

These industrial uses of peat threaten the continued existence of bogs. More than 90 % of the bogs in England have been destroyed.

Other uses

Crops of blueberries, cranberries and lingonberries are grown in bogs.

Sphagnum bogs are also used for sport, but this can be damaging. Bog snorkelling is popular in England and Wales and has even produced the associated sport of mountain bike bog snorkelling. 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 60-meter trench cut through a peat bog.

The last Sunday in July is International Bog Day.

Bog is also a United Kingdom slang word for toilet.

Literature

Gothic Fiction is commonly set on the moor, an English bog. One example is "The Hound of the Baskervilles", a Sherlock Holmes story by Arthur Conan Doyle.

"The Bog People: Iron-Age Man Preserved", by P.V. Glob, is a classic study of archaeology. The book is about the iron-age culture of Denmark, and the victims of ritual sacrifice by strangulation. The corpses were thrown into peat bogs where they were discovered after 2000 years, perfectly preserved, down to their facial expressions, although well-tanned by the acidic environment of the Danish bogs.