This is a much abused term, often misemployed to refer to any very wet piece of ground. In strict ecological use it refers to wet acid peaty deposits dominated by a particularly characteristic vegetation. The word bog derives from Scottish Gaelic boigeach but has passed into general English usage. In Northern Ireland the equivalent word moss, of northern English and Scots origin, is often used instead.
Bogs or mosses can be usually divided into those which have formed in depressions or in place of old lakes, with a fen as a transitional early stage, and those which form on high ground as a kind of blanket over the land surface (blanket bogs). Both kinds rely on a high rainfall for their continued existence.
Ireland was particularly rich in lowland bogs of a type known as raised bogs, which became more frequent further west owing to the moister climate. A large proportion of these lowland bogs have been cut away completely for fuel, and those that remain have also been cut to some extent.
Blanket bogs are also used as a source of fuel, known as turf. Turf (peat) is the compacted and only partially decomposed remains of plants, which when dried, can be burnt on on open fire. In the absence of large coal deposits, turf remains an important source of fuel in Ireland long after its use has declined elsewhere in western Europe.
Perhaps the most important plant of raised bogs is sphagnum moss, of which there are many different species. The vascular plants characteristic of raised bogs include:
The species characteristic of blanket bogs include:
These are a very common and characteristic type of habitat in Northern Ireland, frequently identifiable as wet ground lying substantially below the level of the adjacent roads and colonised by a wet woodland of birch and alder trees. There are extensive examples around Lough Neagh, sometimes erroneously referred to as the "Lough Neagh Fens". Characteristic species are: