The Peatlands of Ireland
Taken from Bord na Móna, Fact Sheet, no. 1.
FACT SHEET 1.0
Peatlands are a very important part of the history, culture and economy of Ireland. These vast areas of land are amongst our great natural assets and their uniqueness can be compared to the semi-tropical and tropical rainforests in a number of remote regions in the World.
PEATLANDS cover 16.2% of the land mass of the island of Ireland and 17.2% of the area of the Republic. This percentage is only exceeded in global terms by three countries, namely, Finland, Canada and Indonesia. See Figs. I & 2.
DEFINITION OF PEATLANDS:
Peatlands (or Boglands) are areas where peat accumulates over hundreds, or thousands, of years and where depths are at least 45 cm. However in the vast majority of instances, their depths range between 2m and 12m.
WHAT IS PEAT:
Undrained peat consists of 95% water and 5% solids material. The solids are composed of the partly decayed remains of a variety of plants. The plant remains include: roots, stems, leaves, flowers and seeds. In some locations the solids material is made up of a mixture of partly decayed remains of plants and trees. In such cases the residues of trunks and roots of trees such as yew, oak, pine and birch are found.
TYPES OF PEATLAND Three types occur in Ireland. (See Fig. 3)
Fens are bogs which form from vegetation which is fed from ground waters rich in nutrients. They are very often an early stage in the formation of raised bogs which grow on top of the fen. Their depth can vary depending on their location but an average depth of approx. 2.2 metres is common.
These are found normally in the midlands where moderate levels of rainfall occur annually. They have a dome-shaped surface and are very deep in some areas where depths of over 13 metres have been recorded. Their average depth is 7.5 metres.
These are found chiefly in the West of Ireland and also in mountain areas throughout the country where rainfall levels are relatively high annually. They are shallow bogs which form a blanket-like layer over the surface of the underlying mineral soil. Their average depth is 2.6 metres.
AGE OF PEATLANDS:
The oldest peats within the vast areas of Ireland's peatlands were formed in the midlands about 9000 years ago, and younger peats derived from different vegetation sources have formed since that time. (See Fig. 4)
PLANTS AND PEATLANDS:
The vegetation that grows on peatlands, in their natural state, is specially adapted to a habitat which has a low nutrient soil and is waterlogged for most of the year. There is an interesting variety of plant species to be found on the different peatland types. These include:
Common Reed, Saw Sedge, Black Bog Rush, Purple Moor Grass, Fen Rush,Pondweed, Fen Orchid
Sphagnum Mosses, Bog Cotton, Ling Heather, Bog Rosemary, Bog Asphodel, Sundew
Black Bog Rush, Bog Cotton, Purple Moor Grass, Deer Sedge, Tormentil, Butterwort
Interesting plants include: the Sundew and Butterwort which supplement their soil food intake by capturing and digesting insects, these are known as insectivorous plants; Bog Cotton is easily recognisable as it produces an impressive array of woolly white heads in the late spring and summer months; Heathers produce an attractive purple coloration in the late summer and autumn and the Sphagnum Mosses are very special plants as they possess the rare property of holding up to 20 times their own weight of water in their pores and cells.
WILDLIFE IN PEATLANDS:
Peatlands in their natural undrained state are inhospitable places for many wildlife species. This is due to a number of factors which include:-the restricted nature of food bearing vegetation on the low nutrient peatland soils; the mainly waterlogged surface of this terrain and the scarcity of significant areas of trees which would provide shelter for many species of wildlife. Some birds use peatlands as safe roosting and nesting sites. The most common wildlife found on different peatlands include:
Snipe; Skylark; Kestrel; Red Grouse; Curlew; Meadow Pipit; Golden Plover.
Cranefly; Dragonfly; Damselfly; Emperor Moth; Large Heath Butterfly; Water Scorpion; Great Diving Beetle; Black Slug.
Fox; Hare; Otter; Deer; Common Frog.
Peat is an excellent material for preserving objects which have been buried over long periods of time, sometimes for thousands of years. This is due to the acidity of the peat and to the deficiency of oxygen within the peatland environment which prevents the normal process of decay from taking place.
Many interesting sites have been preserved underneath certain peatlands and many fascinating objects have been found buried within the peatland layers.
EXAMPLES OF SITES OF FORMER HABITATIONS PRESERVED UNDERNEATH PEATLANDS INCLUDE:
Prehistoric farms such as the Ceide Fields (Stone Age) in North Mayo and Lough Boora Campsite (Stone Age) and Clonfinlough Settlement (Bronze Age) in Co. Offaly.
Objects hidden or lost in peatlands include:
Bog Butter; Quernstones; Gold Bracelets; Stone Axe-heads; Trackways or Toghers;
GENERAL CHARACTERISTICS OF PEATLANDS
Peatlands are acidic soils which in their undrained state have a high water content. They also have an extremely high organic content and low ash (i.e. inorganic) content.
Typical values are given in the table I below:
Peatlands can be used for a variety of purposes. These include:
PRINCIPAL USES OF PEAT:
Peat and peat products can be used industrially for a variety of purposes; these are shown on Fig. 5.
PEATLANDS IN THEIR NATURAL STATE:
These are unique environments; therefore it is very important that excellent examples of the various peatlands are conserved for posterity.
Peatlands can be used for research purposes where students can study a variety of subjects, for example, plants, wildlife, ecology, vegetation history (from macrofossils and pollen), hydrology, decomposition etc.
PARAMETER TYPICAL VALUES Peat Soil pH 3.8 to 6.5 Water Content (undrained) Approx. 95% Solids Content (undrained) Approx. 5% Organic Content (anhydrous) Approx. 96% Ash (or inorganic) content (anhydrous) Approx. 4%