This glossary provides easy-to-understand definitions for the main scientific terms used on this website in relation to peatlands and their management.
A
- Acidic
Bogs have naturally acidic conditions because of the ion exchange processes carried out by sphagnum moss. They typically have a pH of 4.
- Acrotelm
The acrotelm is th top living layer of the bog that is above the level of permanent saturation.
- Anoxic
A lack of oxygen due to a high water table, which slows down decomposition and sequesters carbon within the peat.
B
- Biodiversity
A variety of animal, plant, bacteria, and fungi species that work together in an ecosystem. Bogs are an extremely important habitat in terms of their unique and plentiful biodiversity.
- Blanket bog
Blanket bog generally form in upland areas in the West of Ireland over 200m altitude. They are found where the average annual rainfall is greater than 1,200mm and where it rains at least 235 days each year. They get their name because the peat covers the land like a blanket.
- Bog
A peat covered or peat-filled area that is fed primarily by rainwater. The peat forms over thousands of years due to the lack of decomposition of plants and animals.
- Bord na Mona
The state company that was previously in charge of peat extraction and is now focusing on peatland horticulture and energy.
- Bryophytes
Non vascular plants such as mosses, lichens and liverworts. Mosses are integral to holding water on the bog and they are often known as ‘bog builders’.
- Bund
An embankment used to pond back water, to a greater extent than a dam.
C
- Callows
Shallower than fens (often with less than 40cm peat) but of somewhat similar origin and composition. Characterised by the fact that they were formed, and still occur today, in areas that were and sometimes still are regularly but seasonally flooded.
- Carbon Sequestration
The process of capturing and storing carbon dioxide. Dead plants accumulate to form peat as there is little decomposition in the water logged conditions. This carbon is taken in and stored within the peat.
- Catotelm
The deeper permanently water logged layers of the peat that may be several metres deep.
- Climax Ecosystem
The mature or stabilised stage in a successful series of communities.
- Cutover Bog
Any bog site cut by hand or mechanical means and where there is still an economic reserve of peat remaining. Up to 220,000ha of cutover bog is found in the midlands of Ireland, and a further 334,000ha in western Ireland.
D
- Dam
Structures built to block linear water courses.
- Designated Sites
Sites that have been given a special status under the EU Habitats Directive. The aim of a designated site is to conserve habitats, species, and heritage.
- Dipwell
Pipes in the surface of the bog that allow for the water table to be measured and monitored on the bog. They may also be called piezometers.
E
- Ecosystem Services
Vital services that the bog ecosystem provides for us to survive include flood prevention and carbon storage.
- Environmental Impact Assessment (EIA)
An EIA is a procedure which describes and assesses, in an appropriate manner, the direct and indirect effects of a project. A component of the EIA is the Environmental Impact Statement (EIS), which is a written report prepared by the developer of all relevant environmental aspects of the proposed development to be assessed.
- Eutrophication
Peatlands can become over-enriched from fertiliser inputs, negatively altering the ecology of the bog.
F
- Fen
These are groundwater fed peat wetlands forming over thousands of years. They tend to be more nutrient rich and less acidic than bogs.
H
- Hallow
Small depressions on the bog, permanently or temporarily filled with rainwater.
- Heath
A treeless, or nearly so, expanse of ground dominated by ericaceous plants. May or may not be peat covered.
- Hummock
Raised surfaces on the bog that sit above the water table (100cm x 100cm), usually formed from mosses.
- Hydraulic Conductivity
The rate at which water moves through a material.
- Lag
Swedish term for the outer margin of a raised bog, typically with a water course and/or fen (usually poor fen or fen woodland), into which water from the bog drains.
M
- Marl
A white deposit made from the congealed remains of animal shells, found at the base of shallow lakes where fen and raised bog later formed.
- Mesotrophic
Base status of waters intermediate between eutrophic and oligotrophic.
- Milled Peat
Peat in a crumb or powder form when air dried to approximately 50% moisture.
- Milling
A modern method of peat extraction in which the bare peat surface is milled to a depth of 10-50mm and harrowed to promote drying, prior to collection.
- Minerotrophic
Fed by groundwater.
- Mire
A general term applied to peat-producing ecosystems which develop in sites of abundant water supply. Some workers also include some mineral-based wetland within the compass of ‘mire’.
- Moss Peat
A horticultural peat product containing over 75% Sphagnum moss.
- Mud Turf
A traditional method of turf cutting. Peat is mixed with water and shaped into oblong pieces or sods with the hands.
N
- NHA
National Heritage Areas are the basic designation for wildlife and are considered important habitats with the aim of protecting the flora and fauna of the area.
- Nutrient Pollution
Septic tanks or fertilisers from nearby farms often add extra nutrients to bog and fen habitats. This can have long term negative effects for the health of the habitat.
O
- Oligotrophic
Nutrient poor (not necessarily base-poor).
- Ombrotrophic
Bogs, unlike fens, are fed mainly by rainwater.
- Overexploitation
Irish bogs have been historically exploited through large scale peat extraction/harvesting.
P
- Paludification
The development of wetland directly over mineral ground due to water logging through impeded drainage and/or increase in water supply.
- Peat
Organic soil material saturated with water for prolonged periods. For land to be classed as peatland, the depth of the organic soil material, excluding the thickness of the plant layer, must be at least 45cm on undrained land and 30cm on drained land.
- Peat Dams
These dams are cheap and made from highly humidified (decomposed) peat. These can be used to stop water draining from a bog, however they are not completely impermeable.
- Peat Hagg
A medium to large block of peat left behind after the surrounding turf has been cut out or eroded. The hang dries out and becomes dominated by heath or woodland vegetation.
- Peat Sods
Harvested peat from local bogs has fuelled homes in Ireland for many centuries. The fuel for the first sod peat fired power station was in Portarlington in 1950, however industrial scale harvesting has been carried out since 1825.
- Plastic Drain Piling
This technique can be used to block drains in the bogs. It is a good alternative to peat dams as it is impermeable.
- Poor Fen
Minetrophic mire, typically of pH less than circa 5.5.
- Priority Habitat
Habitats listed in Annex I of the EU Habitats Directive which are of the highest conservation status and require measures to ensure that they do not disappear.
R
- Raised bog
A domed peatland in the landscape fed by rainfall so that the peat is acidic. Raised bogs develop in lake basins. They can become quite large especially when the domes of peat from two adjacent lake basins coalesce.
- Ramsar Site
The Ramsar Convention of wetlands of International Importance obliges the State to recognise and conserve any internationally important wetlands especially for waterfowl. Sites are designated by the National Parks and Wildlife Service.
- Rewetting
A form of management used to retore drained peatlands, where the water table is raised by the blocking of drains. This can help reduce greenhouse gas emissions.
- Rich Fen
Minerotrophic mire, typically of pH more than circa 5.5.
S
- SAC
Special Areas of Conservation are strictly protected sites under the EU Habitats Directive that were chosen because of their conservation value. Listed habitats include blanket and raised bogs.
- Slean/ slane
A winged spade specially designed for cutting sods of turf.
- SPA
Special Protection Areas aim to protect sites of vulnerable bird species and all other regularly occurring migratory bird species within the European Community as a whole. The National Parks and Wildlife Service is responsible for designating SPAs.
- Sphagnum
A large genus of mosses found in wetlands throughout the world. Sphagnum mosses can hold up to 20 times their own weight in water. They are a major component of peat.
T
- Togher
A roadway across a bog, made from wood, gravel, or earth.
- Turbary Rights
The right of private individuals to cut turf for domestic purposes.
- Turf
Turf is peat that has been extracted from the ground. This is usually used for fuel.
- Turf Bank
A vertical cut face of a bog from which turf has been cut by hand or by machine.
W
- Water Table
Level at which the pore water pressure is equal to atmospheric pressure, forming the junction between saturated and unsaturated conditions.
- Wetland
Land that is saturated or partially covered with water.
X
- Xerophyte
Plants adapted to conditions of low water supply.
In 2024 the creation of this page was supported by the Peatlands and Natura Community Engagement Scheme operated by the National Parks and Wildlife Service.