FACTS ABOUT IRISH PEATLANDS
What is ‘peat’ and what are ‘peatlands’?
Peatlands are wetland ecosystems that are characterised by the accumulation of organic matter called ‘peat’ which derives from dead and slowly decaying plant material under high water saturation conditions.
Definitions agreed within the Bogland project:
Peat: accumulated, partially decomposed plant material (mainly dead Sphagnum, sedges and grass).
Peat soil: organic soil materials which have sedentarily accumulated and have at least 30% (dry mass) organic matter over a depth of at least 45 cm on undrained land and 30 cm deep on drained land; the depth requirement does not apply in the event that the peat layer is over bedrock.
Peatland: a geographical area where peat soil occurs. For mapping purposes, a peatland should cover a minimum spatial extent of 1 ha.
Why are peatlands so important to us?
cover a considerable area in
Much of Irish
peatland has been extensively modified by man. Of course peat has been used in
The problems of peatland utilisation and degradation have far reaching implications on our environment and socio-economic well-beings. This is because peatlands are one of the most important natural ecosystems in the world which have key values for biodiversity conservation, climate regulation and support of human welfare. Peatlands are beautiful cultural landscapes with a unique biodiversity and they also provide mankind with many services.
Peatlands contain a fascinating biodiversity, many specialised organisms live only on bogs as they have adapted to the unique conditions. Vegetation is very specialised in this acidic and wet environment. Bogs are a refuge for several rare plants and animals. But biodiversity is not limited to the visible plants and animals, there is a huge diversity in the soil and aquatic living things. We have just begun to understand the vastness of microbial species living in the peat and their role in carbon fluxes and eventually global climate.
Peatlands have also a great value for archaeologists who have learnt a lot about our ancestors from the bog bodies. Interestingly, it is in the bog that we can find what kind of climate our ancestors lived in.
Peatlands are the single largest terrestrial store of carbon (storing more carbon than the vegetation of the whole world (they contain nearly 30% of all carbon on the land).
How are peatlands formed?
Bog formation started at the end of the last glaciation, some 10,000
years ago and continues to the present day in what we call near-pristine bogs.
Initially, peat formation was confined to shallow lakes and wet hollows. As
plants growing at the margins of open water and floating in the water died,
their remains accumulated as lake peat also known as reed peat. The dead plant
remains began to accumulate as fen peat as under water decomposition of the
organic matter is extremely slow. In time, the fen peat layer accumulated to
such a depth that the roots of the plants growing on the peat surface were no
longer in contact with mineral-rich ground water. When this happened, the only
source of minerals for the plants came from rainwater. As a result new plant
species appeared on the peat surface, these were able to grow in a mineral-poor
environment. Amongst them, bog mosses known as Sphagnum species.
What are the different types of peatlands in
When did our peatlands become severely depleted?
The original cover of peatlands was 17% or 1,177,670ha. More recent mapping methods have been used to develop a Derived Irish Peatland Map which would indicate that the current land cover is just under 15%. Bogs have suffered from a plethora of disturbances and it is argued that as little as 85,00ha (11%) of blanket bogs and 25,189ha (8%) of raised bogs remains relatively intact.
Peat has been
a source of fuel in
traditional hand-cutting, Irish peatlands remained largely untouched up to
modern times. In the nineteenth century peat was the main fuel available to a
population that had expanded to more than 8.2 million. The disappearance of
peatlands in the eastern part of
The introduction of large-scale mechanised peat extraction in the 1940s and the establishment of the Irish peat board (Bord na Móna) as a semi-state body in 1946 were direct results of government policies introduced to deal with the increasing difficulties associated with importing fuel supplies. By developing Irish peatlands for electricity generation, the government not only redressed the trade imbalance, but also stimulated rural economies where the peatlands were located. The introduction of a grant aid scheme under the Turf Development Act (1981) also enabled many small-scale extraction programmes to take place, either for energy production or for horticultural purposes.
Bord na Móna
owns 80,000ha of peatland and harvest 4 million tonnes of milled peat per year.
The main market for milled peat is the energy sector both for burning in power
stations and for domestic consumption via briquettes production. Peat represents
5% of primary energy requirement in
to Bord na Móna, private peat producers also harvest peat and in total it is
estimated that 100,000ha is being utilised for peat harvesting in
Industrial peat extraction results in complete loss of the peatland ecosystem, and is the ultimatum form of degradation. The scope to restore any peatland from these cutaway is limited but Bord na Móna has succeeded to restore peat-forming vegetation on a large-scale cutaway bog in Bellacorick in Co. Mayo. Along with other after-uses such as forestry and windfarms, cutaway peatlands can be rehabilitated and benefit the environment.
Other threats have produced even more degraded peatlands:
-Turf-cutting: Since the 15th century, traditional turbary (or the right of private individuals to cut turf for domestic use) has been responsible for the loss of 544,000ha of raised and blanket bogs, or 46% of the original peatland area. While turf-cutting is generally concentrated at bog edges, the drainage and the edge effects can be manifested as subsidence within the relatively intact parts of the bog as evidence in Clara bog, the bog is sinking when it should be growing up! The project has identified this threat as very serious if the bog is to survive in the future. There is a Government funded scheme which aimed at phasing out all turf-cutting at the edges of protected sites such as Clara by 2008. It is critical that the Government keep this promise.
-Afforestation: In 2007, the Forest Service completed the first National Forest Inventory which showed that 43% or 301,770ha of the total forest estate is located on peat soils, of which 218,850ha is on blanket peat. Coillte owns 175,136 ha of blanket peat.. Coillte have to be commanded for their new work on restoring just under 2000ha of blanket bogs (for example in Glenlahan in the Slieve Bloom) and a further 570ha of raised bogs thanks to the support of funding from the EU LIFE-Nature Programme. Within the project, we have worked with Coillte to look at the effect of restoring blanket bogs in terms of greenhouse gas emissions.
Extensive areas of
blanket bog have been severely degraded due to increased numbers of grazing
sheep, particularly in the west of
loss in plant cover leads to exposure of bare peat surfaces and subsequent
erosion of peat to the underlying mineral soil in some places. This in turn led
to acidification of lakes and siltation of the spawning beds of salmonids in
these regions. In the period 1987-1997 it is estimated that overgrazing damage
had left 7% of
in E.U. policy and payment schemes have resulted in a significant reduction of
sheep numbers on the blanket bogs and vegetation will recover. Within the
project, we are working with Teagasc and NPWS to devise appropriate grazing
What is the future of Irish peatlands?
When peat is used for electricity generation, for heat and for horticultural purpose, one must bear in mind that it takes thousands of years to form and what we are left with is rarely conducive to peat forming vegetation.
Complete restoration is often difficult as a result of the complexity of the peatlands, the conditions under which they form and the long-term scale of peat growth.
This is becoming more and more appreciated by the public and new surveys are under way within the project to understand how the public appreciate these values and how much they are prepared to pay to keep them. We need to evaluate the impact of using our peatlands in terms of monetary and non-monetary indicators.
The authors are grateful for the support of the Environmental RTDI Programme 2000-2006, financed by the Irish Government under the National Development Plan and administered on behalf of the Department of the Environment, Heritage and Local Government by the Environmental Protection Agency.
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Last updated: 10 December 2007
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