The stark landscape of the peat bog was once full of life – and a vital factor in the regulation and control of our carbon-dioxide emissions
IF THERE WAS a top 10 of degraded ecosystems on the planet, then industrial cutaway peatlands would certainly be a strong contender for the top spot. It is hard to believe, as the peat-extraction machines trundle across the peatland surface throughout the summer months, that these stark landscapes, seemingly devoid of life, were once ecological treasures, providing a home for rare plants and animals and, perhaps most importantly, acting as a vast store of carbon.
In recent years a huge volume of scientific studies has been published that shows natural or undamaged peatlands remove carbon from the atmosphere and store it for thousands of years. In doing so they help maintain and regulate the global climate.
But this remarkable function is destroyed when a peatland undergoes industrial extraction. In the first step, drainage ditches are installed, which lower the water table and release some of the carbon back to the atmosphere. Secondly, all the vegetation is removed from the surface, producing the flat, brown landscape that is a familiar sight in many of the midland counties.
The subsequent loss of carbon from these ecosystems is staggering. It is estimated that about 11 tonnes of carbon dioxide are released from each hectare of bare peat each year. If this figure were applied to all the industrial peatlands in Ireland it would mean that about 500,000 tonnes of carbon dioxide would be released to the atmosphere each year. This is in addition to the carbon given off each year by the combustion of peat at the three peat-burning power stations in the country. As the typical life span of a peatland production field can be up to 40 years, this amounts to a substantial amount of carbon.
At the recent UN climate conference talks in Cancún, in Mexico, negotiators agreed to look at ways of accounting for the carbon that might be saved through peatland-restoration projects and to incorporate them into any future climate agreements. Although other countries have embraced the idea of restoring these ecosystems once peat extraction has ceased, the focus in Ireland has instead been on developing alternative land uses, such as agriculture, forestry and amenity wetlands, or indeed to allow natural regeneration processes to take over the peatland.
The difficulty with restoration of industrial peatlands under Irish conditions is that it is almost impossible to re-create conditions that existed immediately before peat began to be extracted. In contrast to countries such as Canada, where the extracted peat is destined for use in horticulture and, as such, only the upper layers are extracted, Irish peat extraction results in the almost complete removal of the peat for energy generation.
The composition of the peat that remains will not support the type of vegetation characteristic of a mature bog. In particular, acid-loving plants, such as the sphagnum mosses, struggle to survive in extremely harsh environmental conditions that often include an erratically fluctuating water table, wind erosion and an absence of a nearby seed source. There is an obvious need for human intervention to help kick-start the restoration process.
Over the past number of decades Bord na Móna has been heavily criticised for the impact of industrial peat extraction on a natural ecosystem. In recent years, however, the company has promoted a greener agenda. This has included a commitment not to open up new peatlands in the decades ahead and to develop more sustainable forms of energy, such as wind power and biomass production.
As part of its present Integrated Pollution Prevention Control licence, Bord na Móna is also required to develop post-peat-extraction plans that mitigate or compensate for the more harmful effects of peat extraction. Given that large swathes of its current production areas are not deemed suitable for forestry or agriculture, the potential for peatland restoration or rehabilitation has come increasingly to the fore.
The centrepiece of restoration efforts has been the sprawling 6,500-hectare Oweninny peatlands, in northwest Co Mayo. From the 1950s until 2003 its peat was industrially extracted and burned in the power station at Bellacorick. The end of peat extraction resulted in a sharp reduction in the local workforce and left behind a deeply scarred landscape.
Fast-forward seven years and the changes have been dramatic. The drainage ditches that had been dug to help the extraction machinery were blocked, and the bare peat surface was landscaped. These measures resulted in a significant rise in the water table and a subsequent colonisation by plant species. Plants such as rushes were the first to become established; as time has passed they have in turn permitted the growth of clumps of moss around their bases, which have since spread voraciously across the rewetted peat surface.
Today only the barest hints of its industrial past are visible. These include rapidly dwindling areas of bare peat that peek out through the new plant communities, as well as heaps of fossilised timbers that had been removed during the bygone extraction days.
At first glance it would seem that at least some of the ecological processes have been restored at the peatland. Some of the characteristic plant species have returned, and the water table has been maintained at a suitably high level. But any suggestion that the restoration process has been a success is likely to be premature without an assessment of how restoration has affected the movement of carbon.
Dr David Wilson is an environmental consultant specialising in the measurement of greenhouse gases from soils. He is project co-ordinator of CarbonRestore; david.wilson@earthymatters.ie
That's gas: The effects of peatland restoration
The CarbonRestore project (ucd.ie/carbon restore) has investigated how restoration work seven years ago at the peatland has affected the movement of the greenhouse gases carbon dioxide and methane.
Funded initially by the Environmental Protection Agency and subsequently by Bord na Móna, the project has shown that the Oweninny peatland has been transformed from a very large source of carbon emissions to a significant carbon sink. A combination of a consistently high water table, low nutrient levels in the peat, and an almost evergreen plant composition means that more carbon is taken up by the peatland than is released back to the atmosphere.
Indeed, in terms of carbon gas movement, if a mature peatland is analogous to someone who is approaching retirement, then this “young” peatland resembles someone in his or her tearaway teenage years. The high rates of carbon uptake measured over the past two years reflect the dynamic changes that have occurred, and that are still occurring, at the peatland.
Where then will this all lead? If conditions can be maintained, the restoration process may be highly successful: the peatland will gradually accumulate more and more peat and may develop into something akin to its original state.
But if climatic conditions were to change, for example, and the area became progressively warmer in the decades ahead, the peatland may become more of a dryland ecosystem, dominated by birch and willow, which may release more carbon than their trees would take up.
Given that it took about 6,000 years for the original peatland at Oweninny reach maturity, we should probably allow this new version some time and space to find its way in the world.
