Peatland decline in Ireland

Bogland close to Allenwood
Courtesy of Dr. Arnold Horner.

Ireland’s natural peatlands used to cover an estimated 17% of the landscape of the Republic of Ireland, an area of over 1 million hectares, where over 300,000 hectares were classified as raised bog and over 700,000 classified as blanket bog. Currently natural peatlands cover just 269,270 hectares of Irish land, with land affected by domestic turf-cutting covering 612,380 hectares, afforested peatland covering 301,700 hectares, farmed peatland 295,000 hectares, industrial peatland 70,000 hectares, and rehabilitated cutaway peatland 18,000 hectares. Of the 70,000 hectares of industrial peatland, 57,000 belongs to Bord na Mona and the rest is cut by private companies extracting peat for horticultural purposes (information from The Soils of Ireland, Peatlands Chapter).

Raised bogs are typically located in the midlands of Ireland, while blanket bogs tend to occur in the west of Ireland where annual rainfall exceeds 1250mm and it rains on over 250 days of the year. Since the 1940s the quantity and quality of Irish peatlands has declined, mainly due to mechanized turf extraction, afforestation in the 1950s, agricultural intensification following Ireland joining the European Union in 1973, and land reclamation from drainage of the bogs.

Drainage of bogs in the midlands lowered the water table of the bogs which exposes the upper layers of the peat to the air, destroying the upper layer of the bog where sphagnum mosses grow and accumulate over time to increase the depth of the bog itself, the vegetation then changes from mosses to species which thrive in drier conditions like heather.

Similarly, intensive grazing of bogs by sheep removes the natural vegetation and exposes the bog to erosion via wind, rain and freeze-thaw action, compromising the integrity of the bog itself. This erosion has consequences in other areas, as water quality in the rivers and streams which drain the bogs can be compromised by the increased levels of silt in the water which makes life more difficult for the creatures living in these water-bodies.

Over 40% of the afforestation (planting trees) on Irish soils has occurred on peatland soils, this has the effect of reducing the integrity of the peat soils as tree roots permeate the soil leading to subsidence of the soil and exposing the peat to the elements, leading to oxidation (the release of CO₂) (EPA, 2002). Over 218,000 hectares of blanked bog and 6,175 hectares of raised bog have been afforested to date, with 80% of this managed by Coillte, the Irish forestry company ran by the state (IPCC).

Burning of peatlands is also a common occurrence in Ireland, typically to remove the vegetation in order to accommodate the cutting of turf. Controlled burning of bogs is also carried out to promote the growth of new heather for sheep grazing, but this process can have severe negative consequences if not undertaken properly. This burning releases large amounts of carbon that had been stored in the peat for thousands of years, and contributes to increasing amounts of greenhouse gases in the atmosphere, contributing to climate change (IPCC).