Peatlands
Peatlands make up 21% of Offaly. Although they can be divided into either bogs and fens, they’re composed of diverse integrated systems of ecological niches, creating a micro-topographical menagerie of habitat for Ireland’s most beautiful and peculiar life.
Wetlands are areas inundated with water long enough for the vegetation community to adapt to nutrient-poor conditions. Peatland is a type of wetland, distinct as conditions naturally create a peat layer at the surface. This peat is created by a carpet of Sphagnum mosses that thrive in nutrient-poor and waterlogged conditions.
To protect themselves from bacteria Sphagnum leaves release a pectin-like substance called sphagnan which inhibits microbial activity. Essentially, this prevents the breakdown of organic matter. Sphagnum grows from the top and dies at the base but it doesn’t decompose.
Accordingly, active peatlands have two layers: A thin layer of peat-forming Sphagnum on top (between 10-40cm) and a relatively inert, permanently waterlogged and compacted peat store beneath: this is called the catotelm, or turf.
Water infiltration through the bottom layer is extremely slow: a single raindrop takes 90 years to filter downwards through the 10m thickness of a raised bog system. Accordingly, draining these peatlands is catastrophic. Sphagnum dries and dies, and the organic matter is exposed and begins to decompose.
Types Of Peatlands
Peatlands, or mires, can be divided into two distinct categories: Fen and Bog.
A Fen is nutrient-rich, usually with reeds or cattails, and fed by Groundwater.
A Bog gets sustenance from the atmosphere: bogs can be divided into Raised Bog (lowlands) or Blanket Bog (uplands). The word bog derives from the Irish for mire, bogach.
Fens
Fens are dependent on the water within the catchment or groundwater for their nutrition. As they receive their waters from the land, they’re influenced by happenings in the catchment. Bogs feed into the catchment from headwaters and receive their substance from the atmosphere. While fens can be isolated in the lowlands, bogs are always connected to other peatland units.
Fens began forming raised bogs during the last Ice Age. As the ice retreated, large shallow basins in our midlands were created and filled with water which was then colonised by fen vegetation. Growing from the bed of the basin, this vegetation began to accumulate atop itself over thousands of years and has since risen up to 10 meters in height
Bogs: Raised & Blanket
Bogs, alternatively, are supported by precipitation. The sensitive sphagnum moss heads are capable of binding with suspended nutrients as they pass by in the mist and fog, fall as rain or settle as dew. Intact bogs, unlike fens, attenuate pluvial flow. They are ‘shedding systems’ which gradually releases water into the catchment.
Blanket bogs are generally much shallower than raised bogs (<6m) and form on highly podzolized glacial tills, created by ancient broadleaf forests. Deforestation on Ireland’s hills during the Holocene, coupled with a change in climate, created the conditions for the development of these bogs- ‘paludification’.
The sphagnum moss is hydrophobic and can hold water in a blanket bog up to an angle of 35 degrees. These are highly diverse landscapes with micro-topographic ecological niches which are often composed of a mixture of both bog and fen units.
Raised Bog
Common in the Irish lowlands. Between 3-12 meters of deep acidic peat that originated from a shallow lake basin. Thousands of years of vegetation growth atop its self creates a domed effect. The raised bog is usually surrounded by ground-fed Fen peatland and the edges have often been cut away for turf. Not a single Raised Bog remains completely intact in Ireland.
Small scale mosaics of plant communities reflect the complex micro-topography of hummocks and hallows on the bog’s surface.
Plant communities differ if the ground is dry or wet. Downy Birch and Scots Pine will begin encroaching from the edges if the bog is drained. Their root networks hasten the decomposition of the peat and release more emissions.
Blanket Bog
Upland blanket bogs occur over 150m and is widespread on the hills and mountains of Ireland. They absord nutrients from the atmosphere so grow much slower than Raised Bog: they’re normally 1-2 meters deep.
Vegetation is usually dominated by deergrass, cottongrasses and ling heather. If the area is undamaged, then there is usually a carpet of Sphagnum mosses. These sensitive plants are the bog builders, growing atop themselves and compacting growth beneath, which turns into peat.
Lowland blanket bogs is usually confined to the western seaboard with very high rainfall. They’re distinguishable by the scattered pools and channels, the small peat-basin lakes and streams with gullies and swallow holes which lead to underground drainage systems.
Other Habitats
- Grassland: There are very view, if any, natural grasslands left in Ireland. Most have been modified by generations of harrowing, grazing, seeding and fertiliser application. Intensively managed, or highly modified grasslands, involve regular re-seeding to produce a homogeneous crop of rye-grasses. It is becoming more popular to seed with multi-seed crop which allows for similar yields to industry-standard rye-grass monocultures but with a lot less inorganic nitrogen fertilisers. Saving up to of €120/acre per year depending on the reduction in nitrogen used.
- Scrub: Without interference, these grasslands would turn to shrub with stunted trees or brambles. This developing habitat is very valuable to bird and insect life.
- Native Woodland: Consisting of native trees that rise about the 5 meter threshold of scrub
Paludiculture Wetland Agriculture
Palus - Latin For Swamp
Paludiculture is wetland agriculture and forestry that enhances the ecosystem service potential of peatland. By restoring the water table we facilitate the planting and harvesting of wetland crops. The cultivation of Cattail, for example, can be used to create load-bearing thermal insulation (Typha Board).
Cattail grows naturally in fens and lowland bog. The crop is sown and harvested after the second year and produces between 15-20 tonnes per hectare. The Cattail is collected, shredded and moulded with a mineral bond into a high-quality insulation board with good workability and fire resistance (Class F120 with 120mm).
The production of this indigenous construction material can diversify farm income and reduce our reliance on imports within the construction sector. Typha Board requires low energy input and can be sustainable throughout the supply chain.
Not only will working with the wetland nature of peatland subsequently improve water quality and biodiversity, by accounting for the GHG emissions sequestered the farmer receives secondary production in the form of Carbon Credits.
Paludiculture was developed in Germany and hasn’t yet been adopted in Ireland. We’re presented with an opportunity: we have vast expanses of suitable peatlands, the crop is valuable, and the development of the production line will generate new employment.
We’re establishing pilot farms in the midlands, in conjunction with stakeholder engagement and market development, to trial paludiculture in Ireland.
Paludiculture Crops
- Reed canary grass- Energy (combustion, biogas).
- Common reed- Construction materials and energy.
- Sedges- Energy (combustion, biogas), fodder and litter.
- Cattail- Construction materials, fodder, energy (biogas).
- Black Alder- Construction materials, furniture, energy.
- Peat mosses (Sphagnum)- growing media.
