Peatlands & Other Habitats
Bogs are peat-covered wetlands i.e. peatlands in which the vegetation shows the effects of a high water table and a general lack of nutrients. Peatlands make up 21% of county Offaly, 14% of north Tipperary and 12% of county Laois.
The bog surface is often raised relative to the surrounding landscape and isolated from mineralized soil waters. The surface waters of bogs are strongly acidic and the upper peat layers are generally nutrient poor. At least 40 cm of peat are present. The plant community is dominated by cushion forming Sphagnum mosses (peat mosses) and ericaceous shrubs. 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 only partially decomposes. Water infiltration through the bottom layer is extremely slow: a single raindrop can 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.
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.
Peatlands, or mires, can be divided into 2 distinct categories i.e. a Bog and a Fen.
Bogs & Fens
Fens are peatlands characterized by a high water table, but with very slow internal drainage by seepage. Similar to bogs, the surface water in fens is also generally nutrient poor and the peat layer is at least 40 cm thick. The vegetation in fens usually reflects the water quality and quantity available, resulting in three basic types: graminoid fens without trees or shrubs, shrub fens, and treed fens. Dominant plants include tamarack, sedges, grasses, reeds, cattails, and various mosses.
Fens began forming during the last Ice Age. As the ice retreated, large shallow basins were created and filled with water which was then colonised by fen vegetation. While fens can be isolated in the lowlands, bogs are always connected to other peatland units.
Bogs are mossy wetlands and can be divided into two distinct groups i.e Raised Bog (lowlands) or Blanket Bog (uplands). The word bog derives from the Irish for mire, bogach. Almost all of their water comes from rain and snow. Water in bogs is low in oxygen, very acidic and often cold! Sphagnum or peat moss is common in bogs. This moss has large cells with openings that absorb a lot of water. This makes bogs very spongy.
Bogs have low levels of oxygen in them because water doesn’t flow in and out of them easily. Low levels of oxygen and cold temperatures make it more difficult for fungi and bacteria to decompose dead plants quickly. This helps peat form.
Because decomposition happens so slowly, the soil and water in bogs is very acidic. Moss and some evergreen trees and shrubs thrive in bogs because they can tolerate the acidic soil conditions. Orchids, water lilies, pickerel weed, cranberries and blueberries also grow in bogs.
Insect-eating plants like pitcher plants and sundew often are found in bogs. They get a lot of the nutrients they need to survive from the insects they eat, so they can thrive in a bog’s nutrient-poor soil. Frogs, insects and insect-eating birds are also common in bogs. There aren’t many fish in bogs because of the low levels of oxygen in the water.
Bogs (Raised & Blanket)
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.
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.
- 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 - Wetlangriculture
Palus - Latin For Swamp
Paludiculture is wetland agriculture and forestry developed in Germany 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 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.
- 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.
Nature Based Solutions
Nature-based solutions refers to the sustainable management and use of natural features and processes to tackle socio-environmental challenges. These challenges include issues such as climate change, water security, water pollution, food security, human health, biodiversity loss, and disaster risk management