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Cutaway & Cutover Bog Habitats

During the summer of 1999 IPCC undertook a habitat survey of cutaway raised bogs in the midlands of Ireland. The aims of the survey, which was funded by the Heritage Council, Bord na Móna and the Patagonia Fund, were to identify and characterise the principal vegetation types occurring on cutaway raised bogs; and to undertake a baseline survey of the invertebrates and other fauna occurring in each habitat identified.

During the 1999 field survey we visited 14 cutaway bog sites which were either cut mechanically or traditionally by hand. In house we also had relevant species information relating to a further 13 cutaway bog sites surveyed by IPCC from 1991 to 1999.

An extensive body of information has been built up on cutaway bogs from our research work including: 75 plant species lists, 31 quantitative vegetation descriptions and 57 faunal species lists. The figures for the biodiversity present in cutaway bogs are impressive. We recorded 118 plant, moss, fungus and lichen species and 110 mammals, reptiles, amphibians, birds, fish and invertebrates. From the plant species data obtained IPCC have identified 12 different vegetation communities occurring in cutaway bogs in Ireland.

Common Club Rush uses underground stems to quickly invade cutaway bogs. It forms mono-dominant stands in these areas. Photo: Peter Foss

The vegetation types identified range from pioneer communities, established on bare peat, to mature wetland and woodland communities found on cutaway bogs that have been abandoned for 50 years or more.

The vegetation types identified on cutaway bogs

1. Drain Communities
2. Sphagnum bog holes
3. Calluna (heather) heathland
4. Grassland
5. Eriophorum angustifolium (bog cotton) peat drying fields
6. Scirpus caespitosus (deer sedge)-Erica tetralix (cross-leaved heath) Heath
7. Pine-Heath Woodland
8. Willow-Birch Woodland
9. Wetland and Reed Bed
10. Regenerating Raised Bog
11. Pioneer Plant Communities
12. Secondary Fen

Birch and Willow Woodlands
Mature birch and willow woodlands contained an important diversity of species. Structurally the woodlands had a maximum of three layers of vegetation: the canopy layer, the dwarf shrub layer and the ground layer. At one site in the Bog of Allen in Co. Kildare a diverse epiphytic lichen flora had developed on the branches of the trees to include 8 different species with crusty, leafy and bushy growth forms. In this woodland a specialist insect - the Red-necked Footman (Atolmis rubricollis) was recorded. Its larva eats epiphytic lichens, and is a wonderful example of inter-dependence between plant and animal.

Regenerating Raised Bog Vegetation
Regenerating raised bog vegetation is another important habitat of cutaway bogs and is listed in the EU Habitats Directive. Across Europe raised bogs are one of the most endangered habitats because they have been over-exploited to the point of exhaustion in many of the countries in which they formerly occurred. Many of the regenerating raised bog sites examined during the cutaway bog survey had a diversity of Sphagnum mosses, the main peat forming plant on raised bogs. With careful manipulation of the water table these sites could be maintained in their present form. At one site, in the Bord na Móna Blackwater Works, management work is being undertaken to raise the bog water table, so as to maintain the characteristic flora and allow for the regeneration of peat forming Sphagnum mosses.

Secondary Fens
In formerly abandoned cutaway bog areas where peat was removed to the fen peat level, species-rich fen vegetation regenerates once cutting stops. This is also a threatened vegetation type in Europe. The moss flora is indicative of the mineral enriched conditions prevailing and includes Scorpidium scorpioides, Ctenidium molluscum, Campylium stellatum, Cinclidotus fontinaloides, Calliergon cuspidatum and Fissidens adianthoides. Some interesting flowering plants occurred in these habitats including the carnivorous bladderwort (Utricularia intermedia) and butterwort (Pinguicula vulgaris), lesser water-plantain (Baldellia ranunculoides), black bog rush (Schoenus nigricans) saw sedge (Cladium mariscus) and several species of Carex sedge.

Plant Colonisation Strategies
A number of plants successfully colonised the cut, bare peat surface using a system of underground stems or rhizomes. Plants employing this strategy included, reed (Phragmites australis), arrowgrass (Triglochin palustris), bulrush (Typha latifolia), horse tail (Equisetum arvense), common club-rush (Schoenoplectus lacustris), bog cotton (Eriophorum angustifolium) and rush (Juncus effusus).

Other plants which are able to rapidly invade the bare peat, are species able to produce new plants at nodes on overground stolons such as bramble (Rubus fruticosus), creeping bent grass (Agrostis stolonifera), creeping buttercup (Ranunculus repens) and field bindweed (Convolvulus arvensis).

Birds
During the IPCC survey of cutaway bogs the skylark was the most commonly encountered bird species, associated with open habitats, particularly the regenerating raised bog vegetation, but it also occurred in pioneer vegetation habitats on industrially cut bogs. Two other open ground species encountered were meadow pipit and snipe.

The sedge warbler, a reed bed specialist was recorded on one of the created wetlands within the Bord na Móna works at Blackwater, where a small lake surrounded by reed beds and other wetland plants occurred.

In the birch and willow woodlands, magpie, wood pigeon, siskin and wren were recorded.

Butterflies
Cutaway bog habitats support several species of butterfly and moth including the specialist - the Large Heath Butterfly (Coenonympha tullia). On regenerating raised bog vegetation the larva finds an abundance of its food plant - bog cotton - while adults take nectar from cross-leaved heath. We recorded three adults on one site and actually witnessed them sucking nectar from cross-leaved heath. This species has suffered a decline throughout its European range due to loss of habitat.

We recorded the Marsh Fritillary (Eurodryas aurinia) at two sites, in habitats where there was an abundance of the Devil's Bit Scabious (Succisa pratensis), the food plant of the larva. The Marsh Fritillary is one of the most rapidly declining butterflies in Europe, due to widespread loss of habitat.

Other species recorded were: Broom Moth, Cinnabar Moth, Drinker Moth, Emperor Moth, Fox Moth, Green-veined White, Large White, Latticed Heath Moth, Meadow Brown, Oak Eggar, Orange Tip, Grass Moth, Ringlet, Small Heath, Small Tortoiseshell and Speckled Wood.

Fen vegetation in a hand cutaway bog at Lough Cara, Co. Galway. Abandoned cutaway areas, given time develop stable, species rich wetland communities. Photo: Peter Foss

Freshwater Invertebrates
Wetland habitats occurring in cutaway bogs are important refuges for freshwater snails, insects, spiders and crustaceans. Perhaps one of the more interesting groups are the spiders who have come from the land to live in freshwater. The raft spider (Dolomedes fimbriatus) was recorded on five cutaway bogs. The raft spider hunts over the floating leaves of bog pool and wetland plants, but Argyroneta aquatica is the true water spider and this was recorded on one fenland site near Lough Cara in Co. Mayo. It lives, feeds, breeds and hibernates entirely underwater. It makes webs between the stems of aquatic plants and carries air down to fill each web with a large bubble (or bell) to which it can retreat from hunting trips.

Significance of Cutaway Bogs
Our results show that cutaway bogs may come to represent very important wildlife habitats in the future, provided they are managed as refuges for wildlife, so as to enhance their biodiversity. The findings of IPCC's survey suggest that there is a need for a national survey of cutaway bogs in their own right, to identify those areas of greatest wildlife value. IPCC will be using our report on cutaway bogs to call on Dúchas to undertake such a survey in the near future.