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The conservation value of cut-away bog Lough Boora Parklands - a case study

Cut-away bog refers to land left after the cessation of large-scale industrial peat extraction from raised bogs. Species lists collected from the Lough Boora Parklands suggest that cut-away habitats, although quite different from the original raised bog, can make a significant contribution to nature conservation.

The Lough Boora Parklands comprise about 2,000 ha of cut-away bog on Bord na Móna lands, situated half-way between Tullamore, Co. Offaly and the River Shannon. The name Lough Boora links the Parklands to the well-known Mesolithic site with its ancient storm beach which lies within its boundaries (Mitchell 1997). The Parklands began as a pilot area by Bord na Móna for integrated land-use on cut-away bog (Egan 1998, 1999). In particular, the Parklands are now seen as a show-case for tracing the progress of natural re-colonisation of cut-aways.

This report is based on a survey which described these re-colonising habitats, evaluated their conservation interest and suggested a nature conservation designation (Heery 1999). One criterion, among many, for assessing the conservation interest of a site is the presence of rare, scarce or local species (An Foras Forbartha 1981; Ratcliffe 1977). For this survey, species lists were made by specialists in various species groups (see Acknowledgements) namely, Odonata (dragonflies and damselflies), Coleoptera (rove and ground beetles), Lepidoptera (moths and butterflies) and lichens. New and unpublished data on birds and vascular plants were also used.

Before large scale, mechanical harvesting began in the 1940s the bogs at Boora probably had all the ecological features and suites of species of raised bogs. The expanse was probably one of the largest in existence at the time and was very much larger than any existing pristine raised bogs. A reminder of the suite of species which once occurred in the Boora landscape was found on a small remnant of raised bog on the edge of the Boora Complex. Here Cranberry Vaccinium oxycoccos, Bog Rosemary Andromeda polifolia, Round-leaved Sundew Drosera rotundifolia and Fir club moss Huperzia selago grow accompanied by five bog mosses (Sphagnum magellanicum, S. papillosum, S. capillifolium, S. subnitens and S. cuspidatum) and the bog liverworts Pleurozia purpurea and Odontoschisma sphagni. The Black Darter Sympetrum danae, a dragonfly of acid Sphagnum pools, was also found.

Production ceases on the bogs for a variety of reasons: the stumps of fossil forests impede the milling process; the sub-peat surface is reached over parts of the field so that white marl mixes with the milled peat; sub-surface ridges of esker gravels or bedrock are reached; extraction goes below the permanent water-table and drainage become an insurmountable problem. All these factors result in differences in peat depth and type, soil type and drainage characteristics of the cut-aways, often apparent over small distances. These differences have determined the final options for land-use in the Parklands. Agricultural grassland has been successfully established where less than one metre of fen peat overlies mineral soil. Forestry establishment has been less successful due to frost damage, hare damage and competition with re-colonising plant species such as Soft rush Juncus effusus and Rosebay Willowherb Epilobium angustifolium (Jones 1998).

A third land-use option is wetland creation and natural re-colonisation. These are the habitats dealt with in this chapter. Where the sub-surface contours indicate a natural hollow the peat type is usually reed peat overlying lake deposits - white marl or grey clay. Between 1990 and 1999 almost 300 ha of wetlands were created in these circumstances at eight individual sites by embanking and / or blocking drains. The majority were less than three years old at the time of the survey, although the Turraun wetland was created in 1991. Since 1999, another wetland of almost 100 ha has been created and others are planned.

Birds
The Grey Partridge Perdix perdix is on the verge of extinction in Ireland and Boora may have the last remaining wild population. In 2000 there were probably less than eight breeding pairs (Kavanagh 2001). The most suitable habitat for breeding Partridge is dry cut-away bog with exposed marl and little peat. These areas become vegetated with a suite of colonising wild flowers and grasses, which in turn support a high density of insects which are the primary food of young Partridge chicks. Two hundred hectares of such land in the Parklands is now being developed as a Partridge breeding management project.

Breeding waders began to breed at the new wetland sites immediately after their creation. Between 30-50 pairs of Lapwing Vanellus vanellus nested annually in the Parklands from 1998 to 2000. The Lapwing is a 'Red Species' on the list of birds of conservation concern (Newton et al 1999) because breeding numbers are suspected as being in serious decline in Ireland. Redshank Tringa totanus, Ringed Plover Charadrius hiaticula, Common Sandpiper Actitis hypoleucos and Common Snipe Gallinago gallinago all nest in the Parklands. Ringed Plover is predominantly a coastal nesting bird.

Eight species of waterfowl breed in the Parklands wetlands. The populations of some species have been particularly high. Nineteen pairs of Tufted Duck Aythya fuligula produced about 120 young in 2000. A post-breeding population of over 100 Little Grebes Tachybaptus ruficollis occurred in 1999. Thirty is the threshold for All-Ireland importance for Little Grebes (Colhoun 2001). Four pairs of Great Crested Grebes Podiceps cristatus bred in 2000 in the newest wetland. The presence in summer of Pochard Aythya ferina, Shoveler Anas clypeata and Wigeon Anas penelope in the past few years may herald future breeding of these scarce ducks.

Three species listed in Annex 1 of the E.U. Birds Directive have been regular in the Parklands. Whooper swan Cygnus cygnus occurred in numbers of All-Ireland importance (i.e. >100) in all but one winter from 1992 - 2000. A female Hen Harrier Circus cyaneus has roosted in suitable breeding habitat the Parklands each summer since 1997. This species was still nesting on Boora bog in the late-1960s (Sharrock 1976). A pair of Merlins Falco columbarius has bred in and around the Parklands for at least a decade.

The overland passage of wading birds during migration is not as well known as at coastal sites because of the smaller numbers involved and the dispersed nature of suitable feeding sites. In the past five years, however, the following long list of waders has been recorded on passage at these new wetlands (Heery 2000).

Oystercatcher Haematopus ostralegus	Ringed Plover Charadrius hiaticula
Golden Plover Pluvialis apricaria	Grey Plover Pluvialis squatarola
Knot Calidris canutus	Sanderling Calidris alba
Little Stint Calidris minuta	Temminck's Stint Calidris temminckii
Dunlin Calidris alpina	Ruff Philomachus pugnax
Black-tailed Godwit Limosa limosa	Whimbrel Numenius phaeopus
Spotted Redshank Tringa erythropus	Greenshank Tringa nebularia
Green Sandpiper Tringa ochropus	Common Sandpiper Actitis hypoleucos

In addition, American Golden Plover Pluvialis dominica and Wood Sandpiper Tringa glareola have occurred at a similar cut-away wetland close-by at Bord na Móna's Blackwater Works, Shannonbridge. New insights have been gained by frequent watching. One has been the regular autumn passage of Ringed Plovers (a flock of 39 in August 1999; a total of 77 passing through one wetland from July to September 2000).

Vascular plants
The cut-away habitats in the Parklands are providing valuable refuges for plant species from many habitats in West Offaly and often from further afield. Many of the aquatic plants are likely to have re-colonised from the rich reservoir of species present in the surrounding drains.

About 210 vascular plant species had been recorded within the Parklands up to 1999 and there are probably new species immigrating continually. For instance, new individuals of Royal Fern Osmunda regalis and Fir Club-moss Huperzia selago were found together on recently abandoned peat at one location. Buried eskers and limestone outcrops have been exposed in many parts of the Parklands. The colonising suite of species resembles those of species-rich esker grasslands, including Yellow Centaury Blackstonia perfoliata, Mountain Everlasting Antennaria dioica, Mouse-ear Hawkweed Hiercacium pilosella and, more notably, Autumn Gentian Gentianella amarella, Field gentian Gentianella campestris, Goat's Beard Tragopogon pratensis and heath Dog-violet Viola canina. Plant species which are considered to be scarce in the centre of Ireland have found widespread niches on shallow peat in the Parklands. Creeping Willow Salix repens, Red Centuary Centaurium erythraea and Heath Groundsel Senecio sylvaticus are examples of these. In addition, plant species which have a more coastal distribution in Ireland have been found at Boora. Broom Cytisus scoparius, Dark-green Mouse-ear Cerastium diffusum and, most notably, Sheep's Bit Jasione montana are examples of these. A population of Marsh Helleborine Epipactis palustris totalling over 1,000 spikes occurs on damp gravel at one of its locations in the Parklands. Three species of Bladderwort, insectivorous aquatic plants, are present in the Parklands, namely Greater Bladderwort Utricularia vulgaris, Intermediate Bladderwort U. intermedia and Lesser Bladderwort U. minor, reflecting the general diversity of aquatic plants.

Lichens
About half of the 39 species of lichens and two species of lichenicolous fungi collected during one day at Turraun had probably colonised from the surrounding areas as the peat was being worked. The rest were those that had persisted in undisturbed corners of milled-peat fields. The list was composed entirely of ruderal (pioneering) species which are widespread in the West Offaly landscape. The majority are present in esker grasslands and birch woodlands. The bare peat surface amongst grass had six species, all Cladonia spp. Some were typical of raised bog, such as C. fimbriata, C. furcata and C. crispata cetrariiformis, while others were typical of esker grassland, such as C. rangiformis and C. pocillum. Exposed limestone rock held fifteen species of a typical calcicole assemblage including, for instance Bacidia sabuletorum, Catillaria lenticularis and Clauzadea immersa.

The stumps of fossil bog wood (lignum), either in situ on the peat surface or piled up during preparations for harvesting, are a habitat unique to cut-aways. Although very small in area they held ten species, five of which were Parmelia spp. Most were considered to be locally relict species derived directly from lichen populations of epiphytic niches on heather, birches and willows which were present before peat extraction.

Dragonflies and damselflies
West Offaly, and central Ireland east of the River Shannon, has a paucity of small shallow water-bodies and the new wetlands in the Parklands are a significant addition to this habitat.

Dragonflies and damselflies need water in which to breed and favour aquatic sites with clean unpolluted water, open to sunlight yet sheltered from strong winds, with plenty of aquatic vegetation, rushes and sedges along the margins (Merritt 1985). Moore (1987) has illustrated that dragonflies can quickly colonise new areas of suitable habitat.

Nine species were identified (all adults, seven in the hand) at three wetland cut-away sites on one day in August 1999 - the Common Darter Sympetrum striolatum, the Four-spotted Chaser Libellula quadrimaculata, the Common Blue Damselfly Enallagma cyathigerum, the Blue-tailed Damselfly Ischnura elegans, the Large Red Damselfly Pyrrhosoma nymphula, the Emerald Damselfly Lestes sponsa, the Brown Hawker Aeshna grandis and the Keeled Skimmer Orthetrum coerulescens. One individual of the Banded Demoiselle Calopteryx splendens was also seen. The richest site (Finnamores) had eight of these species. This is a developing fen with exposed marl and a rich shallow water plant community including abundant Fen Pondweed Potamogeton coloratus and Lesser Bladderwort, and carpets of Articulated Rush Juncus articulatus. In addition to the above, the Black-tailed Skimmer Orthetrum cancellatum had been identified at Turraun in 1995 (Trodd 1995).

The presence of the Keeled Skimmer and the Black-tailed Skimmer is of special note. These two blue dragonflies have opposing habitat requirements and are both described as being local in Ireland by Merritt (1985). The Black-tailed Skimmer is generally known as a species of marl lakes and is well known from the Burren. It is also known to colonise new suitable habitats quickly (Merritt 1985). The Keeled Skimmer, on the other hand, is a species of more acid environments (and bog flushes with willows) and its main known distribution in Ireland are the blanket bogs of Kerry, Connemara and Wicklow.

Moths and butterflies
A survey of night-flying moths was carried out in less than ideal weather conditions on three nights in mid-July and late-August. In view of this, the total of 77 species recorded was considered quite high. Fifteen extra species were recorded by Trodd (1995). The large number of local species is a further indication of the entomological value of the sites. Furthermore, records of Marsh Fritillary Euphydryas aurinia and Dark Green Fritillary Speyeria aglaja butterflies substantially increase this value.

Eleven species were to some degree local and worthy of special mention.Three of these were wetland species - Pseuopostega crepusculella, Coleophora taeniipennella and Witlesia pallida. Two species were associated with well-established birch - Parornix betulae and Pebble Hook-tip Drepana falcataria. The remaining six were species of unimproved grasslands.

Twelve species butterfly were recorded (including those recorded by Trodd in 1995).
The Marsh Fritillary was collected in 1995 (Trodd 1995). This is listed on Annex II of the E.U.Habitats Directive. Although it has not been seen since, there is a breeding colony ten kilometres away and the species is known to wander. Therefore, future colonisation of the Parklands is a possibility. The Dark-green Fritillary was recorded in 1995 and seen again in 1999. It is a highly localised butterfly in Ireland, almost confined to certain coastal areas. It is rarely found inland where it occurs mainly in open areas of unimproved grassland.

Beetles
Rove beetles and ground beetles are carnivorous insects widely used in land-use impact monitoring. A total of 64 species were collected from Turraun, the oldest wetland. Two of these, Carabus clatratus and Philonthus fumarius, are regarded by entomologists as indicators of a good, well-developed habitat. By 'well-developed' is meant that the ecosystem has been sufficiently re-colonised by soil fauna so that it contains many habitat specific species characteristic of a natural wetland. A large number of other species were typical of peat wetlands, though there were no Sphagnum bog fauna. The suite of species collected at the younger site was less in number but still indicated that the soil fauna re-colonisation was progressing rapidly.

Naturalness
It is evident that the habitats of the Parklands are highly modified by humans: stripping of the peat; embanking; reseeding; and afforestation all feature prominently over the Parklands as a whole. However, re-colonisation by native species of the region is occurring and they are being allowed to interact with minimum interference by humans. This is the basic definition of 'semi-natural' vegetation, first espoused by Tansley (1965) and later by Radcliffe (1977).

Special interest
Three 'special interest' aspects increase the conservation value of the habitats in the Parklands.

1. The Parklands contain a set of semi-natural habitats developing on the internationally rare environment of cut-away bog.

2. The habitats are easily accessible for monitoring and research purposes.

3. The exposure of sub-peat surfaces (including rock outcrops and glacial debris), the exposure of fossil forests and the presence of 'ochre mounds' (fossilised accumulations of iron ore formed by specialised bacterial activity)(Feehan 1999) can be considered as significant geomorphological interest.

Conclusion
Species lists such as these are only part of the assessment and maintenance of the conservation value of a site. The evidently high species diversity coupled with the presence of many scarce and local species at the Lough Boora Parklands indicate that cut-away habitats can make a significant contribution to nature conservation. It is also evident that wetland creation is an important element in this. In contrast to raised bogs, the habitats on cut-away bogs are young, rapidly changing and increasing in area. They are a new and fertile field for research into species distribution, ecological processes and ecological management for nature conservation.

References
An Foras Forbartha (1981) Areas of Scientific Interest in Ireland. An Foras Forbartha, Dublin.
Colhoun, K. (2001) I-WeBS Report 1998-1999. BirdWatch Ireland, Dublin.
Egan, T. (co-ordinator) (1998) The future use of cut-away bogs. Proceedings from the first comprehensive conference on cut-away bogland rehabilitation. Lough Boora Parklands, Boora.
Egan, T. (1999) A Landscape Uncloaked. In: Policies and Priorities for the Irish Landscape. 119 ­ 134. Proceedings of a Heritage Council Conference, Tullamore, 1999.
Feehan, J. (1999) Bog water. Scéal na Móna: 13 (26): 24-25
Heery, S. (1999) Lough Boora Parklands ­ Habitat survey and conservation evaluation.Unpublished report to the Lough Boora Parklands Group, Bord na Móna, Boora.
Heery, S. (2000) Birds in Central Ireland - Second mid-Shannon Bird Report 1996 - 1999. BirdWatch Ireland, Dublin.
Jones, S. (1998) Forestry on milled peat cut-aways. In: (co-ordinator) Egan, T. Proceedings from the first comprehensive conference on cut-away bogland rehabilitation. 22 ­ 26. Lough Boora Parklands, Boora.
Kavanagh, B. (2001) Bird on the brink. Wings (BirdWatch Ireland) 20: 16-17.
Merritt, R. (1985) The Dragonflies of Great Britain and Ireland. Harley Books, Colchester.
Mitchell, F., Ryan, M. (1997) Reading the Irish landscape. Town House, Dublin
Moore, N.W. (1987) The Bird of Time. Cambridge University Press.
Newton, S., Donaghy, A., Allen, D., Gibbons, D. (1999) Birds of Conservation Concern in Ireland. Irish Birds 6: 333-344.
Ratcliffe, D.A. (1977) A Nature Conservation Review. Cambridge University Press.
Sharrock, J.T.R. (1976) Atlas of Breeding Birds of Britain and Ireland, 1969-71. British Trust for Ornithology.
Tansley, A.G. (1965) The British Isles and their Vegetation. Cambridge University Press.
Trodd, W. (1995) Preliminary Insect Study for Turraun Nature Reserve. Unpublished report to Bord na Móna.

Acknowledgements
I thank the Heritage Council for funding the survey, Kathryn Finney for assisting with data collecting and Tom Egan, Gerry McNally and Bord na Móna for assistance throughout. I acknowledge and thank the following specialists for their species lists and assessments during the survey: Michael Quirke (dragonflies and damselflies); Howard Fox (lichens); Ken Bond (moths and butterflies); Jervis Good (rove beetles and ground beetles) and Petra Mair (mosses and liverworts). Botanical information was taken from existing species lists held by the Lough Boora Parklands Group with additional species recorded by Robert Rowlands and the author. Dermot Breen was responsible for most of the bird records; I thank Brendan Kavanagh for information on the Grey Partridge. I also acknowledge the late Freda Rountree for her driving interest in the project. An account of this project first appeared in Scéal na Móna 13 (31).

Copyright Stephen Heery