Owenirragh, Glenamoy, Co. Mayo - Blanket Bog Restoration in Ireland

Owenirragh bog, Glenamoy, Co. Mayo 

RESTORING ACTIVE BLANKET BOG IN IRELAND 

Project reference: LIFE02NAT/IRL/8490 

A REPORT ON THE RESTORATION OF PROJECT SITE No. 9. 

OWENANIRRAGH, CO. MAYO. 

Compiled by: John Conaghan 

11 Dun Ard, 

Craughwell, 

Co. Galway, 

Ireland. 

enviroscope@indigo.ie 

mhtml:file://H:\OSD Clients\Existing\Coillte - Irish Bog Restoration Project\WWW\dow... 

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Table of contents 

Page No. 

1. Introduction 3 

2. Methods 4 

3. Site Photographs 6 

4. Vegetation of the Site 11 

5. Changes in overall vegetation/habitat cover 13 

6. Monitoring quadrats 14 

References 


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Project Site No. 9 – Owenanirragh , Co. Mayo 

1. Introduction 

Grid reference 

F 937 379 

SAC Name and number 

Glenamoy Bog Complex (500) 

Area of conifer cover (ha) 

107.0 

Elevation (m) 

60 to 70 

Site area (ha) 

166.0 

Area of open bog (ha) 

46.0 

Bedrock geology 

Sandstone 

Main restoration methods 

Fell to waste of conifer crop, windrowing 

and drain-blocking. 

Area of oligotrophic lake (ha) 

13.0 

Noteworthy plant/animal species occurring 

Vaccinium oxycoccus, Eriocaulon aquaticum, Listera cordata, Juniperus communis subsp. nana 

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Owenanirragh is an isolated area of conifer plantation which lies 6 kilometres north-east of Glenamoy 

village in north-west Co. Mayo. It is one of the larger sites in the project covering an area of 166 

hectares, 107 hectares of which were planted with conifers. Much of the western half of the site lies 

within the Glenamoy Bog Complex Special Area of Conservation which is an extensive blanket bog area 

with an excellent representation of blanket bog habitats. 

Much of the afforested portion of the site comprises relatively young conifer trees under which there still 

exists a bog flora, albeit modified and rather species-poor. Two main areas of high quality, unplanted 

blanket bog also occur within the site and these contain many well developed pool systems. The intact 

bog vegetation is generally dominated by purple moor-grass (Molinia caerulea) and black bog-rush 

(Schoenus nigricans), while the blanket bog pools are characterised by a sparse flora which includes 

bog bean (Menyanthes trifoliata), many-stemmed spike-rush (Eleocharis multicaulis) and pipewort 

(Eriocaulon aquaticum). The European distribution of this latter species is confined to lakes and pools in 

lowland blanket bog areas of Ireland and western Scotland. This area of bog has also a well-developed 

Sphagnum cover including some large hummocks of Sphagnum imbricatum and S. fuscum. The site 

also contains a portion of Lougherglass, which is a medium–sized lowland oligotrophic lake. 

At this site the main restoration measures undertaken were the manual felling of the conifer crop most of 

which was subsequently wind-rowed by machine. Any significant artificial drains were blocked with 

plastic dams. 


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2. Methods 

Prior to the start of restoration activities at the site the habitats and vegetation occurring were surveyed 

and described. Habitats occurring were mapped with the aid of a vertical aerial photograph of the site 

taken in the year 2000 by the Ordnance Survey of Ireland. At the end of the project the habitats present 

were mapped with the aid of a vertical aerial photograph of the site taken between 2004 and 2006. 

The vegetation occurring at the site was described using the Zurich-Montpellier approach (Mueller- 

Dombois and Ellenberg, 1979), where the percentage cover of the various vegetation layers and plant 

species in a defined area is estimated visually. The cover of plant species in relevés was estimated in 

accordance with the Domin scale which is outlined in the table below. 

Table 1. The Domin scale of cover/abundance. 

In addition to plant species presence and cover, the following parameters were noted for each relevé: 

(1) Size 

1 =


and local context with particular emphasis on animal species listed in Annex II of the E.U. Habitats 

Directive and plant species listed in the Irish Red Data Book for vascular plants (Curtis and McGough, 

1988), the 1999 Flora Protection Order and Annex II of the E.U. Habitats Directive. 

Plant species nomenclature in this report follows Stace (1997) for vascular plant, Smith (2004) for 

mosses, Smith (1991) for liverworts and Dahl (1968) for lichens. 


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3. Site Photographs 

In order to illustrate the restoration activities which have taken place at this site a number of photographs 

are presented in the following pages. These include both aerial photographs, supplied by the Ordnance 

Survey of Ireland, and a selection of ground photographs taken by the author. 

Bog bean (Menyanthes trifoliata) is a common species of bog pools at Owenanirragh. 


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A view of the conifer crop at Owenanirragh viewed from the south, looking to the north. This photograph was taken 

only a few weeks after the start of conifer felling. Photograph taken in October 2003. 

A photograph of the site taken from approximately the same position as above, almost 4 years after tree felling. 

Note the grey windrows of conifers. Photograph taken in August 2007. 


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In the south-western portion of this site the unplanted blanket bog contains a well developed system of large 

pools. Menyanthes trifoliata is the main plant species growing in them. Note the conifer wind-rows in the 

distance. Photograph taken in August 2007. 

Bog pools within this site support populations of the rare aquatic plant species Eriocaulon aquaticum. The 


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European distribution of this species is largely confined to blanket bog pools and lakes in the west of Ireland and 

western Scotland. 


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A close-up view of wind-rowed conifers at the site with cleared bog surface visible on the left. Photograph taken in 

March 2004. 

A view of a plastic dam in a drain at the site. Note that the water level is higher on the right hand side of the dam 

which shows that water is being retained. Photograph taken in August 2007. 


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An aerial photograph of the Owenanirragh site prior to restoration work taking place. Aerial photograph taken in the 

year 2000. The site is outlined in red. Note the areas of open bog with well-developed pool systems. 

2006 Aerial photograph is not available. 


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4. Vegetation of the site 

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This site is dominated by a conifer crop which was planted in 1990. The main tree species planted was 

Sitka spruce with lodgepole pine also planted in smaller amounts. By the start of this restoration project 

in 2003 these trees had not grown to the stage where the native blanket bog flora had been completely 

killed off. Molinia caerulea and Calluna vulgaris were still common in the ground layer with mosses such 

as Hypnum cupressiforme, Rhytidiadelphus loreus and Sphagnum capillifolium also present. 

A remarkable feature of this site is the occurrence of two extensive areas of unplanted blanket bog with 

well-developed pool systems. Menyanthes trifoliata is the main species in these pools with Sphagnum 

cuspidatum, S. auriculatum, Eriocaulon aquaticum and Eleocharis multicaulis also characteristic. The 

rare shrub Juniperus communis subsp. nana was noted growing on the larger island hummocks within 

blanket bog pools and also along pool margins. The intact, undrained blanket bog vegetation itself is 

dominated by the typical blanket bog species Schoenus nigricans, Trichophorum cespitosum, Erica 

tetralix and Narthecium ossifragum. The composition of the bog vegetation is outlined in the following 

table. 

Quite a well developed bog natural drainage channel runs in a southerly direction through the middle of 

the site. Frequent plant species in this channel include Carex paniculata, Angelica sylvestris, 

Menyanthes trifoliata, Carex rostrata and Potentilla palustris. 


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Table 2. Vegetation at Owenanirragh. 

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A A A A A B B B B B C C C C C 

Quadrat code 13 8 11 3 5 2 15 6 10 7 4 9 12 14 1 

Quadrat size (m2 ) 

4 4 3 4 4 4 4 4 4 4 4 4 4 4 4 

Slope (degrees) 0 0 0 0 0 1-3 0 0 0 0 1-3 3-5 0 0 1-3 

Vegetation cover (%) 30 15 95 95 40 95 99 98 98 95 100 100 100 100 100 

Bare rock (%) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 

Bare soil (%) 0 0 0 0 10 5 1 2 2 5 0 0 0 0 0 

Surface water (%) 100 100 0 100 70 0 0 0 0 0 0 0 0 0 0 

Dwarf shrub cover 0 0 0 0 0 50 40 50 45 55 40 70 60 10 40 

(%) 

Herb cover (%) 30 15 40 15 35 70 60 65 60 60 65 40 50 95 70 

Bryophyte cover (%) 0 0 95 95 12 70 50 60 70 40 35 50 5 15 5 

Ht. of vegetation 10 15 10 5 8 10 10 15 10 15 35 35 40 35 30 

(cm) 

No. of species 1 2 5 6 6 22 21 20 19 16 12 12 7 6 6 

Menyanthes trifoliata 6 4 5 4 . . . . . . . . . . . 

Eriocaulon 

. 5 . . . . . . . . . . . . . 

aquaticum 

Sphagnum 

. . 9 9 3 . . . . . . . . . . 

cuspidatum 

Eleocharis 

. . 5 2 5 . . . . . . . . . . 

multicaulis 

Sphagnum 

. . 2 4 5 . . . . . . . . . . 

auriculatum 

Schoenus nigricans . . . 1 . 3 5 5 5 5 . . . . . 

Narthecium 

. . . . . 4 4 3 4 4 . . . . . 

ossifragum 

Racomitrium 

. . . . . 2 5 5 5 5 . . . . . 

lanuginosum 

Sphagnum tenellum . . . . . 2 4 3 4 4 . . . . . 

Eriophorum 

. . . . . 4 5 4 4 . . . . . . 

vaginatum 

Cladonia uncialis . . . . . 3 1 4 4 . . . . . . 

Pleurozia purpurea . . . . . 5 5 5 5 . . . . . 

Odontoschisma 

. . . . . 2 3 3 3 . . 2 . . . 

sphagni 

Drosera rotundifolia . . . . . 2 1 1 1 . . . . . . 

Trichophorum 

. . . . . 4 3 . 2 4 . . . . . 

cespitosum 

Rhynchospora alba . . . . 1 . 3 2 . 3 . . . . . 

Sphagnum 

. . . . . 3 . . . 3 . . . . . 

papillosum 

Eriophorum 

. . 4 1 4 5 4 4 5 4 . . . . . 

angustifolium 

Molinia caerulea . . . . 3 6 6 7 7 7 8 7 7 10 8 

Calluna vulgaris . . . . . 5 5 5 5 6 6 8 8 3 7 

Potentilla erecta . . . . . 3 2 2 2 3 2 2 3 1 2 

Sphagnum 

. . . . . 7 4 4 3 4 . 5 3 4 4 

capillifolium 

Erica tetralix . . . . . 5 5 6 6 6 1 4 2 . 2 

Hypnum 

. . . . . 4 3 2 4 . 5 5 3 4 . 

cupressiforme 

Erica cinerea . . . . . 3 2 4 3 . . 5 1 4 4 

Cladonia portentosa . . . . . 6 6 5 7 5 4 6 . . . 

Polygala serpyllifolia . . . . . . . 1 . 3 . 1 . . . 

Pleurozium schreberi . . . . . . . . . . 3 1 . . . 

Carex panicea . . . . . 4 . . . . . . . . . 

Leucobryum glaucum . . . . . 1 . . . . . . . . . 

Succisa pratensis . . . . . 1 . . . . . . . . . 

Campylopus 

. . . . . . 1 . . . . . . . . 

atrovirens 

Dicranum scoparium . . . . . . . . . . 2 . . . . 

Dryopteris dilatata . . . . . . . . . . 2 . . . . 


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Rhytidiadelphus . . . . . . . . . . 2 . . . . 

loreus 

Saccogyna viticulosa . . . . . . . . . . 1 . . . . 

Salix aurita . . . . . . . . . . 1 . . . . 

Campylopus 

. . . . . . . . . . . 2 . . . 

introflexus 

A = Blanket bog pools 

B = Intact blanket bog dominated by Schoenus nigricans and Molinia caerulea 

C = Drained blanket bog dominated by Molinia caerulea 


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5. Changes in overall vegetation/habitat cover 

This site is now characterized by regenerating lowland blanket bog, dominated by Molinia caerulea, with 

numerous rows of felled conifers. In three small areas the trees were not windrowed for experimental 

purposes and Molinia is also attaining dominance in these. There has been little observable change in 

the open bog areas as they were not subject to any restoration work. 

A map of habitat/vegetation cover at Owenanirragh prior to the start of restoration. 


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A map of habitat/vegetation cover at Owenanirragh prior at the end of restoration. 

6. Monitoring quadrats 

In the following pages the vegetation changes which have taken place within the site over the period of 

the restoration project are shown by means of observed changes in permanent quadrats. A total of 6 

permanent quadrats were described and photographed. In the case of each quadrat photographs and 

vegetation tables are presented. In order to ensure the future relocation of quadrats the corners have 

been marked with short sticks and a 10-figure GPS reading was also recorded. The cover of plant 

species within the quadrats is presented in accordance with the scale outlined in the following table. 

Cover of species in quadrat Cover in presented quadrat tables 

75% cover of the species in most areas within 3 

years. The other main recolonizing species are Hypnum cupressiforme, Campylopus sp., Calluna 


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vulgaris, Sphagnum capillifolium, Polytrichum commune and Potentilla erecta. 

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In areas of the site where a cover of taller lodgepole pine trees was felled and windrowed the bog 

vegetation was largely killed off by the deposition of a layer of pine needles (see permanent quadrat 4 

and 5). Although Molinia is also frequent in these areas the recovery of vegetation has been slower with 

a high cover of disturbed peatland species, e.g. Campylopus sp., and Epilobium angustifolium, evident. 


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Quadrat 1 – July 2004 

Quadrat 1 – August 2007 


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Site - Owenanirragh 

Code - PQ1 

GPS – F 93981 37415 

Near Walrag? - No 

Size (m) – 8x8 

Slope (Degrees) – < 5 

Vegetation cover (%) 70 80 98 

Needle litter cover (%) 30 20 0 

Bare soil (%) 30 3



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Code – PQ2 

GPS – F 93889 37739 






Bare soil (%) 5 0 0 

Vegetation height (cm) 30-40 40 to 50 40 to 50 

Dwarf shrub cover (%) 3 8 10 

Herb cover (%) 75 95 98 

Bryophyte cover (%) 30 35 50 

No of species present 15 18 22 

Date of survey 23/7/04 16/8/05 8/8/2007 

Molinia caerulea 6 7 7 

Hypnum cupressiforme 4 4 5 

Sphagnum capillifolium 3 2 3 

Calluna vulgaris 2 3 3 

Polytrichum commune 2 2 3 

Potentilla erecta 2 2 2 

Rhytidiadelphus loreus 2 1 3 

Agrostis sp. 1 2 2 

Campylopus introflexus 1 2 3 

Erica tetralix 1 2 2 

Dryopteris dilatata 1 1 1 

Epilobium angustifolium 1 1 3 

Epilobium sp. 1 1 1 

Dicranum scoparium 1 - 1 

Leucobryum glaucum 1 - - 

Erica cinerea 1 1 

Hylocomium splendens 2 3 

Hypochoeris radicata 1 - 

Polygala serpyllifolia 1 1 

Rumex acetosa 1 1 

Rhytidiadelphus squarrosus 3 

Eurhynchium praelongum 3 

Angelica sylvestris 1 

Cladonia sp. 1 

History – Previously dominated by a young Sitka spruce plantation planted in 

1990. Trees were generally between 4 and 7 metres tall. Ground 

vegetation was dominated by a sparse growth of purple moor grass and 

scattered mosses (mainly Hypnum cupressiforme). Trees felled to waste 

in early 2004. 


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GPS – F 93852 38066 



Slope (Degrees) – 0 



Cut stumps (%) 2 0 0 

Vegetation height (cm) 40-50 40-50 40 to 60 

Dwarf shrub cover (%) 60 60 50 

Herb cover (%) 40 40 45 

Bryophyte cover (%) 20 25 30 

No of species present 9 9 8 

Date of survey 23/7/04 16/8/05 8/8/2007 

Calluna vulgaris 6 6 6 

Molinia caerulea 5 5 5 

Hypnum cupressiforme 4 4 4 

Sphagnum capillifolium 2 3 3 

Rhytidiadelphus loreus 2 2 2 

Potentilla erecta 1 2 2 

Cladonia portentosa 1 1 - 

Erica tetralix 1 1 - 

Aulocomium palustris - 1 - 

Dicranum scoparium 1 - - 

Pleurozium schreberi 1 

Liverwort species 1 

History – Previously dominated by a young Sitka spruce plantation planted in 

1990. Trees were generally between 4 and 7 metres tall. Ground 

vegetation was dominated by heather and purple moor grass. Trees felled 

to waste in early 2004. 


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GPS – F 93460 38014 







Vegetation height (cm)



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GPS – F 93039 37750 



Slope (Degrees) – 5 to 15 




Vegetation height (cm)





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Area with heavy cover of lodgepole pine felled in 2004. No permanent quadrat recorded. Note 

breakdown of conifers and emergent Molinia caerulea. 


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REFERENCES 

Curtis, T.G.F. & McGough, H.N. (1988). The Irish Red Data Book. 1: Vascular Plants. The Stationery 

Office, Dublin. 

Dahl, E. (1968). Analytical Key to British Macrolichens (2 nd ed.). British Lichen Society, London. 

Mueller-Dombois, D. & Ellenberg, H. (1974). Aims and Methods in Vegetation Ecology. Wiley, New 

York. 

Smith, A.J.E. (2004). The Moss Flora of Britain and Ireland (2 nd edition). University Press, Cambridge. 

Smith, A.J.E. (1990). The Liverworts of Britain and Ireland. University Press, Cambridge. 

Stace, C. (1997). New Flora of the British Isles (2 nd edition). University Press, Cambridge. 


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Owenirragh, Glenamoy, Co. Mayo - Blanket Bog Restoration in Ireland

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