Report on the Conservation Value of Irish Coastal Sites: Machair in Ireland
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0 REPORT OWN' TOE: CONS-ERVATEON 01IRISH. O.OA;STArL, SITE-S o MAC 1AIR ,.IN. -IRELAND* 9 BY ' NNEBASSETT- vR+,i, 1 I v REPORT ON THE CONSERVATION VALUE OF IRIS? COASTALSITES: MACHAIR IN IRELAND By ANNE BASSETT, B.A. (MOO.), H.Dip.Ed.,Dip.et. app. (Montpellier). REPORT COMPILED FOR THE DEPARTMENT OF FISHERIES ANDFORESTRY DECEMBER 1983 lit 3. I . 2 . TABLE OF I CONTENTS Ii-'TRUDUCT10N: nLCln OFTHE SCUTLAi'gD. CiiAi,:ACTEi%1STICS OF IN 1.1 Definitionof eiacnair Page No. 1.2 General 5 1.2.1 PhysicalDackyrouna 1.2.2 uistriDution 6 i . 2.3 Sol.is 7 1.2.4 Ci i,, ate r_orpnoloyy 5 1.2.5 10 12 1.3 human 1.3.1bacKground 1.3.2 ti story 13 Present DayUse -Cultivation, 13 Pasturage,,anagement II ,E` HUDS: 14 SURVEY OFIRISH MACHAIR SITES 15 2.1 General,..ethods 15 2.2 Soils 16 2.3 Climate 16 2.4 Morphology 16 2.5 Veyetation 2.6 16 humanInfluence 17 2.7 Conservation ValueAssessment III 17 RESULTS:SURVEY OF IRISH iACHAIRSITES 3.1 Soils 17 3.2 Climate 18 3.3 Morphology 20 .3.4 VeSetation 3.5 21 HUManInfluence 3.6 23 Discussion ofResults 24 IV DESCRIPTIONS ANDCONSERVATIOt4 VISITED ASSESSMENTSOFSITES 26 GeneralConclusions Bibliography 54 55 Acknowledgements J Tables 1-5 58 59 Appendices1-4 3 . TABLES, FIGURES, PLATES, APPENDICES TABLES 1 . Surt:mary A ofoccurrenceofthe com T,.on si,:eciesfoundort ti,acnair. 2. ph values, percentaue organic;,tatter,depth of humus and percentage CaC03 front 15 ii..acnair sitesin western. Ireland, c(jr:Sistiny of 34 sairil,les, ana from 4 Scottish sites. 3. _orpholoyical features noted from Irishir,achair sites. 4. Vegetation table based on 47 releves from17 raachair sites in western Ireland. 5. Archeoio:;ica features notedfrom machair sites, in tielu a.1,=froii. V'an-,.'6" Ordnance Survey 1. Locational map of Scotland. 2. Climatic data from StilligarySouth List. 3. Typical aune-machair morphological sequence in the Hebrides. 4. Climatic data from a) helmulletand o) Nalin :!ear,. Distribution of machair sites inIreland. 4 . SUMMARY .iachait is a landform-vegetationcomplex aescribea extensively iroi: where it has a north-western, Atlantic cistribution. It may also be expectedto occur in Irelandas 1_:hysicallyana climatically muchof western and north-western Irelana closely resembles those parts of Scotia, 'c: in which i,:aciiairis touna.As it is a unique lanascapein t.)e European ct-,nteat it deserves priority in research ana conservation. This report e.:iDGules the results of a survey conauctea to locate, uescrioe ana assess, from a conservation viewpoint,machair sites in Irelanu. The characteristics of machair in Scotlandare first reviewed and the generalphysical background of its distribution, soils, climate, morphology and vegetationare given. This is followed by a short account of the human use of thecomplex. The methods chosen to survey Irish sitesare outlined. Dataon soils, climate, morphology, vegetation, human influenceand conservation potential were collectedfrom 25 sites.The analyses ey data showed that machair occurs extensively in Ireland ana: that itis very similar to that described fromScotland in terns of climate, soils, morphologyand vegetation. The main difference lies in the land-use;in Ireland all machairis heavily grazed ana utilised asan amenity. Descriptions of individual sites and evaluation of their conservation value complete, the report and the general conclusions confirm thattwo sites in Co. Mayo- Dooagntry and Annagh-Termoncarragh - contain the most extensive areas of machair in Ireland and which are consequently of most valuefor conservation. l INTRODUCTION: REVIEW OF THE CHARACTERISTICS OF MACHAIRIN SCOTLAND 1.1 Definition of machair The physicalcorm of Irelandallows foran exceptional length of coastline in relation to itssurface area. Tnus, a surprising variety of coastline types occur,incluaing ::,any diverse landform ana vegetation types, compared with most other European countries. Itis with this in mind, ana Ireland's Atiantic location that the question of the occurrence or machair in Ireland is approached. Machair is a uniquecoastallandform-vegetation complex which has been extensively described from Scotlandfrom places of extreme oceanic climate with high winds. Typically a flat sandy coastal plain, morphologically wature ana stable, it arises from deposition of windblown sand which is normally rich in calcium carbonate dueto the presence ofshell fragments. Machair plains contain a characteristic type of grassland vegetation witha herb rich sward from which sand-binding speciesare virtually absent, and a landscape quality which is almost "indefinable". (Ritchie 1975). The complex is maintainedby a traditional systemof grazing on commonage strongly associated with Gaelic speaking areas, and in fact, the word "machair" isa Gaelic word meaning "plain". Dickinson (1977)regards machair as a'I socio-ecosystem", a result of the interaction ofa physical environment with the flora, fauna and human culture creating a distinctive landscape or "landschaft". In short, the following suite of attributescan be used in practice to define machair (after Ritchie, 1975). 1. Mature coastal sandy plain with more or less level surface. 2. Lime rich soil with high ph values containingshell fragments. s. Grassland vegetation with a low percentage sand-binding species. 4. it history of grazing ana hu.aan interference. 5. An extreme oceanic climate with high winds. iseorrimonlythought of as occurring only inthe nortn and west of Scotland, and in particular inthe Outer heurides. Ritchie (1975) notesthatthis is only an inuication of an overriding climaticcontrol and that similar areas in Norway, west of Irelandand parts of the coastline ofEnglandand hales have vegetation-lanuform complexes wnich could be equally regardecas "machairs". "Ithregarato Ireland, Akeroyd and Curtis(1980) have a site on the Mullet Peninsula, Mayo which they concluded was machair and indicated that other sites of this type occur in western Ireland notably inDonegal and Connemara. As is noted by Dickinson (1977), machair is .an unusualand ecologically interesting landscape in the Europeancontext and it therefore has a high clairn to priority in conservation. Thus, if Ireland holds large areas of machair it is essential that sites should be identifiedana surveyed and their conservation potential assessed. The purpose of this report, within the tune limits and resources available, is to identify, survey and assess from a conservation viewpoint the machair, sites of Ireland. 1.2 General Physical Background To make a full assessment of Irish machair sites, it is necessary that the characteristics of Scottish machair be first described against which Irish sites can ultimately be compared. ' Ni LJ r ' 1 . 7 . LI i 1.2.1 Distribution LI i r1 Aachair occurs, within the limitsof our definition, LI north and north-west in cotlana, withan exclusively Atlantic distribution. It occurs extensively in the Outerand Inner LI Hebrides (notablyon worth and South Uist ano on thenearby sh:aller islandssuch as the Monach approximately Isles) where itcovers 10% of their total area (Ritchie 1 71). Lewis and Harrishave a small extent of machair. It occurs also in theShetlands and the Orkney Islandsas well as on other highland Islands such as Islay,aura, %iull, Coll, Colonsay and Tiree(Ritchie 1975). onthe mainland, machair is found atvarious Sutherland sites in Caithness, Inverness and ivigtown (Fig. machair, 1). however cannot be considered unique to the Hebrides oreven to north and west Scotland- the term having a widerapplication and can be synonymous with "links" and"burrows"(Ritchie, 1975) in otherparts of these islands. 1.2.2 Soils The soils of the machair are probablyits most distinctive ecologicalcharacteristic, the substratenormallybeing highly calcareous(Dickinson and Randall, 1979). Generally they arecomposed of shelly sand, the quantityof whichcan be r:ore or less equated with percentagecalcium carbonate (Ritchie 1967). Single grained in texture,the soils nave a high pH,a low percentaye of organic matterand have a low fertility with most major and minorelements deficient (Dunn 1981). They are fragileand present difficulties utilisation in and conservation (Dickinson,1977). Recorded calciumcarbonate levels in the soilsof the machair of Scotlana are in the range 0-80%(Ritchie, 1971) while the mean value is 41.1% (Randall,1974). Typically, thereis. a decreasein calcium carbonate from theshore inland with the buila-up of organicmatter (Dickinson and LOCATIONAL MAP OF SCOTLAND 1; 200000SGWn Orkney '4iq OUTER HEBRIDES Caith Sutherland Monad, Isles "sINNER J Shetland J r .b. xanaall,1979), giving rise toa purer and purer quartz fraction (Ritchie, 1972). Trenas in the reauction of calcium carbonate inland are often difficult to aetect. Firstly,the rateat which calciu:u carbonate is leached,in the dune-machair system, is not known. It appears that it relates to thebuild-up of organic material, 9% ofwhich requires 300 yearsin coastal dunes (Salisbury, 1925). Secondly, the nature and source of the parent material (sand) and its distribution within the machair system varies leading to complex spatial patterns (Dickinson, 1977). Thirdly, the chemical composition of the sand at any one time appears ultimately to be related to the morphology and drainage conditions of the area (Ritchie 1972). Some machair soils stillhavea high calcium carbonate content even though they are part of a maturemorphological surface. This is accounted for by deposition of wind blown calcareous sand (Randall, 1974). Tine wind borne nature of the sand is betrayed bythesize of the grains, their unpolished surface and their well sorted nature (Ritchie, 1972). The calcareous nature of machair soils leads tohigh pH values (usually above 7.0). Randall (1974) recorded a pH C range from over 8.0 on the coast to7.2 inland for the machair on the bionach Isles,the mean value being 7.61. The pH values tended to decrease inlandwithincreasing' organic matter. The percentage organic matter in machairsoils is always low, usually less than 1LA goiny as low as 2%and below Randall (1974) recorded a mean value of I (Dickinson, 1977). 11.54% on the Monach Isles. The upper humified layer of soil which supports plant life is usuallythin - from 7-20 cm (Ritchie, 1971).