The Vegetation, Ecology and Conservation of the Lough Oughter

T1 IL, V (11-:'A T 11 I' br 1909 pr-pared by Di` Jolun C0na1an., Cvl i_1alIl Darn, r_-talb4 1Y 11 TABLE OF CONTENTS ABSTRACT ACKNOWLEDGEMENTS Page No. CHAPTER 1 - INTRODUCTION TO THE SURVEY 1.1 Introduction 1.2 Location and extent of the survey area 1 1.3 Geology, topography and soils 1 1.4 Climate 2 1.5 Land use 2 1.6 Importance of the site 3 1.7 Structure of the report 6 CHAPTER 2 - METHODS 2.1 Vegetation recording and mapping 7 CHAPTER 3 - VEGETATION DESCRIPTION 3.1 Introduction 9 3.2 Aquatic and species-poor swamp communities 11 3.2.1 Potamogeton lucens community 12 3.2.2 Littorella uniflora luncus articulatus community 13 3.2.3 Nuphar lutea community 14 3.2.4 Schoenoplectus lacustris community 15 3.2.5 Persicaria amphibium community 16 3.2.6 Menyanthes trifoliata community 17 3.2.7 Equisetum fluviatile community 18 3.2.8 Rumex hy&olapathum community 19 3.2.9 Lychnis fibs-cuculi - Lysmachia vulgaris community 20 3.2. 10 Phragmites australis community. 21 3.2. 11 Carex elata community 23 3.2.12 Carex rostrata community 24 3.2.13 Typha latifolia community 25 3.2.14 Sparganium erectum -A lisma plantago-aquatica community 26 3.2.15 Glyceria maxima community 27 3.2.16 Glyceria fluitans community 28 3.2.17 Eleocharis acicularis community 29 3.3 Species-rich swamp communities 30 3.3.1 Eleocharis palustris community 31 3.3.2 Carex vesicaria community 32 3.3.3 Phalaris arundinacea community 34 3.4 Wet grassland and tall-herb fen communities 36 3.4.1 Carex nigra - Potentilla anserina community 37 3.4.2 Juncus effuses - Senecio aquaticus community 39 3.4.3 Filipendula ulmaria community 41 3.4.4 Iris pseudacorus community 43 3.5 Base-rich fen communities 45 3.5.1 Juncus inflexzcs - Ranunculus acris community 45 3.6 Dry and damp grassland communities 47 3.6.1 Anthoxanthum odoratum - Vicia sepium community 48 3.6.2 Alopecurus pratensis community 49 3.6.3 Poa pratensis-Trifolium repens community 50 .3 .6.4 Carex hirtacommunity 52 .3 6.5 Dactylis glomerata - Festucarubra community 53 3.7 Woodland and Scrub Communities 55 3.7.1 Salix cinerea Alnus glutinosa Filipendula ulmaria community 56 3.7.2 Fraxinus excelsior - Geum urbanum - Primula vulgaris community 59 3.7.3 Betula pubescens community 61 3.7.4 Prunus spinosa - Crataegus monogyna community 62 3.8 Overview of the flora of the site 63 3.9 Sites within the survey area of exceptional ecological/botanical interest 64 3.10 Observations of animals made during the survey 66 3.11 Discussion of survey results 67 I CHAPTER 4 ENVIRONMENTAL PROBLEMS AND POSSIBLE CONSERVATION MEASURES 4.1 Introduction 69 4.2.1 The eutrophication problem 69 4.2.2 Water quality of the Lough Oughter lake Complex 71 4.2.3 Measures to improve water quality within the site 72 4.3 The value of the natural history interest of theLough Oughter Complex 74 REFERENCES 75 Appendix 1 - Number, name and grid reference of vegetationsampling sites Appendix 2 - List of vascular plants, mosses and liverwortsfrom the Lough Oughter Complex Appendix 3 - Species of one occurrence omitted from Table16 ABSTRACT The lakes of the Lough Oughter system constitute the best-developedarea of inter-drumlin lakes in the country.The system is essentially a continuation of the Eme systemof Co. Fermanagh and consists of numerous, narrow, interlinked waterbodies which are separated byelongate chains of low hills derived from glacial material.These lakes are one of the most important coarse angling fisheries in the country and attract thousands of anglers fromBritain and continental Europe each year. In addition to the recreational and tourism value ofthe site, the lakes and their flooded margins are an important natural history resource, supporting well-developed communities ofplants and animals. The composition and ecology of many of these plantcommunities are described in this report. The semi-natural and natural vegetation associated with the margins oflakes was investigated at 56 locations within the survey area. Although many of the plantcommunities recorded are common and widespread throughout Ireland a number of communities that are eitherrare or underreported have been identified.One particularly noteworthy vegetation type is a species-rich fen community dominated by Juncus inj7exus, which does not appear to havebeen formally recorded in Ireland until now. In addition to the description of plant communities, stationsfor a number of nationally rare plant species such as Prunus padus, Equisetum variegatum and Epipactispalustris were located. Undoubtedly the most serious threat facing the site at presentis the reduction in water quality in many of the lakes within the site.This reduction in water quality has been taking place forat least the last 30 years and is primarily due to theintensive cattle-based agricultural activities in the surrounding land. Unless the problem of eutrophication is addressed, thispollution will continue to have a negative effect on the aquatic plant and animalcommunities within the site. ACKNOWLEDGEMENTS This study would not have been possible without the generousfunding of a Wildlife Grant from the Heritage Council. Much credit is due to the Council forits fostering and support of research into the rich natural heritage of Ireland. Particular thanks are due toDr. Liam Lysaght for the overseeing and encouragement the study.I am also indebted to my family, Karen and Liam,for their constant support and assistance throughout the year. 1 CHAPTER I INTRODUCTION TO THE SURVEY 1.1 Introduction The Lough Oughter Lake Complex is a veryimportant area of lakes and wetlands situated in 'Co. Cavan. Up until recently the natural history ofthe site has received little study and this is especially true of the vegetation of the site. This survey,which was made possible by the funding of a Heritage Council Wildlife Grant, aims to redress this imbalanceby documenting the vegetation of the site. The quality and conservation of the site isinvestigated and this report will also outline ways in which the natural history of the site can be promoted. 1.2 Location and extent of the survey area Lough Oughter (Grid ref. H 3 0) and its extensivenetwork of associated lakes, is located in the north of Co. Cavan, close to the border with Co.Fermanagh.The survey area occupies an area of approximately 80 km2, is diamond-shapedin outline and is delimited by the main roads which connect Cavan to the east, Belturbet tothe north and Killeshandra to the west (see Figure1). For conservation purposes the National Parks andWildlife Service, Dachas have grouped most of the lakes in this area into one large site and havenamed it The Lough Oughter Complex, a name that will be used frequently throughout this report.The Lough Oughter Complex is essentially a continuation of the extensive Upper Lough Erneand comprises a landscape dominated by low hills and lakes. Many of these lakes areinterconnected by narrow channels and/or slow-flowing rivers (Plate 1). In addition to the serpentine LoughOughter, other moderately sized lakes occurring within the survey area include Lough Inchin,Inishmuck Lake, Annagh Lough, Derrybrick Lough and Drumanny Lake. 1.3 Geology, topography and soils Sedimentary rocks largely dominate thebedrock geology of the survey area. Throughout most of the survey area limestoneand shale of the Ballysteen formation is thedominant bedrock (Geraghty, 1997), while mudstones and shales are dominantin the northeast of the survey area, to the westand Plate 1. An aerial photograph of the southern section ofthe site near Killykeen, taken from a height of approximately 6700 metres.Note the interconnection of the many lakes in the photograph. C' \ Lot!C1\igh,.I Cavan Town % ° ad A v 0 A e Killykeen a E 9 40 9 Derries Lower (a, I a A a 9 1 11 6 v 0 Q 0" 1 m o O le the extensive network ofinterconnected lakes. Figure1. A map of the survey area showing Vegetation sampling sites are indicatedby the solid triangles. Not allroads are shown. i north of Butlersbridge. As ice-sheets retreated from the area afterthe last glaciation large amounts of glacial till were deposited and this process has givenrise to an undulating landscape of large drumlins and moraines. These glacial deposits now typically form lowelongate hills, the summits of which reach an altitude of between 70 and 90 metres,a mere 30 to 50 metres above the level ofthe intervening lakes. An extensive network of lakes and rivers ofwhich Lough Oughter is the most prominent now occupies the inter-drumlin hollows. The soil of thestudy area can be described as a I clayey till (Geraghty, op. cit.) which, at least on thebetter-drained slopes, has given rise to relatively good quality agricultural land. 1.4 Climate In the context of the island of Ireland the climateof the study area can be summarised as relatively dry with warm summers and cool winters.The closest weather station to the site is situated at Clones, a mere 25km to the northeast. The mean Januarytemperature at Clones (1951 to 1980) was 3.70C, while the mean July temperature (1951 to 1980)was 14.4° C (Rohan, 1986). In comparison to other areas of the country air frosts are common atClones occurring, on average, 47 days per annum. The average yearly rainfall at Clones in the period 1951to 1980 was 917mm per annum, falling on 164 days of the year, with April and December beingthe driest and wettest months respectively. Wind at Clones comes mostly from a southwesterly or southerlydirection and the mean average wind speed is 4.4 metres per second, which is typicalof midland areas of Ireland.

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