4. Agricultural Impacts on Biodiversity and Natural Resources in Ireland

Introduction

It is the aim of this chapter to identify the impact of agricultural practices and agricultural structural change in Ireland on biodiversity and natural resources. The various aspects of structural change in the sector have been described in the previous chapter. The complexity of the influences of agricultural policy on farming practices and farmers' decision-making in response to economic signals make it immensely difficult to assign the observed changes in the rural landscape to particular agricultural schemes or payments (see Buckwell, 1989). There is a paucity of baseline information on biodiversity and natural resources and an absence of monitoring programmes specifically designed to assess the impacts of agricultural practices on the environment. This situation often only allows for very broad conclusions about the impacts of agriculture to be made.

Agricultural land use has helped to shape the Irish countryside for thousands of years. Indeed, human interference with the natural vegetation has been so extensive that it can be difficult to distinguish entirely natural vegetation types, as is the case in most European landscapes. However, agricultural management has created a range of cultural landscapes, varying with different geological and climatic influences and with diverse land use practices. By exercising its influence on the natural components of the landscape agriculture has also enriched aspects of Ireland's wildlife heritage over the millennia.

More recent developments in agriculture, as expressed in the processes of specialisation, concentration and intensification of agricultural production outlined in the previous chapter, have, at least in some areas, have had negative environmental implications. The visual fabric of Ireland's landscapes is changing, some habitats and species are hard pressed for survival and pollution from agricultural sources impacts upon wildlife, soil and water resources as well as on human health.

Obviously agriculture is only one of the factors which impact upon the rural environment. Other factors include urbanisation and suburbanisation, industrial development, transport structures, tourism developments, afforestation and peat extraction. However, as the main land use type in terms of area agriculture in Ireland remains the primary determinant of rural landscape change.

While pressures on the environment due to agricultural structural changes are more pronounced in a number of European regions, particularly in northern Germany, the Netherlands, parts of France or south-east England, a number of adverse environmental changes have occurred in Ireland in recent decades. These will be addressed in the following sections.

Baseline Information

Satisfactory data on land use change, habitat change or species trends are scarce. The first comprehensive large-scale land use inventory of Ireland has been compiled as part of the EC CORINE Land Cover Project which began in the late 1980s. There have been some local surveys, and the Wildlife Service of the Office of Public Works (OPW) carried out national or regional surveys of certain habitat types, including peatlands, woodlands and grasslands, as well as a number of species surveys. The first comprehensive survey, the National Heritage Inventory of the 1970s, resulted in the identification and the drawing up of a list of Areas of Scientific Interest in Ireland (An Foras Forbatha, 1981). This inventory was updated and revised in the 1980s (Wildlife Service, 1989). Further updating in the 1990s by the National Parks and Wildlife Service (NPWS) resulted in the publication of the list of proposed Natural Heritage Areas (pNHA). These pNHA sites have served as the baseline inventory for the listing of proposed Candidate Special Areas of Conservation (pCSAC) which is being prepared in order to meet Ireland's obligations under the EU Habitats Directive. Remote sensing and the use of Geographic Information Systems (GIS) are likely to improve the data situation in the future.

A limited amount of data on land use and landscape features is being collected by approved planners for farms participating in the Rural Environment Protection Scheme. This information is held by the Department of Agriculture and Food and may serve as reference material in the future.

With regard to species trends the amount of data available is also limited and consists of material produced by, amongst others, the Wildlife Service Research Branch, universities, NGOs such as BirdWatch Ireland, the British Trust for Ornithology and the Biological Records Centre, Monkswood in the UK. Red Data Books have been prepared for some groups of flora and fauna.

Water quality data are available from the Environmental Protection Agency (EPA). The latest published data relate to the four year survey period of 1991-1994. Data on fish-kills are collected by the Marine Institute on an annual basis.

4.1. Impacts on Ecological Processes and Life Support Systems

Ecological processes can be defined as ‘those processes that are governed, supported or strongly moderated by ecosystems and are essential for food production, health and other aspects of human survival and sustainable development’ (IUCN, 1980). Ecological processes govern energy flow and nutrient cycles in ecosystems.

Agricultural activities break both energy flow and nutrient cycles to a greater or lesser extent. For example, the harvesting and removal of crops leads to a loss of both nutrients and (fixed) energy from agricultural systems. In a mixed crop and livestock enterprise both energy and nutrients would to some extent be returned to the land in the form of animal manure and harvest residues. In specialised enterprises energy flow and nutrient cycles are disrupted to a greater extent. Intensive livestock units may be faced with the problem of the disposal of surplus nutrients in the form of slurry, while conventional crop production requires nutrient inputs in the form of purchased chemical fertiliser (see case studies 5.3, 5.4, 5.6). Fertiliser production may lead to further environmental problems as a consequence of the energy consumed and the waste generated in its production. If animal waste is transported from a ‘surplus region’, e.g. from large pig or poultry production units to another region where it could be used as fertiliser again energy inputs are required for transport.

The closer agricultural systems are modelled on the original ecosystems which are being modified, i.e. the more self-contained and complex they are, the more efficient (in terms of energy use and nutrient cycling) and sustainable they become and the less inputs are required.

4.2. Impacts on Biological Diversity

4.2.1. What is Biodiversity

The word `biodiversity' is a contraction of biological diversity and is commonly used to describe the number, variety and variability of living organisms. In order to manage biodiversity, it has to be measured, and measures of diversity only become possible when some quantitative value can be ascribed to them and when these values can be compared. It is thus necessary to try and disentangle some of the separate elements of which biodiversity is composed. It has become widespread practice to use 'Biological diversity' as an umbrella term for natural diversity at three hierarchically-related levels of biological organisation: (i) genetic diversity at the molecular level of biological systems, (ii) species diversity and (iii) ecosystem diversity, i.e. the number and frequency of ecosystems (Wilcox, 1983; McNeely, 1988).

Genetic diversity

Genetic diversity represents the heritable variation within and between populations of organisms. Genetic variation enables both natural evolutionary change and artificial selective breeding to occur.

Species diversity

Very commonly biodiversity is used as a synonym of species diversity, and of 'species richness' in particular. Species richness describes the number of species in a defined area or habitat. There are a number of difficulties involved in this approach as (i) the concept of what represents a distinct species differs considerably between groups of organisms, (ii) organisms of a defined species which differ widely from each other in some respect by definition contribute more to overall diversity than those which are very uniform, (iii) the more different a species is from any other species the greater its contribution to any overall measure of global biological diversity and (iv) the ecological importance of a species within an ecosystem can have a direct effect on community structure, and thus on overall biological diversity.

Ecosystem diversity

The quantitative assessment of diversity at the ecosystem, habitat or community level remains problematic as there is no unique definition and classification of ecosystems at the global level. It is thus difficult in practice to assess ecosystem diversity other than on a local or regional basis and then the assessment is based largely on their vegetation. Ecosystem diversity is often measured indirectly through measures of the diversity of the component species, using a variety of approaches. However, there is no one authoritative index for measuring ecosystem diversity. Additionally ecosystems are different from genes and species in that they explicitly include abiotic components, such as soils and climate. For this reason the impact of agriculture on soil and water resources will also be assessed in this chapter.

Biodiversity - its meaning and measurement

‘The differences between these conceptual perspectives on the meaning of biodiversity, and the associated semantic problems, are not trivial. Management intended to maintain one facet of biodiversity will not necessarily maintain another. For example, a timber extraction programme which is designed to conserve biodiversity in the sense of site species richness may well reduce biodiversity measured as genetic variation within the tree species harvested. Clearly, the maintenance of different facets of biodiversity will require different management strategies and resources, and will meet different human needs. Even if complete knowledge of particular areas could be assumed, and standard definitions of diversity be derived, the ranking of such areas in terms of their importance with respect to biological diversity remains problematic. Much depends on the scale that is being used. Thus, the question of what contribution a given area makes to global biological diversity is very different from the question of what contribution it makes to local, national or regional biological diversity. This is because, even using a relatively simplified measure, any given area contributes to biological diversity in at least two different ways - through its richness in numbers of species and through the endemism (or geographical uniqueness) of these species. The relative importance of these two factors will inevitably change at different geographical scales, and sites of high regional importance may have little significance at a global level. Neither of these factors include any explicit assessment of genetic diversity. Although the word biodiversity has already gained wide currency in the absence of a clear and unique meaning, greater precision will be required of its users in order that policy and programmes can be more efficiently defined in the future’ (WCMC, 1995).

4.2.2. Agriculture and Biological Diversity

Biodiversity changes in time and space. While the known changes over geological time are not relevant in the context of this study, agriculture's recent impacts on genetic, species and habitat diversity are at the core of its concern. Globally there is large-scale geographic variation in species diversity, the underlying reasons for which are not fully understood. Ireland's biological diversity has been strongly influenced by two factors. Firstly, after the last glaciation landbridges to Britain and the continent were severed before major recolonisation by some species groups could occur which left the island's flora and fauna considerably impoverished. Secondly agricultural land use has enriched aspects of the wildlife heritage over thousands of years due to large-scale ecosystem modification. For example the removal of a forest cover and its substitution with grassland or tillage gives light-demanding species larger areas in which they can survive and reproduce. Furthermore farmers have extended the range of a number of species by introducing species to areas that they probably would not have reached without human influence. The maintenance of existing levels of diversity would appear to involve the maintenance of those landscapes which are, at least in part, man-made along with adequately sized areas of natural ecosystems. It is commonly accepted that today a number of species and species communities in Ireland are dependent upon the continuation of certain specific agricultural practices for their survival.

 4.2.3. Genetic Diversity in Agriculture

Farming activities have contributed to genetic diversity of domesticated species through cultivation, selection and breeding over millennia. This genetic diversity is central to a number of applications in agriculture, i.e. livestock breeding, adjusted varieties, food and fibre production and medicinal plants. The loss of biodiversity in crop varieties and livestock breeds is of almost negligible significance in terms of overall global diversity, but genetic erosion in these populations is of particular human concern in so far as it has implications for food supply and the sustainability of locally-adapted agricultural practices. ‘For domesticated populations, the loss of wild relatives of crop or timber plants is of special concern for the same reasons. These genetic resources may not only underlie the productivity of local agricultural systems but also, when incorporated in breeding programmes, provide the foundation of traits (disease resistance, nutritional value, hardiness, etc.) of global importance in intensive systems and which will assume even greater importance in the context of future climate change. Erosion of diversity in crop gene pools is difficult to demonstrate quantitatively, but tends to be indirectly assessed in terms of the increasing proportion of world cropland planted to high yielding, but genetically uniform, varieties’ (WCMC, 1995). From an anthropocentric point of view the variety of genes found in nature thus represents a resource of enormous significance. At the same time ‘the genetic variability contained in wild species is essential for their very survival’ (Wilcox, 1982, see Vida, 1978).

4.2.4. Agricultural Impacts on Genetic Diversity

Genetic diversity, as represented by genetic differences between discrete populations within wild species, is liable to reduction as a result of the same factors that impact on species diversity, i.e. direct (hunting, collection and persecution) and indirect (habitat destruction and modification) factors (WCMC, 1995).

A Country Report on the needs and opportunities in the field of agricultural plant genetic resources has been submitted to the UN Food and Agriculture Organisation (Department of Agriculture and Food, 1995a). However, this report does not include an analysis of the status of current agricultural plant genetic resources.

Due to the lack of baseline data no quantitative assessment can be made of the loss of genetic variability in either wild or domestic species in Ireland. The intensification of agricultural production, desired economies of scale which demand high levels of uniformity, and market pressures would appear to have led to the abandonment of a number of Irish breeds, strains and landrace varieties. As a result these have died out or become rare; some to the point of near extinction with an inadequate gene pool remaining. Some cereal varieties are held in national and international ex-situ collections. Table 4.1. gives an overview of rare animal breeds, their overall status and their status under the REPS supplementary measure ‘Rearing animals of local breeds in danger of extinction’.

The REPS offers incentives to breeders of some of these breeds. To be eligible, a farmer must be a participant in REPS and must be a member of a relevant breed society or conservation organisation and must keep relevant records.

With regard to threatened domestic plant species there is very little information available. The Irish Genetic Resources Conservation Trust together with the Irish Seedsaver Association and the Trinity College Botanic Gardens are currently engaged in the in-situ and ex-situ conservation of traditional Irish cereal varieties. The Small Grains Collection (US) donated samples of wheat and oat landraces in 1996 which have been cultivated in Kilkenny. The collection will probably be enlarged by donations from the Russian Vavilov Institute in the near future and will bring the collection of heritage cereals to about forty varieties (Miklas, 1998). Small-scale traditional rotational tillage on the Aran Islands may have preserved a rye landrace. However, the genetic characteristics of this rye have not yet been determined (Waldren, pers. comm. 1997). The Irish Seed Saver Association in collaboration with University College Dublin are also involved in the re-discovery and preservation of old Irish apple varieties. Their collections in Dublin and Scariff, Co. Clare now contain 140 varieties, many of which had been considered extinct.

Information on other crop species could not be obtained.

 4.2.5. Agricultural Impacts on Species and Habitat Diversity

The loss of biological diversity can take many forms but at its most fundamental and irreversible it involves the extinction of species. While species extinction is - over geological time - a natural process which occurs without the intervention of man, it is beyond question that extinctions caused directly or indirectly by man are occurring at a rate which far exceeds any reasonable estimates of background extinction rates (WCMC, 1995).

In the context of this study it is primarily habitat destruction and modification and their indirect effects on species diversity which are of relevance. Virtually any form of sustained human activity results in some modification of the natural environment. This modification can affect the relative abundance of species. It can increase diversity but in extreme cases may also lead to species extinction. This may result from the habitat being made unsuitable for the species or through habitat fragmentation. Habitat fragmentation divides previously contiguous populations of species into small sub-populations. ‘If these are sufficiently small, then chance processes lead to raised probabilities of extinction within a relatively short time’ (WCMC, 1995). There is a general agreement amongst scientists that habitat protection is central to species protection (SRU, 1985; Plachter, 1991).

Endangered species and the Red Data Lists

The Red Data Lists or Red Data Books identify the status of species in terms of their risk of extermination within a given area, usually on a national basis. Such lists have been drawn up for various groups of fauna and flora, but rarely for habitat types. One of the criticisms of Red Data Lists is that they merely monitor the final phases of species decline, i.e. species have to become rare before they are considered threatened and therefore worthy of protective measures (Bauer, 1989). Furthermore it is usually only a fraction of the total fauna and flora that is assessed in a formal manner. Little is known about the status of most invertebrates and lower plants. In Ireland Red Data Books have been prepared for vascular plants (Curtis & McGough, 1988), Characeaea (Joint Nature Conservation Committee (JNCC), 1992) and vertebrates (Whilde, 1993).

Rarity can only be defined with reference to a particular area. In taking a European perspective it is worth noting that a number of species which are still relatively common in Ireland are rare, threatened or extinct on the Continent. This aspect has been taken into account in the drawing up of Irish Red Data Books.

The known status of Red Data List species in Ireland is summarised in Table 4.2.

Indet. = Indeterminate; nt. = species which are not now rare/or threatened (applies to vascular plants only);

Int.Imp. = Internationally important; % refers to percentage of total number ofspecies in the respective group, where known; n.a. = not applicable.

 Reasons for species decline - habitat destruction

The prevailing causes of the decline and loss of species are habitat change and habitat loss, while direct persecution, wilful destruction, trapping, collection and sale is of minor importance for most species.

Ireland still hosts important populations of mammals such as a number of bat species, otters, pine marten and badgers which have become rare or threatened on the continent and which are vulnerable to habitat changes which can be induced by changes in agricultural land use such as for example a loss in habitat diversity, the drainage of wetlands or the loss of nesting sites for bats.

With regard to birds it can generally be said that bird species of upland habitats, wetland habitats and granivore species in the western regions have been negatively affected by changes in land use in recent decades. Table 4.3 shows that twenty-nine Red Data Book bird species, representing nearly 70 % of the total list are in some way dependent on agricultural land use for the maintenance of their habitats. The degree of dependence on certain agricultural land uses varies between species. The corncrake (Crex crex), for example, breeds almost exclusively on agricultural land in Ireland, i.e. in meadows cut for hay or silage (see Case Study 5.7). The black-tailed godwit (Limosa limosa) nests on lowland wet pasture and its breeding success is directly linked to very low livestock densities (see Beintema et al., 1982).

A number of Ireland's wintering birds such as greenland white-fronted geese (Anser albifrons flavirostris), whooper swans (Cygnus cygnus) or barnacle geese (Branta leucopsis) use agricultural grassland for winter feeding. The chough (Pyrrhocorax pyrrhocorax) is dependent on grazed coastal swards usually alongside cliffs. Other species such as quail (Coturnix coturnix) and grey partridge (Perdix perdix) make use of both grassland and crops but also need hedgerows and patches of unutilised vegetation for cover and breeding. Important habitats for many of Ireland's upland bird species have been severely damaged as a direct result of excessive sheep stocking densities. The bird species affected most were red grouse (Lagopus lagopus), dunlin (Calidris alpina), golden plover (Pluvialis apricaria) and hen harrier (Circus cyaneus) (Murphy, 1995).

Sources: Whilde (1993), RSPB (1991), Peterson (1983), Nairn et al. (1988)

Species listed in the Red Data Book for vascular plants are grouped together on a phytosociological basis in Figure 4.1. There are obvious concentrations of extinct, rare or threatened species in phytosociological units (classes) which represent agricultural habitats. These concentrations occur in the phytosociological class Secalinetea (arable weeds which are associated with cereals) and in the phytosociological class Chenopodietea (arable weeds which are associated with root crops) and generally in anthropo-zoogenic grasslands and heaths. A further large group of Red Data List species occurs in the ‘wall-fern class’ (Asplenietea) which includes open vegetation of rock crevices, such as limestone pavements and walls. Within the anthropogenic meadow and pasture communities most Red Data List species can be assigned to wet marginal grasslands (Molinietalia communities) as opposed to the drier grasslands of the Arrhenatheretalia type, which are usually more intensively managed (Figure 4.1, Appendix III). Other important grassland types, which host concentrations of Red Data Book plants, are sandy dry grasslands, mostly coastal dune grasslands (Koelerio-Corynephoretea), and the dry limestone grasslands (Festuco-Brometea) found principally in the Burren of Co. Clare (see Case Study 5.1) as well as on calcareous eskers and moraines in the Irish midlands.

Source: based on Curtis & McGough (1988). An explanation of the abbreviations for the phytosociological units is given in Appendix III.

A number of factors which contribute to the decline of Irish Red Data Book plant species have been identified by Temple Lang & Hickie (1992) and these are listed in Table 4.4. However, the direct contribution of agriculture to species decline as opposed to that caused by other land uses has not been quantified for Ireland. Such an analysis has been carried out by Sukopp (1981) for Germany in which he concluded that 38% of plant species losses could be attributed to agricultural land use. While the environmental problems faced in Ireland and Germany are not of the same order of magnitude, similar trends can reasonably be expected for Ireland.

Source: Temple Lang & Hickie (1992)

Agricultural activities leading to habitat destruction

A number of factors which are directly or indirectly linked to agriculture have led to habitat loss and habitat change in Ireland. These include:

• Arterial and field drainage
• Commonage division
• Land reclamation including the removal of small scale farmland habitats such as trees, hedges, dry-stone walls, remnant woodlands and scrub
• The substitution of silage-making for hay-making
• The abandonment of small-scale rotational cropping
• Increasing sheep numbers and overgrazing of marginal grasslands and heaths
• Increasing use of fertilisers, increasing stocking densities and increased nutrient inputs through supplementary feeding
• Increasing use of pesticides

The origins of some of these factors, particularly drainage practices, can be traced back to the last century (Ryan, 1986), but most changes would appear to be associated with the entry of Ireland into the EU and the various farm support schemes and special aid schemes that have been subsequently available (see Chapter 1).

Arterial drainage

From the middle of the last century until the passing of the 1945 Arterial Drainage Act, 203,600 ha land had been drained. Under the 1945 Act thirteen major catchments and at least 25 small catchments have been drained (Figure 4.2.) affecting 262,800 ha of land (Burdon, 1986). The last schemes were carried out into the mid 1980s in the Boyne, Maigue, Corrib-Mask and Boyle-Bonet catchments.

State investment in drainage construction works has fallen considerably since the mid-eighties (Temple-Lang & Hickie, 1992) and it seems unlikely that schemes such as the Finn-Lackey or the Shannon will go ahead.

Field drainage

Arterial drainage has paved the way for field drainage schemes. National grant aid for field drainage was given under the Land Project 1949, which led to the drainage of 1,168,000 ha Within the framework of the CAP further schemes were enacted which grant-aided field drainage. Work was carried out under the Farm Modernisation Scheme 1974-1985 (202,350 ha) (Burdon, 1986) and the Western Drainage Package 1979-1988 (182,540 ha) (Minister for Agriculture and Food, 1989). The suspended Farm Improvement Programme of 1986 only provided for minor drainage works in conjunction with field reclamation and no figures are available for the extent of works of this nature. As with arterial drainage, the extent of grant-aided field drainage has declined substantially through the 1980s. No data are available as to the extent of non-grant aided works.

The total area drained under the various Acts and schemes is 2,022,590 ha27 or almost thirty per cent of the total area of Ireland. (Burdon, 1986). Temple Lang & Hickie (1992) listed a number of sites which had been designated as Areas of Scientific Interest and which had been damaged or destroyed since their designation. State and EC funded arterial drainage schemes were responsible for much of the damage. Drainage has also resulted in damage to fisheries (Baldock, 1990).

One particular rare form of wetland, the turlough was particularly affected by arterial drainage schemes, primarily during the last century (Coxon & Drew, 1986). For example, the Rahasane turlough in eastern County Galway, which forms part of the Dunkellin river catchment, was drained as recently as 1992. This turlough is a wetland of international importance for wintering wildfowl. It had been designated an Area of Scientific Interest of international importance by the Wildlife Service and was recognised as meriting the status of a Special Protection Area (SPA) under the EU Wild Birds Directive. Nevertheless the drainage operation could proceed, as no grant aid was provided, which in turn ruled out any consultation between representatives of the Department of Agriculture and Food and the National Parks and Wildlife Service of the OPW on the matter. The site is now a proposed Candidate Special Area of Conservation.

The drainage and improvement of wet meadows has been implicated in the decline of the marsh fritillary (Euphydryas aurinia), now one of the most rapidly declining butterflies species in Europe (Thomas & Lewington, 1991). The species is listed in Annex IIa of the Habitats Directive as a priority species of community interest the conservation of which requires the designation of Special Areas of Conservation (EC, 1992).

Commonage division

Commonage division has been carried out by the Land Commission in the western areas, affecting 23,412 ha in 248 commonages between 1982 and 1989. Nearly half of the land subject to division was situated in County Mayo (Temple-Lang & Hickie, 1992; Minister for Agriculture and Food, 1991). Commonage division often provides the individual farmer with the incentive to manage the divided areas more intensively, i.e. by way of higher stocking rates or fertiliser inputs. Mountain and hill pasture improvement in Less Favoured Areas was eligible for grant-aid under the Farm Modernisation Scheme (1974-1985), the Farm Improvement Programme (since 1986) and the Programme for Western Development (1981-1990). The conditions governing the approval of farm improvement and development plans under these programmes would appear to have favoured individual as to group applications. This was demonstrated by the relatively small number of group applications sought for commonage improvement under the Programme for Western Development. According to Temple Lang & Hickie (1992) a number of sand dune and machair29 sites has been affected by commonage division. Habitat damage can be caused by the improvement of heather-moorland through drainage, fencing, fertilising and possibly reseeding, all of which are designed to increase the carrying capacity of these areas. This may in turn lead to overstocking on the remaining undamaged areas of rough grazing on holdings or commonages (NCC, 1990). Certain breeding waders of open moorland (e.g. golden plovers) shun enclosed areas (Ratcliff, 1976).

Land reclamation

Depending on the individual circumstances, land reclamation can involve the removal of scrub, trees, hedgerows and other small-scale farmland habitats, boulders and unnecessary fencing, and may also involve minor drainage operations. Within the framework of farm improvement plans, land reclamation was grant-aided under the now suspended Farm Improvement Programme with capital grants providing 30% and 20% of the capital costs in LFAs and other areas respectively. Aid had also been made available for lowland reclamation in the disadvantaged areas under the Programme for Western Development. Between 1981 and the end of 1990 more than 25,000 approvals for intensive lowland reclamation had been issued and payments of almost £20 million had been made. No figures for the extent of the areas affected are available.

The number of approvals issued for farm development plans peaked in the mid-eighties and declined subsequently. The rate of hedgerow loss and possibly that of other small-scale habitats has probably also declined. It was estimated by Webb (1988) that approximately 16% of all hedges have disappeared since 1938. Hedgerow removal appeared to be localised and concentrated on the larger farms irrespective of the farm type. The greatest losses were noted in the south County Laois and south County Kildare area, i.e. intensive tillage areas. Under the REPS hedgerows have to be maintained as part of the agri-environmental plan for each farm.

Speculation that on some farms hedgerows as well as other small-scale habitats were removed before entry into REPS in order to avoid the maintenance work required under the scheme was re-enforced by the issue of a circular from the Department of Agriculture and Food to REPS planners stating that they had received a complaint from the NPWS to this effect and that such practices were unacceptable (Department of Agriculture and Food, 1995b).

Land reclamation has been intensively studied in the Burren region of Counties Clare and Galway. Two separate surveys found that more than 1,600 hectares of land had been reclaimed in the 1980s and early 1990s and this has impacted on habitats of international importance such as limestone pavements and orchid-rich limestone grasslands in former Areas of Scientific Interest (ASIs), proposed NHAs and proposed CSACs. Details on the reclamation studies and the intensification of agricultural management in the Burren are outlined in Case Study 5.2. In the early 1990s almost three kilometres of hedgerows and dry-stone walls had also been removed in the process of reclamation (Drew, 1996). Under the European Communities (Natural Habitats) Regulations, 199730 reclamation in the Burren has become a 'notifiable action' in the pCSACs and requires the consent of the responsible Minister.

Land reclamation and re-seeding have also been implicated in the decline of the chough (Whilde, 1991).

Substitution of silage for hay

The increasing substitution of silage for hay has already been noted in Chapter 3.1.8. Since 1970 there has been a steady increase in silage production, accelerated by a series of wet summers in the mid-eighties. The production of silage has increased from 0.3 million tonnes in 1960 to over 20 million tonnes in 1990 (Government of Ireland, 1997). Silage making is generally associated with more intensive management than hay production. The intensity of management varies. The number of cuts per year can vary between one and four, with fertiliser or slurry being applied between cuts and there may be frequent reseeding with monodominant high yielding grasses such as rye grass (Lolium perenne) (see Mayes & Stowe, 1988). The switch from hay to silage production has been facilitated by investment aid for the installation or upgrading of fodder storage facilities provided under the Programme for Western Development (1981-1990), under the Farm Improvement Programme (since 1986) and the currently suspended Control of Farmyard Pollution Scheme (since 1989).

In recent years the decline of the internationally threatened corncrake (Crex crex) has been linked to the increase in grass silage production. Further reasons for the decline of this species include the conversion of hay meadows to closely grazed sheep pasture, encouraged by the introduction of the Ewe Premium in 1980 (Mayes & Stowe, 1988) and possibly the early grazing of grassland, which is subsequently closed off for silage production (Duff, pers. comm. 1992). This would reduce habitat availability during the early nesting season. Details on the Irish Corncrake Conservation Scheme and the role of the REPS in the conservation of the corncrake population are given in Case Study 5.7.

Abandonment of Small-Scale Rotational Cropping

The traditional agricultural practice of small-scale rotational cropping, the maintenance of a local seed supply with no or only occasional crop cleaning and the lack of herbicide use have ensured the survival of a number of rare or threatened arable weed species, which were discovered by National Parks and Wildlife Service botanists in 1987 (Curtis et al., 1988). Two of these species, darnel (Lolium temulentum) and cornflower (Centaurea cyanus), had previously been considered extinct in Ireland and the other two species, the bristle oat (Avena strigosa) and smooth brome (Bromus racemosus) have become very rare. All these species apart from the bristle oat are listed in the Irish Red Data Book.

No particular agricultural support scheme can be held responsible for the abandonment of small-scale rotational cropping. This development is part of the general trend towards intensification and specialisation.

Overgrazing

The problem of overgrazing by sheep in the upland regions in the west of Ireland was first highlighted by the Salmon Research Agency in 1990 when it reported damage to important game fisheries in the west, due to run-off of excessive quantities of peat silt from eroding peatlands. Bleasdale & Sheehy Skeffington (1992) found that there was little remaining heather moorland in Connemara and concluded that this was due, at least in part, to the high grazing pressure in the region. While overgrazing can negatively affect a number of vegetation types attention is currently primarily focused on the damage done to blanket bog and wet heath communities.

On heathlands overgrazing reduces the cover of heather and leads to increases in grass species such as purple moorgrass (Molinia caerulea) and mat grass (Nardus stricta). Severe cases of overgrazing lead to soil erosion, particularly in the winter months. In the late 1980s this was still a localised phenomenon. By the mid-1990s the situation had become so serious that it had reached the attention of the popular media. In recent years a number of studies have been carried out which have assessed the extent of the damage and its impacts (see case study 5.1.). The high stocking rates are a direct outcome of the sheepmeat regime of the EU and the headage payments in the LFAs. Following the 270% growth of the national flock (June enumeration) between 1980, i.e. the year of the introduction of the Ewe Premium, and 1992, there has been a decline from 1992 onwards, which appears to be attributable to market forces. The uptake of the supplementary measure 'Degraded Commonages' under the REPS was very limited up to 1997 and therefore does not seem to have been a factor in the decline of the national flock in recent years. The problem of overgrazing and its causes are discussed in more detail in case study 5.1.

Increased nutrient inputs

The excessive use of fertilisers, particularly nitrogen and phosphorous, has a number of indirect effects on habitats. Nutrient enrichment of agricultural as well as non-agricultural habitats (the latter being caused by run-off, leaching or drift) impacts on the competitiveness of species that are adapted to nutrient-poor conditions such as those which are prevalent in heathland, calcareous grassland or oligotrophic waterbodies. An example of this type of impact has been demonstrated by a study of the effects of fertiliser application on the Burren limestone grasslands (An Foras Forbatha, 1972). It was shown that fertilisation resulted in an increased yield and percentage cover of most grasses, white clover (Trifolium pratense), compositea and ‘agricultural weeds’, while the ‘non-weed species’ that were abundant in the limestone sward, were reduced in yield, variety and percentage cover. The latter group includes a number of rare and threatened species for which the Burren is renowned. Calcareous dry grasslands are severely threatened habitats in Europe. Fertilisation is one of the main factors in their decline (Council of Europe, 1981).

The eutrophication of waterbodies, e.g. through phosphate run-off and leaching, can lead to excessive growths of algae and other water plants31and may cause deterioration of water quality to the point of the ‘collapse’ of the ecosystem through oxygen depletion. However, some habitat types have such a low nutrient status that even very minor eutrophication can disrupt or eliminate plant and animal communities. This would be true for many western oligotrophic lakes and has been demonstrated, for example, by the collapse of the arctic charr populations in Lough Conn and Lough Corrib in the early 1990s (EPA, 1996). The problem of eutrophication will be further discussed in the following section on water quality.

It has been shown in the discussion of the intensification of Irish agriculture in Chapter 3.1.8 that there has also been a dramatic increase in the production and consumption of compound feeds which - together with the increase in overall livestock numbers and increased fertiliser inputs - is likely to have lead to a major increase in nutrient inputs per unit area with repercussions for biodiversity as outlined above.

Increased pesticide use

Data on pesticide use in Ireland have been given in Chapter 3.1.8. The extinction of some arable weed species is linked, at least in part, to herbicide use in tillage production. An indirect effect of a changing vegetation structure and composition following herbicide applications is the loss of invertebrates, such as carabid beetles or lepidoptera (butterflies and moths) which are often dependent on the presence of particular plant species. The maintenance of conservation headlands in tillage crops, i.e. marginal strips which do not receive fertiliser or pesticides, has been shown to have a positive effect on both floristic and faunal diversity (Raskin et al., 1992). Furthermore, organic production techniques, which do not permit pesticide usage, have been shown to be particularly beneficial to the preservation of rare arable weeds and to the maintenance of general plant species diversity (Frieben, 1992) as well as to increased species numbers of birds, lepidoptera and arthropods. A compilation of recent comparative research in Europe on biodiversity on organic and conventional farms is included in Appendix IV. Following the introduction of the REPS there has been a very significant growth in the number of certified organic farms in Ireland which might be expected to have a positive impact on biodiversity. Evaluation reports on the implementation of the EU agri-environmental measures in other Member States have highlighted the proven environmental benefits of organic farming on soil and water quality and on biodiversity (CEC, 1997).

Despite the massive growth of the national sheep flock since 1980 there does not appear to have been a corresponding increase in the use of insecticides, according to available figures (see Chapter 3.1.8). Sheep are dipped to control a range of ectoparasites, including scab and blowfly. Apart from having serious human health implications sheep dips are toxic to aquatic life. Recent statistics indicate that the majority of sheep dip pollution in Scotland is now caused by pyrethroid dips which are replacing the more traditional organophosphate ones. While the pyrethroid dips are thought to be less harmful to human health than the organophosphate based preparations, they are 100 times more toxic to aquatic life (Scottish Environmental Press Agency (SEPA), 1997). Information on the relative amounts of the different types of dips used in Ireland and on potential damage to aquatic life from non-point source pollution by sheep-dip could not be obtained for this study.

The protection of semi-natural habitats in Special Areas of Conservation

Under the EU Habitats Directive of 1992 Ireland is under an obligation to designate and maintain or restore, at a favourable conservation status, natural and semi-natural habitats and species of wild fauna and flora of Community interest as defined in the Annexes of the Directive. The designated sites will contribute to the NATURA 2000 ecological network across the EU. Where it is deemed necessary the state can further encourage the management of linear features in the landscape which are essential for the migration, dispersal and genetic exchange of wild species, such as rivers with their banks or traditional field enclosures (EC, 1992).

In March 1997 the Minister for Arts, Heritage, Gaeltacht and the Islands notified the transposition into Irish law of the EU Habitats Directive and the designation of proposed Special Areas of Conservation. ‘The areas involve over about 550,000 hectares in some 400 sites. Many of these valuable sites are contained in the western part of the country. The most extensive areas involve blanket bog, heath and uplands, covering about 200,000 hectares; lakes and rivers, approximately 100,000 hectares; estuaries, mudflats and cliffs, about 90,000 hectares; a further 40,000 hectares of shallow bays and 54,000 hectares of saltmarsh, machair and sand dunes. Other habitats include 30,000 hectares of limestone pavement, 10,000 hectares of raised bogs, 15,000 hectares of fens and 3,000 hectares of turloughs.’ (Higgins, 1997). Ireland hosts sixteen priority habitat types and a further 42 non priority habitat types of Community importance under the terms of the Habitats Directive. Out of a total of 400 sites to be designated, 214 host priority habitat types (NPWS, 1995). According to the Deputy President of the Irish Farmers’ Association (IFA), Mr Michael Slattery about 500,000 ha, i.e. 90% of the candidate SAC lands are owned by ‘up to 10,000 farmers.

The maintenance of the favourable conservation status of many of the habitats covered by the Habitats Directive and included in the SACs is directly (through active management, e.g. grazing) or indirectly (through the absence of negative impacts, e.g. nutrient inputs) dependent on sustainable agricultural practices. Farmers who have some or all of their lands in SACs are being supplied with a map of the area being proposed for designation, a description of the site indicating the for its designation, a list of notifiable actions, and information on procedures for objections and appeals as well as on compensation. A compensation package has recently been agreed with the European Commission. Agreed sets of management prescriptions are still outstanding for a number of the habitat types.

4.3. Impacts on Ground and Surface Water

Agricultural impacts on water resources in Ireland include point source pollution from farmyard run-off, silage run-off, slurry tanks and pesticide spills, as well as wider problems resulting from nitrate and phosphate leaching and run-off. 

4.3.1. Impacts on Ground Water

Ireland's groundwater quality and pollution risks to groundwater have been reviewed by Daly (1992). Since there is no nation-wide or systematic groundwater quality monitoring in Ireland, there is a paucity of information on groundwater quality. Only drinking water sources are monitored on a regular basis by the local authorities. The existing information suggests that the main problems arise from point source pollution (e.g. farmyards, septic tanks, accidental spillage) rather than from diffuse sources. However, in the more intensively managed agricultural areas background nitrate levels have risen.

An investigation of groundwater nitrate concentrations in the south and north-east of the country in the early 1990s showed that 97 per cent of samples had nitrate concentrations which were less than the maximum admissible concentration (MAC) set by the Drinking Water Regulations. The information gained in the study suggests that nitrate contamination occurs in individual boreholes and wells, probably due to the proximity of waste sources such as silage and slurry pits, but that the general bodies of groundwater are relatively free of this contamination (EPA, 1997).

A study carried out by Thorn & Coxon (1992) attempted to relate land use and soil management characteristics to the quality and chemistry of borehole waters in Counties Kildare and Carlow. The results suggest that fertiliser use and the proportion of arable land in the vicinity of the boreholes impacts upon groundwater quality. However, difficulties in the interpretation of the study results arise as a consequence of the rotation of arable land and grassland and as a consequence of point source pollution arising from poor agricultural waste management and improper siting of wells.

Studies in a number of karst areas in Ireland have shown that in most places surveyed more than fifty percent of wells and springs were contaminated - usually by septic tank effluent or wastes from farming activities - with the most intense pollution occurring following rainfall (Thorn, 1991).

Water quality problems in the Burren region have been studied by Drew (1990). The characteristics of the karst aquifer make the groundwater resources in the region particularly vulnerable to contamination. Silage effluent and septic tank overflow bacterial contamination were identified as the most widespread form of pollution. Increasing use of artificial fertilisers was indicated by Drew (1990) as being a possible source of increased nitrate levels in a spring draining part of a hill in the central Burren.

Further details on water quality problems in the Burren region are included in Case Study 5.2.

While in areas such as the Burren with its thin and patchy soils pollutants very quickly reach the karst aquifer, in other regions with thicker soils and a different underlying geology the time taken for pollutants to reach groundwater may vary and can take up to 20-30 years (CEC, 1996). Thus the full impact of the increase in nitrogenous fertiliser use (see Chapter 3.1.8), particularly in the more intensively managed regions, may take some time to emerge.

4.3.2. Impact on Surface Water

Overall the surface water quality in Ireland is good, particularly if compared to many continental European countries. In the 1991-1994 EPA survey period the bulk (71 per cent) of river and stream channels surveyed were in an unpolluted35 condition. However, since long-term water quality monitoring of rivers began by An Foras Forbatha in 1971, overall water quality has deteriorated. The following overview is based on the report on ‘Water Quality in Ireland 1991-1994’ by the Environmental Protection Agency (EPA, 1996).

The analyses of long-term (since 1971) and recent (since 1987) trends up to and including the survey period 1991-1994 for rivers and streams shows that there has been:

• A reduction in unpolluted channel length from 84 percent to 57 percent of the total surveyed since 1971
• A five-fold increase in the extent of slight pollution since 1971
• A three-fold increase in the extent of moderate pollution since 1987
• A reduction from 6 percent to approximately 1 percent in the extent of serious pollution since 1971(EPA, 1996)

The gradual decrease of channel length affected by serious pollution is largely attributed by the EPA to the installation or improvement of sewage treatment facilities while the upward trend in eutrophication is largely attributed to diffuse agricultural sources, i.e. organic and inorganic fertilisers, and to a lesser degree to point source sewage and industrial discharges.

The suspected causes of all observed pollution in the channels surveyed is given in Figure 4.4. The category 'Agriculture' includes the adverse effects of overgrazing by sheep in the western regions (such as scouring, siltation and substratum instability with the ensuing loss of biodiversity and damage to salmonid productivity), as well as the eutrophication caused by diffuse and point sources of agricultural waste.

The EPA report attributes almost half of the observed slight and moderate pollution and a quarter of the observed serious pollution of rivers and streams to agriculture with the great bulk of serious pollution being chronic as opposed to 'once-off' pollution incidents. 'Once-off' type pollution events, as for example those caused by waste spillages or releases of short duration, are unlikely to be accurately reflected in the EPA data due to the nature of the survey (EPA, 1996).

Eutrophication

The on-going eutrophication is now the main problem affecting inland waters. Therefore the key physico-chemical parameters of interest are nitrates and phosphates, particularly the latter, which is considered to be the limiting nutrient in freshwaters. Most of the nitrate and phosphate found in natural waters comes from external organic and inorganic sources, principally sewage and industrial waste discharges, and from the run-off from agricultural land of artificial fertiliser and slurry (EPA, 1997).

Diffuse agricultural sources of phosphorus (P) are a major cause of eutrophication in Ireland's surface waters and rainfall-induced run-off from intensive agricultural lands is considered to be responsible for a very large proportion of phosphorus inputs into certain lakes in Ireland (EPA, 1997). Of particular concern is the land-spreading of volumes of pig and poultry slurry from intensive animal rearing facilities which exceed the assimilative capacity of the land available for their disposal (see Case Study 5.3).

Tunney (1990) estimated the P balance for the whole country for 1988 and found that there was an annual surplus of 46,000 tonnes, equal to 60% of total P inputs and that significant reductions in P applications could be made without reducing production. A recent joint Irish-UK study (Poulton et al., 1995) noted that current recommended phosphorus application rates in Ireland are two to three times higher than those issued by the Ministry of Agriculture, Food and Fisheries in the UK.

The built-up of soil P levels has been demonstrated by Carton et al. (1996). Between 1950 and 1991 the average P level of soil samples analysed at the Teagasc soil laboratory has increased more than ten-fold to 9.3mg/l. Since 1991 the level has dropped to about 8mg/l and stabilised. The authors also showed that soil samples received from farms which were about to enter the REPS had significantly lower P levels than non-REPS farms. This would suggest that on average the farms with excess soil P levels are not entering REPS at the same rate as those with low and medium soil P levels. Carton et al. (1996) conclude that farmers with high soil P levels (i) probably ignore the P contribution of slurry applications and (ii) probably do not follow Teagasc P recommendations. A Teagasc campaign was launched in the autumn of 1997 in response to a government target of reducing phosphate inputs to soil by 10% per year for five years, with a view to halving application rates. Teagasc recommendations for grazing and silage have recently been revised (see also Chapter 5.3.11).

Excessive levels of nitrate in rivers are usually associated with the higher applications of artificial fertilisers on arable land and the relative ease with which nitrate is leached from arable land. The EPA water quality survey figures clearly highlight the contrast between the relatively unimpacted rivers of the west and those in the east and south-east of the country where a higher proportion of land is used for tillage. While the bulk of the surface waters surveyed in the 1991-1994 period had nitrate concentrations below the EU guideline value, this value was exceeded in some rivers during the winter months for short periods and the highest concentrations were measured in south-eastern rivers. Nitrate concentrations in surface waters continue to increase in many rural areas and the rate of increase is greatest in the south-east region (EPA, 1996).

Overgrazing

Serious water quality problems result from overgrazing by sheep in the western regions. The EPA report categorised the observed effects on rivers as follows:

Fish kills

Fish kills are a symptom of extreme environmental disruption caused by a variety of factors including 'once-off' incidences such as spillages as well as diffuse pollution exacerbated by climatic factors. The number of fishkills by principal cause categories from 1986 to 1997 is shown in Figure 4.5. There has been a marked overall decline in fish-kills since the 1980s which is indicative of the considerable efforts by central and local government and by the Central and Regional Fisheries Boards in tackling the problem. The introduction of the Control of Farmyard Pollution Scheme in 1989 would appear to have been a significant factor in reducing agriculture-related fish kills. The number of fish-kills due to silage effluent has also decreased considerably in the past decade - apart from a peak of nine incidences in 1996 - which is probably attributable to the widespread change from the use of silage clamps to baled silage. However, agricultural sources remain the single biggest cause of documented fish kills in Ireland with thirteen incidences or one third of the total, followed by eleven incidences caused by eutrophication which may also partly attributable to diffuse agricultural pollution sources (Marine Institute, 1997a-c). The relatively high number of unexplained fish kills and those attributed to deoxygenation and eutrophication of unknown cause may reflect the considerable proportion of river stream channel which is subject to slight and moderate pollution (EPA, 1996).

Quantitative data on the presence of pesticides and other trace organics in water resources are very limited. Improper storage, handling, use and disposal of pesticides can result in pollution.

In 1996, the EPA published the results of a country-wide preliminary survey (December 1995 to December 1996) of pesticide residues in water supplies. Samples were taken in 26 counties from water supplies serving 1.8 million consumers. From 3,300 analytical samples only 5 samples contained levels of pesticides which were above the statutory drinking water quality standards. ‘On re-testing, the supplies with positive results were shown to be clear’ (Government of Ireland, 1997).

In the period 1994 to 1997 six fish kills were attributed to pesticides with the causes given as 'crop spraying', 'fungicide', 'herbicide', 'pesticide', 'sheep dip' and 'agri-chemical' (Moriarty, 1996; Marine Institute 1997a,b).

The recommended method of disposal for sheep dip residues is land spreading either mixed with water or mixed with farm wastes such as slurry. The releasing of these moderately persistent and highly toxic organo-phosphate (OP) dips or the new synthetic pyrethroid (SP) dips into watercourses, soakways or drains would be an offence under the Water Pollution Acts. Land spreading of diluted pesticides renders them subject to run-off risks similar to those of fertilisers. The fact that almost 60% of the national sheep flock is kept in the western regions36 where a large percentage of soils are categorised as being high in run-off risk (Sherwood 1992) gives rise to concern. Furthermore the risk of leaching in areas with thin soils and poor aquifer protection must be considered. Land spreading of diluted sheep-dip is permitted on lands under the REPS, subject to defined landspreading precautions and maximum volumes. In SACs the ‘use of any pesticide or herbicide’ is a notifiable action, but the disposal of diluted sheep-dip is not explicitly prohibited.

4.4. Impacts on Soils

Agricultural effects on soils include physical impacts such as soil erosion and soil compaction, and impacts on soil chemistry induced by the use of organic and inorganic fertilisers and biocides. A detailed analysis of the impacts on biological, physical and chemical properties of soils has been given elsewhere (SRU, 1985).

4.4.1. Soil Erosion

Soil erosion as a consequence of overgrazing has already been discussed in relation to peatlands, dunes and machair grasslands. A further problem has been identified by Gardiner & Burke (1983), namely the erosion of cultivated steeply sloping land in conjunction with heavy rainfall. These latter effects appear not to have been quantified to date. However, due to the small percentage of agricultural land under tillage and the very limited area of cultivated sandy soils susceptible to wind or gully erosion these impacts would appear to be very limited in extent (see Morgan and Rickson, 1988).

4.4.2. Micropollutants

Land spreading of organic waste can have undesirable effects on soil chemistry. Copper, used as a growth promoter in pig production, can accumulate in soils on which slurry generated in intensive pig production is spread. If applied to grassland, this can render the vegetation unsuitable for sheep grazing as sheep are sensitive to copper. Morgan & O'Toole (1992) have estimated that there has been a 32% increase in the volume of slurry generated from housed pigs between 1975 and 1990. The pigmeat sector was not targeted by the 1992 CAP reform and further expansion has taken place in recent years (see Chapter 3.1.7).

The use of phosphate fertilisers can also lead to accumulations of heavy metals in soils. Inorganic phosphate fertiliser contains cadmium (Cd), zinc (Zn), mercury (Hg) and other heavy metals as impurities. The considerable overuse of phosphorous fertilisers in Ireland has already been discussed and this may pose a risk of trace metal enrichment of soils. The application of sewage sludge to agricultural land must be viewed with even greater caution due to its high content of heavy metals (see O'Riordan & Dodd, 1992) and dangerous organic compounds (Lee, 1995). Long-term spreading of metal-rich sludges leads to topsoil heavy metal enrichment, particularly on grassland. It must be borne in mind that this process is irreversible. Excessive heavy metal intake is detrimental to both animal and human health.

Research conducted by Teagasc (McGrath, 1994) has shown that measurements of concentrations of organochlorines, pesticide residues and PCBs in Irish soils were indicative of low pollutant levels, reflecting a relatively low level of pesticide usage by EU standards. It was noted, however, that DDT and its breakdown products were still present at significant levels, especially in soils in fruit growing enterprises. Levels of heavy metals in soils were also indicative of low pollutant levels (Lee, 1995).

4.5. Impacts on Air Quality and Global Climate

Intensive livestock production gives rise to increased emissions of nitrous oxide (N20), ammonia (NH3) and - especially in the case of ruminants - methane (CH4). Land application and storage of slurry and manures are other important sources of ammonia emissions. Ammonia contributes to the acidification of soils and water through acid rain and methane and nitrous oxide are greenhouse gases. Nitrous oxide has been implicated as contributing to ozone depletion. Measured on the basis of their global warming potential CH4 and N20 emissions contributed 46% of Ireland's total emissions of primary greenhouse gases in 1990. CH4 and N20 emissions were 811,000 t and 29,400 t respectively with approximately 80% of emissions each resulting from agriculture. N20 emissions primarily arise from soils as a natural process of nitrogen circulating in the environment, but the use of nitrogen fertilisers, slurries and manures enhances this effect. Methane originates predominantly from enteric fermentation by ruminants - other sources are slurry and manures. While there has been a minor upward trend for methane in provisional data for 1995, nitrous oxide emissions decreased to approximately 26,000 t with 73% coming from agricultural sources. Stabilising animal populations and improved feed quality is expected to contribute to the stabilisation of direct livestock CH4 emissions (Government of Ireland, 1997; Department of the Environment, 1997).

Gaseous emissions of ammonia amounted to 123,000 t in 1994 and resulted almost entirely from agriculture. Thus, ammonia emissions from livestock were equivalent to almost 30% of fertiliser N usage in that year. The landspreading of fertiliser N can also result in nitrous oxide emissions and it is estimated that ‘an annual average of 5% of applied fertiliser N is emitted as N20’ (Lee, 1995).

The overall contribution of agriculture to CO2 emissions is very low (European Commission, 1997). However, grassland, and ‘especially low input grassland, is believed to act as a sink for carbon dioxide and nitrous oxide. Conversely ploughing of grassland releases large amounts of carbon dioxide through the decay of organic matter, for up to fifty years’ (Lee, 1995).

Peatlands, with which Ireland is well endowed, are an effective carbon sink. The average residence time for carbon in peat is approximately 10 times longer than in vegetation (Hickie, 1990). Drainage and cultivation of peatlands, be it for agricultural purposes or for afforestation, releases large amounts of carbon dioxide into the atmosphere and destroys their capacity to act as carbon sinks in the future. Thus peatland reclamation for agricultural purposes also contributes to the greenhouse effect.

Odour nuisances arise temporarily in association with the spreading of slurry or more permanently in connection with large animal production units, particularly in the pig and poultry sector.

A note on climate policy

The Kyoto Protocol under the United Nations Framework Convention on Climate Change, adopted on 11 December 1997 sets, inter alia, a legally binding target for the member states of the EU to reduce emissions of a basket of six greenhouse gases including carbon dioxide, methane, nitrous oxide, by 8 per cent below 1990 levels in the period 2008-2012. The protocol does not set separate targets for each gas and it is a matter for each party to achieve its target by the emission limitations and reductions considered most appropriate overall. In March 1998 the Department of the Environment received the results of a major consultancy study which identifies and evaluates the scope for intensifying existing policies and measures to limit and/or reduce greenhouse gas emissions and to make recommendations for the ongoing development of Ireland's greenhouse gas emissions abatement strategy, continuing adaptation and review of policies, actions and lifestyles. This study addresses all greenhouse gases, including HFCs, PFCs and SF6 and all sectors of the economy. The consultancy study, together with inventories and projections compiled by the EPA will facilitate the putting in place of the necessary measures to limit and/or reduce these emissions (Dempsey, 1998).

A report on greenhouse gases compiled by the Economic and Social Research Institute in November 1997 advocates the application of the polluter-pays-principle and of fiscal measures, such as a carbon tax to all sectors. With regard to the farming sector the ESRI states that it should not be insulated from policy changes and that that the sector's contribution to could be reduced by shifting market supports away from livestock (Irish Times 13/11/97).

4.6. Summary and Conclusions

References

Alexander, R (1989): Wildlife in the Countryside. - in: Gillmor, D (ed.)(1989): The Irish Countryside - Landscape, Life, History, People. Wolfhound Press, Dublin, p.49-82.
An Foras Forbatha (1972): An investigation into the effects of fertiliser application on limestone grassland in the Burren, Co. Clare. unpubl.; Dublin.
An Foras Forbatha (1981): Areas of Scientific Interest in Ireland. Stationary Office, Dublin
Baldock, D (1990): Agriculture and Habitat Loss in Europe. WWF International CAP Discussion Paper Number 3. London.
Baldock, D., Hermans, B., Kelly, P., and Mermet, L (1984) Wetland Drainage in Europe: The Effects of Agricultural Policy in four EEC countries. Institute for European Environmental Policy and Institute for Environment and Sustainable Development.
Bauer (1989): Grenzen des ‘Rote Liste Instruments’ und Möglichkeiten einer alternativen Bewertung von Biotopen. - in: Blab & Nowak (1989) 95-106 Zehn Jahre Rote Liste gefährdeter Tierarten in der Bundesrepublik Deutschland. Schr.R.f. Landschaftspflege und Naturschutz. BFANL. Bonn-Bad Godesberg.
Beintema, A J & deBoers, T F (1982): Verstoring von Weidevogellegsels door weidend Vee. - in: Mitteilungen der LOELF (3) 35-55
Buckwell, A (1989): Economic Signals, Farmers' Responses and Environmental Change. Journal of Rural Studies, Vol. 5, No. 2, 149-160. Great Britain.
Burdon, D J (1986): Hydrogeological Aspects of Agricultural Drainage in Ireland. - in: Environmental Geological Water Sciences, Vol. 9, No. 1, 41-65. New York
Cabot. D (1985): The State of the Environment. An Foras Forbatha, Dublin
Carton, O T, Ryan, M & W L Magette (eds) (1996): Phosphorus Recommendations for Grassland Good Agronomic Practice. Teagasc, Johnstown Castle, Wexford. December 1996.
CEC (1996): Commission of the European Communities. Communication from the Commission. Progress Report on implementation of the European Community. Programme of Policy and Action in relation to the environment and sustainable development ‘towards sustainability’. COM(95) 624 Brussels, 10.1.1996
CEC (1997): Commission of the European Communities. Report from the Commission to the Council and the European Parliament on the application of Council Regulation (EEC) No. 2078/92 on agricultural production methods compatible with the requirements of the protection of the environment and the maintenance of the countryside. Brussels, 4.12.1997. COM (97) 620 final.
Council of Europe (1981): Dry grasslands of Europe. Nature and Environment Series 21. Strassbourg.
Council of Europe (1987): Management of Europe's Natural Heritage - twenty-five years of activity. Environment Protection and Management Division. Strasbourg.
Coxon, C & Drew, D P (1986): Groundwater flow in the lowland limestone aquifer of eastern Co. Galway and eastern Co. Mayo, western Ireland. -in: Paterson, K & Sweeting, M M (eds.)(1986): New Directions in Karst. Proceedings of the Anglo-French Karst Symposium; September 1983. Geo Books, Norwich, UK, p 259-279.
Curtis, T & McGough, H N (1988): The Irish Red Data Book I Vascular Plants. Wildlife Service, Dublin.
Curtis, T G F, McGough, H N & Wymer, E D (1988): The Discovery and ecology of rare and threatened arable weeds, previously considered extinct in Ireland, on the Aran Islands, Co. Galway. - in: Irish Naturalists Journal, Vol. 22, No. 12.
Daly, D (1992): A Review of Development, Quality and Pollution Issues. - in: Feehan, J (ed.) (1992): Environment and Development in Ireland. Proc. of a Conference held at University College Dublin, 9-13 December 1991, pp 476-482. The Environmental Institute UCD, Dublin
Dempsey, N (1998) Response to Question No. 10531/98 by D. Spring. Dail Debates 6/5/98.
Department of Agriculture, Food and Forestry (1995a): International Conference and Programme for Plant Genetic Resources: Country Report - Ireland. Dublin.
Department of Agriculture and Food (1995b) Circular 9/95 To each approved REPS Planner. 21.2.95
Department of the Environment (1997): Second National Communication under the United Nations Framework Convention on Climate Change.
Drew, D (1990): The Hydrology of the Burren, Co. Clare. - in: Irish Geography 23(2) 69-89
Drew, D (1996): A Survey of Recent Reclamation in the Burren. Unpubl. report. Heritage Council, Dublin 1996
EAAP (1997): European Association For Animal Production (EAAP) Database. Commission of Animal Genetics at the Department of Animal Breeding and Genetics, School of Veterinary Medicine Hannover, Germany. URL http://www.dainet.de/genres/genreadk/tgr/tgr_i2.html
EC (Council of the European Communities) (1992): Council Directive 92/43/EEC of 21 May 1992 on the conservation of natural habitats and of wild fauna and flora. Official Journal NO. L 206 , 22/07/1992
EPA Environmental Protection Agency (1997): State of the Environment - Inland Waters. Extracts from ‘State of the Environment 1996’ URL: http://www.compass.ie/epa
EPA Environmental Protection Agency (1996): Water Quality in Ireland 1991-1994. Wexford.
European Commission (1997): Agriculture and Environment. Working Notes on the Common Agricultural Policy. Directorate General for Agriculture, Brussels
Feehan, J (ed.) (1992): Environment and Development in Ireland. Proc. of a Conference held at University College Dublin, 9-13 December 1991. The Environmental Institute UCD, Dublin.
Frieben, B (1990): Bedeutung des organischen Landbaus für den Erhalt von Ackerwildkräutern. - in: Natur und Landschaft, 65. Jg. (1990) H7/8, 379-382. Stuttgart
Gardiner, M J & Burke, W (1983): Soil erosion and conservation measures in Ireland. - in: Prendergast, A G (ed.; 1983): Soil erosion. CEC Report EUR 8427 EN; p 53-57
Government of Ireland (1997): Sustainable Development - A Strategy for Ireland, Department of the Environment, Dublin
Hickie, D (1990): Forestry in Ireland- Policy and Practice. An Taisce Publication, Dublin.
Higgins, M D (1997): Dail Motion of Designation of Special Areas of Conservation Dáil Eireann, Wednesday 13 March 1997 by Minister Michael D. Higgins, Dublin.
Irish Times 13.11.97 'ESRI report calls for tax on greenhouse gases'
IUCN (1980): World Conservation Strategy - Living Resource Conservation for Sustainable Development; IUCN/WWF/UNEP/FAO/Unesco. Gland/Switzerland
JNCC Joint Nature Conservation Committee (1992): Red Data Book of Britain and Ireland. Peterborough.
Lee, J (1995): Some Aspects of Sustainability as Applying to Agriculture in Ireland. Presented at the National Sustainability Indicator Forum, University College Dublin, April 18-19, 1995. Johnstown Castle, Wexford
Marine Institute (1997a): Fish kill summary data 1983 to 10/12/97. Data Sheet. Fisheries Research Centre, Abbotstown, Dublin
Marine Institute (1997b): Fish kills 1997 - Reports received by 10/12/97. Data Sheet. Fisheries Research Centre, Abbotstown, Dublin
Marine Institute (1997c): Fish kills 1996. Data Sheet. Fisheries Research Centre, Abbotstown, Dublin
Mayes, E & Stowe, T (1989): The Status and Distribution of the Corncrake in Ireland 1988. - in: Irish Birds 4, 1-12. IWC Dublin.
Murphy, J. (1995) Sheep, forestry and turf saving take toll on upland birds. IWC News, Vol. 82, Spring 1995.
McGrath, D (1994): unpublished data, Johnstown Castle, Wexford. - cited in Lee, J (1995): Some Aspects of Sustainability as Applying to Agriculture in Ireland. Presented at the National Sustainability Indicator Forum, University College Dublin, April 18-19, 1995. Johnstown Castle, Wexford
McNeely, J A (1988): Economics and Biological Diversity - Developing and Using Economic Incentives to Conserve Biological Resources; IUCN, Gland/Switzerland
Miklas, M (1998): Recovering Traditional Irish Cereal Varieties. Irish Seedsaver Association Newsletter, Spring 1998. Scariff.
Minister for Agriculture and Food (various years): Annual Report, Stationary Office, Dublin.
Morgan, R P C & Rickson, R J (eds.)(1988): The EC network: a catalogue of institution research workers and research projects concerned with soil erosion and soil conservation in the European Community. CEC Report EUR 11388 EN.
Moriarty, C (1996): Fish kills in Ireland in 1994 and 1995 - Reports received by 10/12/97. Data Sheet. Fisheries Research Centre, Abbotstown, Dublin
Nairn, R G W & Sheppard, J R (1985): Breeding waders of sand-dune machair grasslands in north-west Ireland. Irish Birds 3 (1): 53-70
Nairn, R G W, Herbert, I J & Heery, S (1988): Breeding Waders and other wet grassland birds of the River Shannon Callows, Ireland. - in: Irish Birds( 3) 521-537.
NCC (1990): Nature Conservation and Agricultural Change. Focus on Nature Conservation Series No.25. Peterborough.
NPWS National Parks & Wildlife Service (1995): Development of management plans and emergency actions aimed at candidate SAC's. (LIFE95 NAT/IRL/000822), NPWS, Dublin.
O'Donnell, C (1996) Pesticides in Drinking Water: Results of a Preliminary Survey December 1994 - December 1995. Environmental Protection Agency, Wexford. Cited in: Government of Ireland (1997): Sustainable Development - A Strategy for Ireland, Dublin
O'Riordan, E G & Dodd, V A (1992): Sludge - its management and disposal. - in: Feehan, J (ed.) (1992): Environment and Development in Ireland. Proc. of a Conference held at University College Dublin, 9-13 December 1991, pp. 303-311. The Environmental Institute UCD, Dublin.
Peterson, R (1983): A Field Guide to the Birds of Britain and Europe. Collins, London
Plachter, H (1991): Naturschutz. G. Fischer Verlag, Stuttgart
Poulton, P R, Tunney, H & A E Johnson (1995): Comparison of Teagasc (Ireland) and MAFF (England and Wales) fertiliser P recommendations. - in: Phosphorus Loss to Water from Agriculture, International Workshop 27-29 September, 1995, Johnstown Castle, Wexford. Quoted in: EPA (1996).
Raskin, R, Glück, E & Pflug, W (1992): Floren- und Faunenentwicklung auf herbizidfrei gehaltenen Agrarflächen - Auswirkungen des Ackerrandstreifenprogramms. - in: Natur und Landschaft, 67. Jg. (1992) H 1, 7-14. Stuttgart
Ratcliff, D A & Thompson, D B A (1988): The British Uplands - their ecological characteristics and international significance. - in: Usher, M B & Thompson, D B A (eds.; 1989): Ecological Change in the Uplands. Blackwell Scientific Publ. (Spec. Publ. No. 7 of the Brit. Ecol. Soc.), 9-36.
Ratcliff, D A (1976): Observations of the breeding of golden powers in Great Britain. - in: Bird Study 23, 63-116
RSPB - Royal Society for the Protection of Birds (1991): A Future for Environmentally Sensitive Farming. RSPB Submission to the UK Review of Environmentally Sensitive Areas 1991. Sandy, Bedfordshire, UK.
Ryan, T D (1986): Agricultural Drainage Practices in Ireland. - in: Environmental Geological Water Sciences, Vol. 9, No. 1, 31-40. New York.
SEPA Scottish Environment Protection Agency (1997): SEPA Warns of Environmental Dangers of Sheep Dip. Press release 23/97.
Sherwood, M (1992): Weather, Soils and Pollution from Agriculture. AGMET; Teagasc, Wexford.
SRU (1985): Sondergutachten des Rates von Sachverständigen fuer Umweltfragen (1985): Umweltprobleme der Landwirtschaft. Drucksache 10/3613; Deutscher Bundestag; Bonn. (‘Comprehensive and detailed global review on agriculture and the environment’)
Sukopp, H (1981): Veränderungen von Flora und Vegetation. - in: Beachtung ökologischer Grenzen bei der Landbewirtschaftung - NF Sonderheft, 197, 255-264
Temple-Lang, J & D Hickie (1992): The Wildlife Act and European Community Conservation Measures - An Up-to-date Review. - in: Feehan, J (ed.) (1992): Environment and Development in Ireland. Proc. of a Conference held at University College Dublin, 9-13 December 1991. The Environmental Institute UCD, Dublin.
Thomas, J. & Lewington, R. (1991). The Butterflies of Britain and Ireland, London: Dorling Kindersley.
Thorn, R & C. Coxon (1992): Nitrates, Groundwater and the Nitrate Directive. - in: Feehan, J (ed.) (1992): Environment and Development in Ireland. Proc. of a Conference held at University College Dublin, 9-13 December 1991, pp 483-486. The Environmental Institute UCD, Dublin
Thorn, R (1991): Comments on the water supply and liquid waste disposal aspects of the proposed visitor centre in the proposed Burren National Park, Co. Clare, Ireland. - in: The case for an independent and comprehensive impact assessment of a visitor/interpretation centre at Mullaghmore for the Burren National Park in Co. Clare, Ireland. Submitted to DG XI by the Burren Action Group, Plantlife, An Taisce, World Wide Fund for Nature, 19.7.1991.
Tunney, H (1990): A note on a Balance Sheet Approach to Estimating the Phosphorous Fertiliser Needs of Agriculture. Irish Journal of Agricultural Research 29, 149-154. Quoted in Carton, O T, Ryan, M & W L Magette (eds) (1996): Phosphorus Recommendations for Grassland Good Agronomic Practice. Teagasc, Johnstown Castle, Wexford. December 1996.
Vida, G (1978): Genetic Diversity and Environmental Future. - in: Environmental Conservation, Vol. 5, No.2, 127-132.
World Conservation Monitoring Centre (1995): Biodiversity: An Overview. World Conservation Monitoring Centre, Cambridge, UK, December 1995
Webb, R (1988): The Status of Hedgerow Field Margins in Ireland. - in: PARK (ed.; 1988)
Whilde, A (1991): Farming in the Republic of Ireland. - in: Curtis D J et al. (1991): Birds And Pastoral Agriculture in Europe. Proceedings of the Second European Forum on Birds and Pastoralism, Port Erin, Isle of Man, 26-30 October 1990
Whilde, A (1993): Threatened mammals, birds, amphibians and fish in Ireland. Irish red data book 2: vertebrates. HMSO, Belfast.
Wilcox, B A (1982): In Situ Conservation of Genetic Resources: Determinants of Minimum Area Requirements. - in: McNeely, J A & K R Miller (1984): National Parks, Conservation and Development (The Role of Protected Areas in Sustaining Society). Proc. of the World Congress on National Parks, Bali, Indonesia, 11-22 Oct. 1982. IUCN. Washington D.C.
Wildlife Service (1989): Index to Areas of Areas of Scientific Interest; unpublished.
Personal Communication
Waldren, S., Trinity College Botanic Gardens, pers. comm. December 1997
Duff, N., IWC Corncrake Field Worker, pers. comm. 1992