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Action for Scotland's Biodiversity

7 MOUNTAINS, HEATHS AND BOGS

Introduction

The mountains, moorlands and peatlands of Scotland have a powerful hold on the imagination of its people and the visitors to the country. They are an important part of Scotland's economic resource. This is as true for agriculture, forestry and field sports as it is for tourism, now the biggest industry in Scotland. It must also be remembered that peat provides a vital ingredient in the distilling of whisky. These habitats are under pressure from different land uses and have become degraded with serious consequences both for some land uses and for biodiversity.

The main impression of our mountains, heaths and bogs is of wild, open country. The visitor's impression of these ancient and apparently timeless hills must be that it was always so, but for many of the hills this was not the case. In geological terms the landscape we look at in the Highlands, though ancient from the point of view of its rocks, is young so far as its post-glacial landforms are concerned. The ice sheets of the last glaciation left it only 10,000 years or so ago, leaving behind an altered river pattern, and lochs and glens scoured by the ice. This landscape with its sandy, gravelly, humps and bumps (moraines and drumlins), set among the rounded hills, bears witness to the erosive and redistributive powers of ice and water.

By 8,000 years ago, between 60 per cent and 70 per cent of the land of Scotland was wooded, with a tree line that extended in the Eastern Highlands to about 850 m above sea level. By 5,000 years ago the combination of a wetter climate and the impact of man's activities as farmer and grazier had started the process of deforestation that created the moorlands and bogs. There will always be disagreement about the extent to which climate or human activity accelerated the development of the great peat bogs of the north-west Highlands at the expense of the forests. It is clear, however, that for the most part the moorlands of the Highlands and the Southern Uplands are kept open by land management practices. As such they are artefacts and a part of what we have come to call the cultural landscape. They are not pristine, natural ecosystems; they are distinctive and in several respects unique

Description of Key Habitats

Mountains

Scotland has more than 90 per cent of the mountainous habitat of the United Kingdom. It rises above the original tree line (the maximum altitude at which trees can grow) and represents some of the most natural and least disturbed habitats in the British Isles. The highest place in the Highlands with something approaching a natural tree line is at Creag Fhiaclach in the Cairngorms (c 625 m), but mostly the tree line is lower (not more than 500 m above sea level). In parts of the West Highlands and Northern Isles, the plant and animal communities of the montane zone can occur almost down to sea level, as a result of exposure to extreme weather.

Beneath the tree line, there may be a zone in which, because of exposure and climate, trees such as Scots pine, juniper, rowan and willows can only grow in a low, twisted, shrubby form. Unfortunately, this natural montane scrub zone is almost absent from Scotland's hills as a result of burning and grazing by hill sheep and deer.

Above the tree line, heather dominates heaths to about 750 m and then begins to give way to mosaics of dwarf shrub heath, moss heath and grassland. These, in turn, are replaced on the high plateaux, such as the Cairngorms, by a close sward of woolly fringe moss. Associated with the high level heaths are spring flushes, rock crevices and screes, each with its characteristic plant and invertebrate animal community. Montane willow scrub grows in some of these places; it is a rare type of scrub occurring notably at Creag Meagaidh, Caenlochan and Ben Lawers. Freshwater seepages, rills, streams and pools provide another range of habitats, each in turn with its own specialist community of plants and invertebrate animals. Late-lying snow patches have a specialist flora of mosses and lichens. There is relatively little mammal life on the high tops that is not more active lower in the hills, but some birds are especially associated with the summit plateaux because they breed there. These include the ptarmigan, golden plover, purple sandpiper, snow bunting and dotterel.

Dotterel - a species without a Species Action Plan

box 7.2

Threats to high altitude breeding birds like dotterel include habitat loss from climate change Dotterel are summer visitors to Scotland, arriving from their North African wintering grounds in late April to breed on the high mountain plateaux. Breeding roles are reversed with the less brightly coloured males incubating the eggs and caring for the young. Nests are built on the ground amongst alpine plants and mosses and are therefore vulnerable to trampling and especially to heavy grazing by sheep and deer. One of the most significant threats to the dotterel is climate change. The montane habitat of the high mountain tops in Scotland is one of the few habitats at risk of extinction as a result of global climate change. This could lead to the loss of breeding dotterel and snow bunting in this country. Pollution, resulting in increased acid rain in the uplands, is also a concern and may have been largely responsible for the major historic declines in dotterel numbers throughout the UK. Scottish Natural Heritage has undertaken long term intensive studies to improve our understanding of the ecology of the dotterel, including threats to its population size and its requirements for breeding. Almost half the population occurs in designated, internationally important wildlife sites. Further work is required to control grazing pressure on the breeding habitat. National efforts to reduce emissions of carbon dioxide and airborne pollutants are urgently required to address in part the threats from climate change and acid deposition.

Other species, like the yellow marsh saxifrage, need moderate grazing to prevent scrub out-competing them	Scotland's famous heather moorlands support a characteristic range of plants and animals. The illustration shows the heather or ling.

Heathland

Below the montane zone lies heathland, covering an estimated 1.7 to 2.0 million ha. Generally, this is found where the precipitation is more than 100 cm per year, and where the soil is poor and acidic or peaty. Heathers, including ling, which bring the characteristic blaze of purple to the hills when it flowers in August, are the dominant plants. Growing among the heathers, in the vegetational mosaic that is moorland, are other members of the heather family (Ericaceae) such as blaeberry, crowberry and bearberry. Other characteristic flowering plants include heath milk-wort, tormentil, and alpine lady's-mantle at its lowest altitudinal limit. Many species of grasses, mosses, lichens and fungi also occur. Within this mosaic are other members of the upland vegetational complex, grass heaths, wet flushes and bogs of various kinds. In the north-west of Scotland, variants of heather moorland are particularly rich in mosses and liverworts, the 'wet heaths'.

Grass heaths include the fescue/bent grasslands dominated by sheep's fescue and common bent, important to farmers as nutritious hill grazing for cattle and sheep (see Chapter 5). Purple moorgrass heaths are vital habitat for voles and meadow pipit, favoured prey of the hen harrier.

Moorland is an open landscape, but scrub is an important part of the complex of habitats that make it up. Juniper, birch and willow are all necessary parts of the habitat of black grouse, a species that has been undergoing a dramatic decline over the past 20 years (see Box 7.4). Wet flushes are a vital habitat for many invertebrates. As well as its own importance for biodiversity, the invertebrate fauna is vital in the diet of young red grouse, which depend on eating the protein rich fauna of the wet flushes before they start to eat heather. Wet flushes are the habitat of many waders - snipe, peewit (lapwing), curlew, sandpiper, redshank - vocal birds of the hills. Characteristic birds of the moors include meadow pipit, twite, golden plover, merlin, red grouse and hen harrier. The mammals of the moors include the red deer, mountain hare, fox and voles.

Large areas of heathland are man-made, created out of the former understorey of pine and birch woods from which the trees were removed by humans and are now excluded by muirburn and grazing. These areas may be of considerable economic importance for field sports as managed 'grouse moors'.

Bogs

Bogs are peatlands fed only by rainwater and melting snow, as

distinct from fen peatlands which are also fed by ground water or streams. Bogs are conventionally divided into two types - blanket bogs which form a cloak over hills in the cool, moist climate and lowland raised bogs which form discrete domes in an otherwise non-peat landscape.

By far the greatest amount, about 75 per cent, of blanket peat in the United Kingdom occurs in Scotland, with around 1,100,000 ha of the habitat. It is estimated that in excess of 25 per cent of this peat soil no longer supports bog habitat due to forestry and agricultural reclamation. Lowland raised bogs develop primarily in lowland areas, such as river flood plains or heads of estuaries, where rainfall is too low to enable blanket bog to form and generally where the drainage is impeded. The peat accumulates to form a layer which can be as deep as 12 m. The preserved remains of plants, animals and occasionally human artefacts, as well windblown or volcanic deposits of use in determining climate patterns, are found within this peat.

Juniper, birch and willow are all necessary parts of the habitat of black grouse, which has declined markedly in the last 20 years	The 'Flow Country' in Caithness and Sutherland is one of the largest areas of blanket bog in the world; the photograph is of West Borgie SSSI in Sutherland

Trends of Change and Threats

The 16th century saw heathland reach its greatest extent. Since the 17th century, however, there has been a heathland decline, especially during the last half century. Afforestation, particularly the plantations of non-native conifers, has replaced heather as the dominant vegetation of large stretches of country. Similarly, the reseeding of heather moorland with grasses to improve pastures for sheep, coupled with liming and slagging (the spreading of phosphates), have changed the vegetation. Localised heavy grazing has contributed to this process, as has the increase in numbers of deer. In addition, uncontrolled or poorly practised muirburn has been a significant factor in recent years.

Peatbogs have seen similar reductions due to the activities of forestry and agriculture, but there have also been pressures due to commercial and domestic peat cutting. One of the most significant issues at present is the deterioration of bogs which have been damaged in the past by drainage associated with agriculture, forestry and mechanical peat extraction. Positive management is now urgently required to restore water levels and to bring the bog habitats 'back to life'. Whereas there are considerable stretches of blanket bog that have not been damaged, it is unlikely that there is any lowland raised bog in Scotland that has not been damaged, at least to some extent.

Montane species are particularly vulnerable to the effects of climate change and acid rain. Addressing these issues requires action both by Governments and by all of us as individuals. It is essential that air pollution and emissions of greenhouse gases are reduced as a matter or urgency.

Diagram of Scotland's land cover change: from the National Countryside Monitoring Scheme	box 7.6

Summary of Main Objectives and Proposed Actions

Action plan objectives seek largely to maintain the remaining areas of those habitats which are in good condition and to restore some of the damaged areas so that they can function again and support their full complement of species. Each of the Species and Habitat Action Plans contain targets, and these obviously vary from plan to plan. However, there are some recurring themes, and these are highlighted in the following sections.

Muirburn

Until the second half of the l9th century burning of moorland to 'improve' the grazing for livestock was mostly done in a relatively uncontrolled way. In the last century the increasing value of grouse shooting led to a much more rigorous approach to moorland burning. Moorland managed in this way has proved to be good habitat for a range of bird species. However, while it holds the heather in a vigorous juvenile stage, other species of plant that are sensitive to fire do not thrive on moors which are periodically burned. Poorly managed muirburn may, for example, be detrimental to the plant communities, which consist of mosses, liverworts and lichens, that occur below the heather.

The frequent burning of moorland inhibits the development of the birch, willow and juniper scrub that are so important for black grouse and some other species with species action plans. The black grouse has undergone a catastrophic decline in numbers in the last 30 years.

Muirburn should not be a part of the management of the montane zone. The harsh mountain environment does not allow the vegetation to recover in the way that it can lower down the hill. Muirburn should also be confined to the drier heaths because, in the wetter conditions of the west of Scotland, the heather can regenerate naturally by layering.

With the right support and advice, managers of large upland estates will continue economic activity on heather moors in a way which safeguards the sensitive areas for biodiversity. Agri-environment schemes must also encourage 'best practice' burning methods.

Red deer numbers have increased greatly over the last 30 years, with inevitable effects on tree regeneration and moorland vegetation

Deer and Sheep Grazing

The definition of overgrazing depends on the management objectives for an area of land. Some habitats such as heathland can benefit from limited grazing to prevent encroachment from trees. If, however, grazing pressure is too great the habitat can become damaged and lose some of its wildlife interest.

The increase in numbers of red deer, from some 180,000 in 1970 to about 320,000 in 1997, has had a considerable impact on upland habitats. Among the reasons for the increase in deer numbers are the mild winters in the 1980s, allowing better survival, the provision of salt licks and supplementary feeding, as well as low venison prices. The way forward for biodiversity lies in properly managing and controlling deer numbers in order to maintain and restore bog, moorland and heath habitats. It is important that the Deer Commission for Scotland, together with the Deer Management Groups, play a role in conserving biodiversity through effective deer management.

There has also been a general increase in numbers of sheep in upland areas over the last 50 years, though there is considerable geographical variation. In situations where numbers have stabilised, the density of sheep has increased through, for example, conversion of grazing land to forestry. Farmers and crofters have found it difficult to reduce sheep numbers as subsidies are at present paid on a headage basis. Problems from overgrazing are also connected with lack of shepherding - economics have forced sheep farmers to employ fewer shepherds. Fifty years ago a hill shepherd was expected to look after five hundred ewes; by the end of the 20th century he is expected to look after between one and two thousand.

Farmers and crofters are increasingly being offered financial support to ensure appropriate grazing levels. Examples are the agri-environment payments, management scheme payments and forestry grants. In the longer term, changes are being considered for livestock subsidies to enable better compliance with biodiversity objectives.

Drainage

Extensive tracts of peatland have been drained in an attempt to improve the quality of grazing. These drains can continue to cause lowering of the water table for many years and result in damage to the bog habitat. They can also be detrimental to the grouse interest as they are suspected of reducing the number of invertebrates, the food of grouse chicks in the first few days of their lives. Agri-environment schemes could be designed to help to repair areas damaged by drainage.

Forestry

Afforestation has resulted in the reduction of heath and peatland habitats, but forestry policy, through indicative forestry strategies, now guides new planting towards less sensitive sites. In addition, the Environmental Impact Assessment Regulations require much wider consultation procedures leading to better informed decisions. Restructuring of forests provides the opportunity to alleviate some of the pressure on sensitive areas and to restore more open habitat. To achieve the objectives of the UK's Biodiversity Action Plan there needs to be a 'reasonable balance' between the various land uses. In relation to forestry, achieving a 'reasonable balance' is now a statutory requirement.

Peat Extraction

The extraction of peat or underlying mineral deposits can have major implications for peatlands. Commercial mining of peat, for fuel and horticulture, or for underlying minerals such as coal, causes irreversible damage to peatland systems. Encouraging the development and use of alternatives to peat, often based on waste materials, offers a solution which retains economic and employment benefits. Domestic cutting of peat on blanket bogs is widespread, yet in only a very few instances does it have significant impacts on wildlife. Codes of practice for domestic peat cutting could help avoid the most damaging effects on biodiversity, though it must be recognised that careful cutting, maintaining the actively-growing vegetation, can re-start an ecological succession and aid biodiversity.

Global warming may result in the loss of some arctic-alpine plants such as Gentiana nivalis

Recreation

Even a cursory glance at the hills will show the impacts of access on the countryside. There are few hills over 705 m (2,500 feet), and certainly none over 915 m (3,000 feet), that do not have a highly visible path leading to the summit. The development and expansion of tracks, for recreational and sporting activities, have posed problems for countryside managers in the last 40 years. In the fragile montane environment it is easy, relatively speaking, to dig a track for a vehicle, but the harsh environment of the mountains means that recovery of the surrounding vegetation is extremely slow. The new tracks, whether caused by trampling feet or built to provide vehicular access to the hills, cause erosion and both the soils and the mountain biodiversity suffer.

Acidification and Global Warming

The long term effects of pollution, such as acidification, nitrogen enrichment and global warming, are going to have impacts on montane and moorland habitats. Global warming with its consequent climatic instability may result in the loss of species of plants and animals, particularly the arctic-alpine species (and notably some of the rarer plants that are found on Ben Lawers, Glen Coe and Caenlochan). If they are lost from Scotland these species will be unable to recolonise if the climate once again becomes cooler, unless they are re-introduced from Scandinavia. The full implications for upland habitats are not known, but it is clear that the resource should be brought into as good a condition as possible to help it withstand any climate change impacts. Equally, it is important to ameliorate the factors which are thought to be responsible for human-induced changes to the climate.

The conservation of mountain and moorland habitats depends on better public awareness and understanding of the issues. Tourism and recreation have a vital role to play in promoting the biodiversity of our mountains and peatlands, but they must be managed in a way that does not damage the very features that people have come to enjoy.

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