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Towards a strategy for Scotland's biodiversity
THE RESOURCE AND TRENDS

1. SCOTLAND'S BIODIVERSITY RESOURCE

James Curran, Ian Fozzard, Mary Gibby, Ed Mackey, Scot Mathieson, Ian Walker and Jeremy Wilson

1.1 Introduction

In preparing a Scottish strategy for the protection and enhancement of biodiversity, it is essential first to determine the starting point and priorities for action. This chapter attempts to define the present status, according to the Convention on Biological Diversity (CBD) definition of biodiversity in terms of habitats, species and genetic resource.

1.2 Habitats

1.2.1 Diversity of habitats

For its size, Scotland possesses a mixture, diversity and close inter-relation of habitats that is particularly unusual and worthy of protection. These mosaics create high landscape value and are the essence of Scotland's natural beauty.

Significant hotspots for species richness occur in Scotland. The richest areas occur in Argyll, the Breadalbane Hills, the Central Highlands, Mull and Skye. Scotland contains 65 of the 169 habitats listed within the European Commission's Habitats Directive, including some for which Scotland is globally important. The rest of the UK adds only a further 15 such habitats (Miles et al., 1997). Species richness is likely to reflect the local diversity of habitats which form complex mosaics in these areas with high spatial variability of geology, drift and soil materials, coastal features, topography, climate, and land management activities.

1.2.2 Terrestrial habitats

Around 40 per cent of Scotland has been classed as upland in character, and a further 33 per cent as marginal upland (McGowan et al., 2001). Mountains therefore exert a considerable influence on Scotland's visual and ecological distinctiveness. On the higher mountain tops, the montane plant communities represent southern and oceanic outliers of arctic-alpine fellfield and mountain tundra. Prostrate Calluna vulgaris heath above the natural tree-line, with a varying abundance of lichens, mosses and liverworts, is rare elsewhere. Racomitrium heath on the summit plateaux and erosion surfaces are absent from the continental European mountains (Ratcliffe & Thompson, 1988).

Blanket bog cloaks much of the Scottish uplands, accounting for a quarter of the overall land area (Haines-Young et al., 2000). This habitat is more extensive and varied in Scotland and Ireland than elsewhere in Europe (Lindsay et al., 1988). In the lowlands, Scotland also retains one of the richest surviving European concentrations of raised bog. Bogs support an especially rich diversity of invertebrates and dense populations of breeding waders, particularly dunlin ( Calidris alpina) and golden plover ( Pluvialis apricaria) .

Many highly valued Scottish landscapes and habitats have evolved through low intensity farming activities, for example crofting and extensive sheep rearing (Beaufoy et al., 1994). The mosaic of habitats thus created sustains a diversity of plants, invertebrates and birds, especially on the botanically-rich machair coastal grasslands. The densities of breeding wading birds - mainly redshank ( Tringa totanus), snipe ( Gallinago gallinago), dunlin ( Calidris alpina), ringed plover ( Charadrius hiaticula) and oystercatcher ( Haematopus ostralegus) - on the machairs of the Uists and Tiree are unsurpassed in Europe. The breeding wildfowl of the machair lochs includes large numbers of native greylag geese ( Anser anser). Acid grasslands, which predominate towards the wetter west, and dwarf shrub heath on drier, freely drained soils to the east, have been sustained by grazing and burning since the natural forest was cleared from Neolithic times onwards. Together, they cover about a fifth of the land area (Haines-Young et al., 2000).

Heather moorlands are distinctive and remarkable for their beauty and economic value, wild plants and animals. Within Europe, they are now extensive only in the British Isles, and particularly in Scotland (Thompson et al., 1995). Moorland is an important breeding or feeding habitat for 57 bird species, of which 12 are of European importance. Moorlands in the UK support exceptionally high densities of red grouse ( Lagopus lagopus scoticus), a distinctive endemic race of the willow grouse, golden plover ( Pluvialis apricaria) and hen harrier ( Circus cyaneus).

At 17 per cent of the Scottish land area, forest and woodland cover is relatively, but not exceptionally, low by European standards. The Caledonian pine/birch-dominated forests, which have a smaller range of species than continental boreal forests, contain several plant and animal species which are rare or absent elsewhere in the UK (e.g. twin flower, Linnaea borealis, capercaillie Tetrao urogallus, and the shining guest ant, Formicoxenus nitidullus). The western oakwoods are also special with their epiphytic communities of non-vascular plants (mosses, liverworts and lichens).

Although built-up land accounts for only around 3 per cent of the total land area (Haines-Young et al., 2000), some 80 to 90 per cent of the Scottish population encounters the natural world most frequently in and around settlements. Greenspace ranges in extent from around 10 to 40 per cent of the major Scottish towns and cities, but little is known about qualitative attributes such as composition, wildlife, connectivity, tranquillity and accessibility. Areas of semi-natural habitats can often survive within towns along rivers and burns, fragments of ancient woods, moors and wetlands. Where semi-natural habitats are conserved, or restored, a diversity of plants and animals can flourish. Environmental improvements have allowed the Atlantic salmon ( Salmo salar) and otter ( Lutra lutra) to re-colonise parts of the Forth and Clyde river systems that were grossly polluted in the recent past. The Central Scotland Woodland Initiative is improving the environment and landscape of the Central Lowlands, formerly degraded by mining and heavy engineering industries. The restored Lowland canal network has reinstated a corridor of waterway and greenspace, for recreation and wildlife, between towns across central Scotland.

1.2.3 Freshwater habitats

More than 2 per cent of the Scottish land surface is covered by fresh waters including some 28,000 standing waters, over 50,000 km of flowing waters, and 220 km of canals. The mountainous topography, hard, slow-weathering acidic geology, high rainfall and acidic soils of Scotland's large upland areas mean that much of Scotland's freshwater resource has clean, clear waters with low nutrient levels. Exceptions are to the south and east of the Highland boundary fault, and where isolated pockets of base-rich rocks are available for weathering, such as the Caithness limestone (Maitland et al., 1994).

Scotland's river resource is dominated by high energy, gravel bed-rivers which are a global stronghold for the Atlantic salmon and the freshwater pearl mussel ( Margaritifera margaritifera). Many other animals and plants associated with riverine habitats are identified as conservation priorities in the UK and in Europe including river jelly lichen ( Collema dichotomum), otter, the lampreys ( Petromyzon marinus, Lampetra fulviatilis and L. planeri), and several species of Diptera and Coleoptera.

The over-riding importance of Scotland's lochs in terms of biodiversity is their scale, their range of habitats and species, and their high quality. They contain over 90 per cent of the UK's standing water resource, including 14 of the UK's 15 largest standing waters. Scotland's loch resource is dominated by low-nutrient Highland lochs and lochans, which support high quality macrophyte and invertebrate assemblages, unique populations of Arctic charr ( Salvelinus alpinus), whitefish such as powan ( Coregonus lavaretus), and many bird species, including divers ( Gavia spp.). Scottish lochs also support other rare plant species, such as American pondweed ( Potamogeton epihydrus), and nationally scarce plants such as six-stamened waterwort ( Elatine hexandra).

Scotland is also the principal location in the UK for mesotrophic lochs, moderately nutrient-rich lochs which are the most botanically diverse standing waters, with around 275 sites identified to date. Scottish mesotrophic lochs hold all of the UK populations of the rare water plants slender naiad ( Najas flexilis), Shetland pondweed ( Potamogeton rutilis) and various stonewort species (e.g. Chara and Nitella spp.).

Ponds support a diverse and abundant biodiversity, beyond what might be expected for their small size. The shallow waters of Scotland's ponds and pools are home to a wide variety of species including a number of rare invertebrates such as the medicinal leech ( Hirudo medicinalis). This species is found only in a few shallow weedy nutrient-rich lochs. Another rare invertebrate, the northern blue damselfly ( Coenagrion hastulatum) is confined to the shallow waters of a few weeded pools in three small areas of Scotland. The great crested newt ( Triturus cristatus) is also found in discrete areas of Scotland, with perhaps the largest concentrations of breeding ponds in Dumfries and Galloway and in the Central Lowlands.

Wetland habitats associated with fresh waters are principally fens, reedbeds, and some remnants of wet woodland forming natural transition zones between the open waters and grassland or woodland habitats. Apart from the Insh Marshes on the Spey (the UK's largest continuous area of base-poor fen) and the reedbeds fringing the lower reaches of the River Tay, they are generally relatively small remnant habitats compared with Scotland's rivers and lochs.

1.2.4 Coastal habitats

Scotland's large firths and estuaries are of international significance as habitats for wading birds and waterfowl, such as wigeon ( Anas penelope), teal ( A. crecca), dunlin and knot ( Calidris canutus). The extensive mudflats contain remarkably high densities of worms, molluscs and crustaceans, all of which provide food for birds and fish. Eelgrasses ( Zostera spp.) are unusual flowering plants with adaptations to salt water. Two species (one with two distinct varieties) are found in Scotland on shallow sand or muddy sand sediments. The Cromarty Firth hosts the largest known stand of dwarf eelgrass ( Zostera noltii) in the UK. Saltmarsh dominates the Solway coastline, with 10 per cent of the total UK area of the habitat.

A number of important saltmarsh plants, such as rock sea lavender ( Limonium binervosum aggregate), reach the northern limit of their distributional range in the Solway. Saltmarsh vegetation provides food for internationally important populations of wintering geese, particularly the barnacle goose ( Branta leucopsis) and dark-bellied brent goose ( B. bernicla bernicla), and breeding areas for wading birds such as redshank. Only relatively narrow areas of saltmarsh are found in east coast estuaries although the reed beds of the Tay Estuary are the largest continuous stand of this habitat in the UK. In Scotland, saltmarsh has special conservation significance wherever there is a complete transition in zonation from the saltmarsh to terrestrial habitats, such as woodland, grassland or dune. Complete ecological transitions are rare in other parts of the UK due to land use for development and agriculture and hence these transitions in Scotland are ecologically very important.

An essential feature of sand dunes is their dynamic nature and Scotland has a great variety of dune systems. Dune systems in the Western Isles include the best examples of the machair habitat, formed by coastal grasslands on wind-blown shell sand. Juniper ( Juniperus communis) forms lichen-rich dune scrub at three sites in Scotland: Morrich More in the Moray Firth, Coul Links, just north of Dornoch, and Invernaver on the north coast. The natterjack toad ( Bufo calamita), which has suffered a substantial decline in numbers and range during the 20th century due to habitat loss, lives in the sand-dune habitat on the Solway Coast, now the northern limit of its British range.

Saline lagoons are coastal water bodies with only limited connection to the sea and are internationally important priority habitats due to their rarity and unique species assemblages. Scotland has 139 lagoon sites, with most in the Outer Hebrides, Orkney and Shetland. Characteristic lagoon communities include priorities such as five species of stonewort and the lagoon sea slug (Martin et al., 2002).

The combination of offshore islands, indented sea lochs and tidal straits creates the conditions for the full range of rocky shore habitats, from extremely exposed Atlantic shores to extremely sheltered areas within sea lochs. As a result, Scotland has one of the most diverse rocky coastlines in the world. High coastal cliffs are a feature of the north and west of Scotland, particularly in the Outer Hebrides and Northern Isles. In close proximity to productive coastal waters, these provide the breeding sites for internationally significant concentrations of seabirds.

1.2.5 Marine habitats

The seas around Scotland support a varied and rich wildlife. The North Atlantic Drift brings warm waters to the west coast and cold sub-Arctic waters reach down to the Northern Isles, bringing together northern and southern marine species. The range of exposures to currents and wave action, and the varied geology, make Scotland's marine and coastal habitats among the most diverse in the world.

Underwater rock surfaces are frequently colonised by kelp Laminaria forests which fringe many parts of the Scottish coast. Kelp forests support a wide range of algal and faunal species, including sea anemones, sponges and sea squirts, as well as more mobile species like brittlestars, sea urchins, crabs and many fish species. Rock surfaces in current-swept areas also support large numbers of algal and invertebrate species, with faunal dominance increasing with depth as light levels decrease.

Sands and gravels in inshore areas are vital nursery grounds for commercially valuable fish and shellfish. Scotland is internationally important for maerl, a collective term for several species of red seaweed which form hard 'calcified' outer casings and grow as nodules on the sea bed. Over 1,700 animal and 300 seaweed species have been recorded from European maerl beds. A recent study of invertebrates inhabiting Scottish maerl beds found species previously unknown to science. Maerl beds are particularly well developed around the Scottish islands.

Serpula vermicularis is a marine worm which secretes a hard limy tube around itself and, exceptionally, aggregates into reefs covering areas up to 1 m across. This reef form appears to be very rare and, in the UK, only now exists in one Argyll sea loch. The Loch Creran populations are thought to form the best reefs of this type in the world and the three dimensional structure of the reef provides crevices in which a host of other animals can live.

Scotland's fjordic sea lochs, such as Loch Alsh and Kyle Rhea, have some of the strongest tidal streams in the UK. The marine life associated with tidal rapids typically includes a colourful mix of soft corals, sea firs (hydroids), sea mats (bryozoans), large sponges, anemones, mussels and, where the current slackens, dense beds of brittlestars.

In temperate oceanic seas, hard corals are usually solitary but the coral Lophelia pertusa is an exception. Small patches of Lophelia have been reported from waters to the west and north-west of Scotland and, although typically found in water depths between 200 and 400 m, it may grow as deep as 3,000 m. The Darwin Mounds are a series of unique large sand mounds in the Rockall Trough which are capped with reefs of Lophelia pertusa. Colonies of Lophelia can form substantial reefs growing several metres clear of the seabed, and perhaps taking hundreds of years to form. More than 800 different animal species have been recorded living amongst live and dead Lophelia. These reefs are as rich in biodiversity as some tropical coral reefs.

1.3 Species

Scotland's species richness is similar to Nordic countries at the same latitudes (Delbaere, 1998). Usher (1997) estimated that there may be 90,000 species in the terrestrial, freshwater and near-shore marine environments of Scotland, with approximately half of these being single-celled organisms, one quarter plants and fungi, and the remaining quarter animals. Scotland's species complement is relatively unremarkable in a European context since most of it is shared with other areas of the UK and Europe. Just 31 species are currently considered to be endemic to Scotland, and some of these may yet prove to have wider distributions elsewhere.

However, the diverse mix of Atlantic, Arctic, Arctic-alpine and boreal elements found within a limited geographical area is noteworthy, and includes many species on the edge of their global distributional range (Birks, 1997). Scotland's overall species resource is thus remarkable more for its unique assemblages of species than for either the sheer number or rarity of the individual species concerned. This, in part, results from the fact that Scotland has a wide spectrum of habitats rarely equalled in variety in a similar-sized area elsewhere in the world (Watling, 1997). For bryophytes, lichens, fungi, vascular plants and birds, boreal, arctic-alpine, oceanic and continental species co-occur within this diversity of habitats. Fifty-eight per cent of Europe's bryophyte species, 42 per cent of its birds and 37 per cent of its lichens are found within Scotland (Mackey et al., 2001).

The unique attributes of Scotland's biodiversity resource are here characterised both geographically (i.e by reference to species endemic to Scotland or with their world range or population stronghold in Scotland), and functionally (by reference to 'keystone', 'umbrella' or 'flagship' species indicative of the wider conservation importance or state of ecosystems and habitats). Hill et al. (2002) provide a more complete inventory of Scotland's biodiversity from a similar perspective.

1.3.1 Endemic species

Scottish beard-moss ( Bryoerythrophyllum caledonicum), Halecania rhypodiza, a lichen known only from the Ben Lawers range and Caenlochan in Angus, mountain scurvygrass ( Cochlearia micacea), Scottish primrose ( Primula scotica), Ceratophyllus fionnus, a flea found only on Manx shearwaters ( Puffinus puffinus) breeding on Rum, and Scottish crossbill ( Loxia scotica) are examples of the 31 species for which Scotland is responsible for the future of the entire global population. This list includes ten lichens, eleven vascular plants, five mosses, four insects and one bird; the species are listed in Fleming et al. (1997) and Hill et al. (2002).

1.3.2 Stronghold species

There are many species where Scotland holds the majority of the world population; these include great skua ( Stercorarius skua), gannet ( Morus bassanus), Manx shearwater, grey seal ( Halichoerus grypus), hay-scented buckler fern ( Dryopteris aemula), and wintering populations of migratory pink-footed geese ( Anser brachyrhynchus) . Scotland is also the main stronghold of an important offshore commercial species, the Norway lobster ( Nephrops norwegicus).

At a smaller geographical scale, there are also species with wider distributions whose UK or European range or population is concentrated in Scotland. For example, amongst vascular plants, several species restricted to western Europe achieve unusual dominance in Scottish vegetation (e.g. bluebell ( Hyacinthoides non-scriptus), western gorse ( Ulex gallii) and heather ( Calluna vulgaris)), and 76 of the UK's species are found only in Scotland, 45 of these being species of montane habitats (Sydes, 1997).

Young & Rotheray (1997) suggested that 1,300 of 14,000 insect species in Britain may be unique to Scotland including dragonflies such as the azure hawker ( Aeshna caerulea), and northern emerald ( Somatochlora arctica), several moths and the chequered skipper butterfly ( Carterocephalus palaemon) whose English populations are now extinct.

Over 30 annually breeding or wintering British bird species are also found exclusively, or with greater than 90 per cent of their British range or population, in Scotland. These include seabirds (e.g. great skua), raptors (e.g. golden eagle ( Aquila chrysaetos)), rails and gamebirds (e.g. corncrake ( Crex crex) and capercaillie ( Tetrao urogallus)), waders and wildfowl (e.g. greenshank ( Tringa nebularia)) and songbirds (e.g. crested tit ( Paruscristatus)).

1.3.3 Keystone species

These are species whose loss from an ecosystem would have a disproportionately large effect on other species populations or ecological processes in that system. They include, for example, heather ( Calluna vulgaris), a key dominant of heathland across Scotland. Intensive grazing and burning cause its decline in favour of grassland, yet the maintenance of heather and associated ericaceous shrubs in the upland vegetation mosaic may be critical to the maintenance of moorland biodiversity more generally. Similar key dominant plant species in other ecosystems include sessile oak ( Quercus petraea), pedunculate oak ( Quercus robur), Scots Pine ( Pinus sylvestris) and the Laminaria kelp species.

Amongst invertebrates, the common earthworm ( Lumbricus terrestris) provides a good example of a keystone species. It is one of the commonest and most widespread invertebrate species in Scotland and plays a major role in soil organic matter decomposition and nutrient cycles, influencing soil structure, fertility and productivity; it is also a key prey item for many birds and mammals.

In estuarine food webs, the majority of energy flows through the brown shrimp, Crangon crangon, which feeds on a wide range of invertebrates and is eaten by many species of bird, fish and crab. The sea urchin Echinus esculentus has a dramatic effect on the faunal and floral turf of subtidal rocks; heavy grazing can result in barren rocks covered only in pink encrusting algae with some Laminaria.

Amongst vertebrates, the meadow pipit ( Anthus pratensis) might be considered a keystone species of upland habitats; it is abundant on grass or grass/heather moorland, depends for food on terrestrial invertebrates (mainly Diptera) within these habitats and is, in turn, an important prey species for raptors such as hen harrier ( Circus cyaneus) and merlin ( Falco columbarius). Red deer ( Cervus elaphus) is a classic keystone species, strongly associated with Scotland, whose grazing and browsing affect forest regeneration and the development of tall herb communities over wide areas.

It is recognised that there is very little understanding of the importance of microbial or fungal species with equivalent keystone roles, particularly in soils and in marine waters.

1.3.4 Umbrella species

These are species requiring habitat or resource management on large spatial scales. If conservation management for these species is achieved, then many other species with smaller scale requirements within the same ecosystem will also be protected. For example, heathland dominated by bearberry ( Arctostaphylos uva-ursi) in association with heather acts as an umbrella for a wider community of scarce herbaceous species (e.g. intermediate wintergreen ( Pyrola media)), as well as a characteristic insect fauna not shared by other heathland types.

At much larger spatial scales, breeding populations of golden eagles require extensive, open upland an a good supply of prey. The species therefore serves as an umbrella for both its prey and for other species depending on open tracts of upland habitat. This species is clearly also a 'flagship' for the open, montane habitats of Scotland.

1.3.5 Flagship species

These comprise charismatic species serving as symbols and rallying points to stimulate conservation awareness and action. The freshwater pearl mussel ( Margaritifera margaritifera) is a classic flagship species. A BAP priority species, listed under the Habitats Directive and on the World Red List, this long-lived species may be affected by siltation, poor water quality, river dredging and engineering, and exploitation for its pearls. The basking shark ( Cetorhinus maximus), one of the world's largest fish, would also be a flagship species. It migrates north into Scottish waters each summer, where it feeds on the abundant supply of plankton.

A selection of other flagship species includes the Scottish primrose ( Primula scotica, a beautiful plant dependent on unimproved coastal grassland with a light grazing regime), Atlantic salmon ( Salmo salar, a fish with high public profile, serving as an emblem of pollution control and protection of stocks against excessive sea-fishing), puffin ( Fratercula arctica, a charismatic species indicative of marine conditions for the fishes on which it preys), and otter ( Lutra lutra, a species, at the top of the food chain, with high public profile and whose recovery reflects the effect of widescale reduction in aquatic pollution).

1.3.6 Postscript

Some species clearly fall into more than one of these categories. A classic example of a single species to represent Scotland is perhaps the Scots pine; a flagship emblem of the Scottish highlands whose natural populations have been reduced drastically in extent, as well as being a key dominant of native pinewoods and an umbrella species for a wide range of bryophytes, fungi, vascular plants and animals, all of which depend on the pinewood for their survival.

1.4 Genetic resources

Biodiversity includes not only habitats and species but also the genetic variation present within each species. Genetic variation comprises the variation within an individual population and the variation between different populations of the same species. This genetic variation influences the ecological amplitude of a species and its ability to evolve and adapt to changing environmental conditions, whether caused by natural or man-induced change. Knowledge of the genetic diversity of a species is desirable for its future management and conservation.

For many groups of organisms Scotland may appear to be relatively species-poor in comparison with countries from southern Europe, reflecting the effect of repeated glacial cycles in northern and western Europe. However, the species present today in Scotland are likely to have adapted to local conditions that include the rich mosaic of habitats here - woodlands, pastures, mountain tops, moors, offshore islands and open water. These local adaptations make the genetic component a significant element of Scotland's biodiversity resource (Ennos & Easton, 1997).

Populations growing at the edge of their range may show local adaptation. Experimental work has demonstrated that Scottish populations of Scots pine show greater growth in height than do continental European populations, when grown under Scottish conditions (Worrell, 1992). In trials in east Scotland, pine populations from this area show greater growth in height and resistance to local rust pathogens in comparison with populations from the west (Lines & Mitchell, 1964). This clearly demonstrates the importance of using local genetic material when undertaking any restoration or re-introduction work.

Fragmented landscapes and isolation on islands provide opportunities for adaptation through natural selection. In the Shetland Islands, adaptation in populations of field mice ( Apodemus sylvaticus) has resulted in increased body size and change in body colour (Berry & Johnston, 1980). Similarly, Scotland hosts four forms of the wren ( Troglodytes troglodytes), and one each of song thrush ( Turdus philomelos), crested tit, starling ( Sturnus vulgaris) and linnet ( Carduelis cannabina) that are considered sufficiently distinctive to merit sub-specific status (Clugston et al., 2001).

Scottish river systems support one of the largest and most diverse of the Atlantic salmon resources in Europe, with nearly 400 salmon rivers supporting many hundreds of populations, each with its own genetic distinctiveness (SERAD, 2000). Scotland is also a stronghold for Arctic charr ( Salvelinus alpinus) with perhaps 200 separate loch populations. Research shows that, following post-glacial isolation, these have become genetically distinct between, even within, lochs (Hartley et al., 1995). Each of these populations has evolved slightly differently in response to slightly different environments in each loch, with an explosion of forms and life histories which have formed in the 8,000 to 9,000 years since the glaciers retreated. The Arctic charr is an excellent example of the adaptation and development of a species. Within the species, many different morphs (or varieties) are seen. These morphs have different diets, and fit into the ecosystem at different points. They vary in colour from a tomato soup red to a drab camouflage colour. They also show different size characteristics and bone structure depending on their diet. As with Darwin's finches ( Geospiza spp. in the Galapagos Islands), this is a single species adapting to inhabit different ecological niches to such an extent that many people now regard some populations as new species (Alexander & Adams, 2000).

Molecular tools are used to explore genetic variation. These provide information on dispersal and population genetic structure which, together with knowledge of reproductive biology and demography, can contribute to the development of appropriate strategies for conservation. Stewart et al. (1999) have demonstrated a metapopulation genetic structure in the water vole ( Arvicola terrestris) in north east Scotland, with colonies showing genetic differentiation. A study of the otter across Scotland has revealed that isolation of the populations on Shetland and Orkney is associated with reduced levels of microsatellite diversity (Dallas et al., 1999). Molecular markers also provide information on current and historical distribution patterns, and have proved valuable in studying post-glacial colonisation in tree species, including alder, birch, oak and pine (Ennos et al., 1997, 2000).

Many of the Scottish vascular plant species that are listed in the UK BAPs have complex taxonomies. The use of genetic markers has proved valuable in clarifying their taxonomic status, and has demonstrated the presence in Scotland of actively evolving groups that have given, or may be in the process of giving, rise to new species. Examples include Newman's lady fern ( Athyrium distentifolium var. flexile) (McHaffie et al., 2001), Young's helleborine ( Epipactis youngiana) (Hollingsworth, 2001) and several Eyebrights ( Euphrasia spp.) (G. French, pers. comm.)

1.5 Social resource

Scotland has a long history of interest in, and understanding of, its natural heritage, drawing its strength from the cultural importance of the landscape and seascape to its people over generations. Despite industrial development, urbanisation and demographic change, there remains a strong attachment to, and identification with, the natural heritage which defines the character of Scotland. This is a valuable resource which should support and facilitate delivery of biodiversity objectives. However, public understanding of biodiversity is poor with only 5 per cent of the population aware of the term (Cuthbert, 2002) and few having an understanding of the relevance of biodiversity or of the methods of protection. There are several obstacles to progress including perceived time and cost constraints (Cuthbert, 2002).

Scotland has a high reputation for its academic and research skills in relation to biodiversity, with particular strengths in conservation biology, marine biology and in population and ecological genetics. However, concerns have been raised about a serious loss of taxonomic expertise, due to a failure to train new recruits into professional positions (House of Lords, 2002). There have been calls for more attention to taxonomy, and to create an inventory of Scotland's biodiversity.

Scotland has invested in preparing and storing species collections, for example at the National Museums of Scotland and the Royal Botanic Garden Edinburgh, and for examining live marine species (with laboratories at Millport, Oban, Orkney, Aberdeen and St. Andrews), and all of these offer excellent opportunities to investigate and conserve Scotland's biodiversity and to assist in biodiversity conservation worldwide. For example, analysis of wildcat ( Felis silvestris) specimens has helped in the development of techniques for distinguishing them from domestic cats and their hybrids, which is vital for the wildcat's effective legal protection. Specimen collections also offer the opportunity to extract DNA for taxonomic, population and genetic variability studies and there have been calls for the creation of a national DNA bank.

It has been estimated that there are over 8,000 jobs in activities related to the natural heritage. Approximately 60 per cent of these are in the public sector and 20 per cent each in the private and voluntary sectors (SNH, 2001). In addition, there is a wealth of voluntary effort marshalled by non-governmental organisations.

Statutory protection of conservation sites through designation of Sites of Special Scientific Interest, Special Areas of Conservation and Special Protection Areas, complemented by non-governmental initiatives, has created a network of protected sites across Scotland. Protection is provided for a long list of species. This approach has been criticised as being piecemeal and inflexible. The UK Biodiversity Action Plan and Local Biodiversity Action Plans are achieving a degree of co-ordinated action without additional specific funding.

1.6 Economic resource

Scotland's biodiversity can be valued in economic terms by various methods. The Costanza methodology (Costanza et al., 1997) estimates that the total environmental services provided by Scotland's land, waters and sea out to a 12-mile limit amount to around 15 billion per year, compared to a gross domestic product of 60 billion (SEPA, pers. comm.).

Attempts have also been made to assess the value of various landscape features to the public by determining how much each individual might be willing to pay to prevent the loss of a specific feature. It has been estimated that the scales range between 6 per hectare for heather moorland and 36 per hectare for hay meadows (Hanley et al., 2001). The natural heritage is also a key selling point for the majority of overseas tourists. For example, 74 per cent of Italian visitors say they associate nature and wildlife with a visit to Scotland (TEF, 2001). The chance to see species, perhaps common in Scotland but rare elsewhere, enhances the visitor experience.

Nearly 30,000 people are employed in wildlife tourism and there are 283 dedicated facilities and sites. Scotland's ospreys alone attract 1.7 million of business, while whale and dolphin watching generate 2.7 million and 0.7 million respectively (TEF, 2002). Angling on the River Tweed brings 12.5 million to the area (SERAD, 2000). Both fishing and shooting are highly dependent on Scotland's scenery and natural heritage. There is, therefore, no doubt that Scotland's biodiversity can be viewed not just as a scientific resource, but as a resource contributing both to Scotland's economy and to the environment in which its people live and work.

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