Land Cover

The NCMS provides information on land cover change throughout Scotland. ‘Land cover’ refers to features of land surface, which may be natural, semi-natural, managed or man-made. They are directly observable and in the case of NCMS remotely so from air photography. ‘Land use’, on the other hand, refers to activities such as agriculture, forestry or recreation. Not directly observable, inferences about land use can often be made from land cover. A reason for developing and maintaining a land cover monitoring study is to provide a consistent view of the stock and state of our natural and built resources as they change through time.

The terms ‘land cover’ and ‘land use’ are not synonymous. Land use denotes the human employment of the land, so that a change in land use at any location may involve a shift to a different type of use, say from farming to residential, or a change in the intensity of use. Land cover denotes the physical state of the land, such as the quantity and type of surface vegetation, water and earth materials.

The poster illustrates an imaginary landscape, but with recognisable elements of land utilisation extending from mountain to coast. The environment of towns and cities is now where most people in Scotland live, while advances in transport and communications have made once-remote parts of Scotland accessible for development and recreation.

The present day Scottish population of 5.1 million people lives predominantly in the Central Lowlands, although growth rates have become especially rapid in the hinterlands of Aberdeen and Inverness. According to the 1988 land cover census, 97 percent of Scotland’s land area is non-urban and about one tenth of the population lives in ‘rural’ areas.

Scotland’s land area is mainly rural, but its population is largely urban. It may be interesting to compare and contrast different areas through ‘twinning’ school projects.

To manage the complexity in Scottish landscapes, the NCMS simplified land cover by grouping features into 31 areal and 5 linear components [Table 3.1]. These are discussed below, based on summary results for Scotland [Table 5.1].

a) Grassland

Three-quarters of Scotland is classed as agricultural land, much of which is grassland. Grasslands can be differentiated in a number of ways ecologically, but grassland function and use were most relevant in the NCMS study. For instance, rough grazing is associated with relatively low stocking intensity and semi-natural vegetation in the uplands. Permanent pastures, predominantly in the lowlands, can be graded according to the degree of sward improvement. Under suitable management, including drainage, liming, fertiliser application and surface treatment, most pastures can be upgraded to better pasture quality in order to provide higher livestock output.

The NCMS classification relied upon air photographic characteristics of tone, texture and contrast. Three broad classes of grassland were differentiated as ‘rough’ (mainly uplands), ‘intermediate’ (partly improved) and ‘smooth’ (improved pasture). Transition from rough to smooth implied an increasing intensity of land management associated with grassland improvement.

grassland

1940s baseline

  • 30% of the area of Scotland was grassland
  • of the total grassland area about half was rough, a third smooth and the rest intermediate

1940s - 1980s change

  • 7% reduction in grassland extent overall
  • an increase in area of intermediate grassland (from pasture improvement) was offset by declines in the areas of rough (to afforestation) and smooth grassland (to arable and built land)

1980s outcome

  • 28% of Scotland was grassland

b) Mire

‘Mire’ is the generic term for a wetland which supports vegetation that is capable of peat-formation (through the incomplete decay and steady accumulation of dead material in a largely waterlogged environment). The two main forms of mire are ‘fens’, which form where water flow is impeded, and ‘bogs’ which are rainfed. With increasing altitude, latitude and oceanicity, summers remain cool and there is no seasonal moisture deficit. Where topography permits conditions become favourable for the development of a continuous mantle of peat, termed ‘blanket mire’ in which ‘blanket bog’ is the main constituent. In the lowlands, where a summer moisture deficit is more pronounced, topography and restricted drainage may be conducive to the much scarcer formation of ‘raised bog’.

‘Blanket mire’ and ‘lowland mire’ were mapped by NCMS, essentially corresponding to the two main types of bog. A marked gradient in the input of aerial nutrients arises from ions from the sea, to some extent mirroring the rainfall pattern from west to east. These combine to encourage a grassy vegetation in the west and heather cover towards the east. This distinction was recognised during the NCMS classification of blanket mire, which was sub-divided into ‘grass-dominated’ and ‘heather-dominated’.

mire

1940s baseline

  • almost 30% of the area of Scotland was mire
  • of the total mire area, 61% was heather-dominated blanket mire, 38% was grass-dominated blanket mire, and less than 0.5% was lowland mire

1940s - 1980s change

  • estimated 21% reduction in overall area (mainly due to afforestation and land drainage)
  • a suggested decline in grass-dominated blanket mire was less marked than the much greater reduction of heather-dominated blanket mire
  • relatively small in extent, lowland mire showed a marked reduction in area (mainly afforestation and drainage)

1980s outcome

  • less than a quarter of Scotland was mire
  • of the total mire area, 56% was heather-dominated blanket mire, 43% was grass-dominated blanket mire, and less than 0.5% was lowland mire

c) Heather Moorland

For much of the post-glacial period heathland has been a feature of north-west European landscapes. With few extensive areas of heather moorland left outside Great Britain, it is considered to be of considerable economic, nature conservation, landscape, aesthetic and tourism value. In Scotland, heather moorland occurs predominantly in the sub-montane zone between the former natural treeline and enclosed agricultural land, supporting a rich assemblage of moorland invertebrates, birds and mammals.

Apart from heaths at high altitudes and on exposed coastal areas, heathland plant species composition has been modified over thousands of years of land management, mainly by grazing and fire, to provide habitat for sheep, red grouse, and red deer. Semi-natural in character, heath is composed mainly of native species derived from former scrub and woodland cover. It is sustained by appropriate grazing and burning regimes, and may revert to scrub and woodland where the pressure of grazing and burning is insufficient, or be pushed towards grassland dominance where it is too intensive.

The NCMS classification for heather moorland was where dwarf shrubs exceed 25 percent of the ground cover.

heather moorland

1940s baseline

  • nearly a fifth of the area of Scotland was heather moorland
  • relatively most abundant in upland Regions of Grampian (29%), Tayside (24%), Shetland (22%) and Highland (21%)
  • least abundant in Fife (1%) and the Orkney Islands (8%)

1940s - 1980s change

  • 23% reduction in the area of heather moorland
  • greatest area reductions in Highland (19%), Grampian (35%) and Tayside (35%)
  • biggest reductions to afforestation and conversion to rough grassland
  • gains from the drainage of blanket mire

1980s outcome

  • 15% of the area of Scotland was heather moorland
  • most abundant in the Shetlands (26%), Grampian (19%) and Western Isles (18%)
  • least abundant in Fife (< 0.5%), Dumfries & Galloway (4%) and the Orkney Islands (6%)

d) Arable

Topography and climate limit intensive crop production in Scotland to the lighter, fertile soils in lower rainfall areas, mainly in the eastern lowlands.

Major trends in recent decades have been the intensification of farming, the increasing scale of farm operations and increasing specialisation. Mechanisation replaced labour-intensive farming systems. The introduction of selective herbicides replaced weed control measures of crop rotation and cultivation. A better understanding of agronomy (including seed dressing, fertiliser requirements, improved crop varieties, and the chemical control of pests and diseases) increased yields. Further gains arose from the breeding of more productive short-strawed cereals and crop varieties with pest and disease resistance. Mechanisation countered the vagaries of weather, and replaced labour with high-speed operations of sowing and harvesting. On-farm storage, dryers, chillers and conditioners, together with processing, marketing and transport, became integral to meeting ever more demanding standards7.

Without differentiating between crops, the NCMS classification of ‘arable’ land includes cereal crops, horticulture and cultivated land. Temporary grassland ‘leys’ are associated with arable farming as a break crop to help control pests and disease, and are included in the NCMS arable classification.

arable

1940s baseline

  • 10% of the area of Scotland was arable
  • relatively most abundant in the lowland Regions of Fife (46%), Lothian (34%) and the Orkney Islands (35%)

1940s - 1980s change

  • slight 1940s to 1970s reduction was reversed from 1970s to 1980s, resulting in a net area increase of 11%
  • biggest percentage gains in Dumfries & Galloway (118%), Tayside (30%) and Grampian (28%)
  • significant reduction in Lothian (14%)
  • biggest gain from smooth grassland
  • biggest reduction to urban development

1980s outcome

  • 11% of the area of Scotland was arable
  • still relatively most abundant in the lowland Regions of Fife (53%), Lothian (29%) and the Orkney Islands (25%). Least abundant in Highland and the Shetland Islands (both 1%)

e) Woodland

In an unaltered state Scotland would be mainly wooded, except on mires where the ground is too waterlogged for tree growth and on mountain tops and coastal margins where exposure imposes altitudinal and latitudinal limits. That Scotland today is mainly deforested is largely a legacy of land clearance for agriculture since Neolithic times, around 5000 years ago. The arrival of Celtic peoples around 2,500 years ago heralded the Iron Age, creating a demand for fuel timber and the technology for more extensive forest clearance. By medieval times, 1000 years ago, much of the country was denuded of trees.

By the outbreak of the First World War, only around 5 per cent of the land area was under tree cover and domestic timber production accounted for less than one-tenth of needs. The Forestry Commission was established in 1919 to create a strategic timber reserve and to reduce the nation’s dependence on imported timber. Inter-war plantings were still immature at the outbreak of the Second World War, which resulted again in heavy felling.

Speedy and large scale action was required to replace growing stocks and to increase the area under woodlands, and so the Forestry Act of 1945 gave renewed stimulus to private and public sector planting.

To avoid competition with agriculture, forest expansion was directed into marginal upland areas, with a view to diversification of employment and establishing a balance of land use between agriculture and forestry. Although infertile soils, difficult terrain and harsh climate were least satisfactory for tree growth, the sale of large estates helped to supply land for forestry. The development of the Cuthbertson plough in the 1930s allowed blanket peat to be ‘moor-gripped’, or drained, and the introduction of the ‘humpy’ plough in the 1960s enabled the ploughing of deeper peat areas.

The NCMS broadly reflects the classification of British forests according to continuity of forest cover on a site (ancient or secondary), whether the forests have ever been replanted (semi-natural or planted) and whether they are composed of predominantly broadleaf or conifer species.

woodland

1940s baseline

  • 5% of the area of Scotland was woodland
  • of the total woodland area nearly 60% was broadleaved, just over a third coniferous plantation and 6% (long-established) coniferous woodland

1940s - 1980s change

  • more than doubled in overall area
  • a seven-fold increase in coniferous plantation was partially offset by declines in the areas of broadleaved and coniferous woodland

1980s outcome

  • 14% of Scotland was woodland
  • of the total woodland area 84% coniferous plantation, 14% was broadleaved and 1% coniferous woodland

f) Fresh Water

Nine-tenths of the standing fresh water volume of Great Britain lies within Scotland. For their purity and attractiveness, the fresh waters of Scotland are renowned internationally for sport, recreation, tourism and nature conservation. In addition to their aesthetic value, fresh waters are essential to a modern society for the supply of drinking water, irrigation and energy, and as a medium for the disposal of wastes.

From the earliest times to the present day, Scotland’s fresh waters have been vital to meeting a range of domestic and industrial demands for water and power. While the availability of fresh water in Scotland far exceeds requirements, seasonal and regional differences in supply and demand mean that water needs to be stored in areas of surplus and piped to areas of deficit. Topography, geology and climate provide very favourable conditions for power generation, especially in the Highlands. The power available from water increased dramatically with the advent of hydro-electricity, and in the 20 years following the Second World War a range of schemes were constructed.

fresh waters

1940s baseline

  • comprised about 3% of the area of Scotland
  • about half of the fresh water area was lochs, a quarter wet ground with the remainder largely rivers and reservoirs

1940s - 1980s change

  • slight increase in area, mainly 1970s to 1980s
  • a reduction in loch area was related to reservoir development
  • ditches doubled in overall length, from around 50,000 km to 100,000 km, mainly associated with mire drainage

1980s outcome

  • about 3% of the total land area of Scotland
  • just under half was lochs, nearly 30% wet ground with the remainder largely rivers and reservoirs

g) Built and Bare Ground

Superimposed upon the landscape, the pattern of early towns and cities evolved in response to local circumstances. While the soils, vegetation, climate and hydrology of urban areas have been greatly modified, relics of landscape features and wildlife habitats may survive as rivers and streams, fragments of ancient woods, moors and wetlands. Vitally important to the quality of people’s lives for leisure, health and environmental education, green spaces within urban settings also include remnants of ancient natural systems, pre-industrial encapsulated rural landscapes, town parks and private gardens, and naturally-seeded urban or industrial sites8.

The NCMS classification of built and bare ground incorporates a range of features, associated with settlements, recreation, economic activity and transport, as well as naturally occurring scree and cliff.

built and bare ground

1940s baseline

  • covered about 3% of Scotland
  • about 41% was built-up, 31% transport corridor and 21% rock
  • over 29,000 km of tracks

1940s - 1980s change

  • increased in area by 37%
  • expansion of built-up areas (46%), transport corridor (22%), recreation (138%) and bare ground (418%)
  • tracks increased by 29% in overall length

1980s outcome

  • about 4% of the area of Scotland
  • 44% was built-up, 27% was transport corridor and 13% rock
  • over 37,000 km of tracks

h) Bracken and Scrub

In areas with a relatively mild climate, abundant rainfall and free-draining soils, bracken is a highly resilient invasive plant of rough grassland and heather moorland. The spread of bracken across upland pastures has been favoured where wet fields have been drained or where a change from cattle to sheep production has reduced trampling and grazing pressure.

Scrub vegetation was mapped by NCMS from the stage at which the area of woody plants exceeded that covered by grassland to when woody plants reach 5m in height. Grassland, scrub and woodland can interchange through time and nearly all unmanaged scrub communities will revert to woodland. A climax scrub community occurs only where severe exposure retards tree growth, such as beyond the northern and altitudinal limits for tree survival, or in rocky or exposed maritime areas. Through a long history of woodland clearance, burning and grazing, scrub in Scotland has become scarce and fragmented.

bracken and scrub

1940s baseline

  • 2% of the area of Scotland was bracken or scrub
  • of the total bracken and scrub area just over half was bracken

1940s - 1980s change

  • increased in overall area by 45%
  • bracken expanded by 80% and tall scrub by a quarter

1980s outcome

  • 3% of the area of Scotland was bracken or scrub
  • of the total bracken and scrub area nearly two-thirds was bracken

i) Hedgerows and Trees

Enclosure for the separation of crops and livestock was a distinctive aspect of agricultural change in the latter half of the eighteenth century and early years of the nineteenth. Enclosures were bounded by open ditches in low-lying areas and elsewhere by hedges, commonly using quick growing hawthorn. In many lowland areas walls were made of field stones thrown up by cultivation. Throughout the uplands, drystone dykes provided effective barriers and a means of using up large quantities of stones from the glacial tills.

Small-scale field systems proved to be incompatible with mechanisation, and hedgerows lost their function where arable specialisation replaced mixed farming systems. By occupying potentially productive land, hedges came to be viewed as an obstruction to agricultural efficiency. Hedgerow clearance in recent decades has stimulated concern for the broader value of hedges, in historical, landscape and wildlife terms.

The NCMS definition of hedgerow is of shrubs and trees less than four metres in height and five metres in width. It is classified as continuous if gaps are less than 10 metres wide. As remnants of former woodland or amenity planting, or as relics of unkempt, gappy hedges, lines of trees are also often encountered along field margins.

hedgerow and treeline

1940s baseline

  • total hedgerow length exceeded 42,000 km
  • highest density in Fife (2.3 km/km2) , Central and Lothian (both 1.6 km/km2)
  • over 17,000 km lines of trees

1940s - 1980s change

  • hedgerow length reduced by half
  • Fife, Grampian and Borders lost about two-thirds of their hedgerow

1980s outcome

  • under 20,000 km hedgerow
  • highest densities in Lothian (0.9 km/km2) and Fife (0.8 km/km2)
  • over 17,000 km lines of trees

CURRICULUM CONNECTIONS

The distinction between land cover mapping and land use mapping is an important, if somewhat neglected, one. Three times in this century – in the 1930's (Dudley Stamp), 1960's (Alice Coleman) and in the 1990's (Hex Walford) – schools have been involved in major surveys of the nation's land use. It would be more accurate however to describe these surveys as land cover surveys in rural areas and land utilisation surveys in urban and built environments.

Every geography department's work incorporates

  • analysis of rural land use data and crop yields in map, diagrammatic or tabular form,
  • analysis of farm survey results,
  • annotation and analysis of field sketches of rural and urban landscapes, and
  • analysis of urban landuse maps, transects and survey data e.g. pedestrian and traffic counts etc.

Let’s seize the opportunity to get the fun back into investigating land cover and land use, the central basis of geography as an integrating discipline.

  1. Carter, E.S. & Stansfield, J.M. (1994). British Farming: Changing Policies & Production Systems. Farming Press Books, Ipswich
  2. McCall, A. & Doar, N. (1997). The State of Scottish Greenspace. Scottish Natural Heritage Review No. 88. Scottish Natural Heritage, Battleby.