Information and Advisory Note Number 126
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NATURAL HERITAGE TRENDS Land Cover 1947-1988: enclosed
farmland
1. Arable
1.1 Arable cropping in Scotland is associated mainly with the tighter soils and
lower rainfall areas of the east. A thrust of the Agriculture Act 1947, and
subsequent measures, was to increase arable production. So successful were the
technological advances of subsequent decades that arable farming, the appearance
of the countryside and associated wildlife habitats were transformed.
1.2 Mechanisation countered the vagaries of weather, and replaced labour with
high-speed operations of sowing and harvesting. The introduction of selective
herbicides for weed control, the use of chemicals to combat pests and diseases,
and artificial fertilisers to enhance soil fertility, reduced reliance on crop
and livestock rotations. Plant breeding for short-straw cereals, and autumn sown
wheat and barley, boosted yields.
1.3 Three major land cover trends in recent decades have been an intensification
of farming, an increasing scale of operation as farms were amalgamated, and
increasing farm specialisation.
2. Trends
2.1 Entry into the European Economic Community in 1973 favoured arable
production, both in its own right and as livestock feed. Following a period of
little change between the 1940s and early 1970s, in the 15 years between c.1973
and c.1988, the area of arable land in Scotland is estimated to have increased
by 15%: a mean annual rate of 76 km˛.
2.2 Arable expansion (across 41 years between c.1947 and c.1988) was mainly
through the conversion of improved pasture.
2.3 Conversion of heather moorland to arable would typically have been preceded
by conversion to pasture and then, through further intensification, to arable.
2.4 The expansion of arable cropping was partly offset by urban growth.
2.5 The east of Scotland, most closely associated with arable farming, is where
arable expansion mainly took place. Land cover changes are consistent with a
replacement of mixed fanning systems with more specialised arable units.
2.6 In contrast, some contraction took place in parts of the west and northern
isles. In those areas which are associated with livestock rearing, the
geographical polarisation was reinforced as arable land was converted to
grassland.
2.7 The net trend was one of arable expansion. Overall, the arable area expanded
from around 7,700km˛ in the 1940's to 8,600km˛ in the 1980's.
3. Managed Grassland
3.1 Grasslands that have been modified by land management, agrochemicals and
re-seeding contain a limited number of plant species and relatively few animals.
The definition here, however, is not a botanical one but is based on the
appearance of grassland types interpreted from air photography. Grasslands that
are of 'smooth' or 'intermediate' appearance contrast with the more semi-natural
character of 'rough' grassland in that they are generally enclosed and more
homogeneous.
3.2 The extent of smooth (accounting for two-thirds) and intermediate grassland
(one-third) in the late 1980s was about the same as that of rough grassland. It
was geographically distinct: influenced by topography, soil and climate, the
distribution of lowland grassland and cattle (which are reliant on summer
grazing and hay or silage with other winter feeds) are correlated.
4. Trends
4.1 Between the late 1940s and the early 1970s, both smooth and intermediate
grassland expanded slightly. Whilst intermediate grassland continued to increase
into the late 1980s, the area of smooth grassland contracted more markedly.
4.2 Overall, the area of managed (intermediate and smooth) grassland increased
by 8% from the 1940s to the 1970s, but fell back to around its 1940s extent by
the late 1980s.
4.3 Two distinct changes took place between the 1940s and the 1980s:
• the intermediate area expanded by 15%, and
• the smooth area contracted by 11%.
4.4 Two equally distinct processes drove the changes in managed grassland.
4.4.1 Expansion of intermediate grassland:
Pasture improvement extended into marginal
areas (geographically peripheral and in terms
of restricted land capability). Rough
grassland, heather moorland and the fringes of
blanket mire were brought into more intensive
use for grazing. These 'gains' (mainly for
intermediate grassland and reflected in the
upper part of the chart shown below) were
partly offset by
• further pasture improvement, from intermediate to smooth grassland (not
visible in a combined chart), and
• forest planting (seen in the lower part of the chart).
4.4.2 Contraction of smooth grassland:
Smooth grassland expanded in similar ways,
but 'gains' were out-weighed by 'losses', due
mainly to
• conversion to arable, and
• urban development.
4.5 Intensification and specialisation brought about an expansion of managed
grassland in the west and outer isles.
4.6 In the east and south, managed grassland contracted through conversion to
arable. A degree of geographical polarisation became apparent. The arable east
became more arable, the pastoral west became less arable.
4.7 In other, and especially the more marginal areas, managed grassland also
contracted through forest planting.
5. Hedgerow
5.1 Many of Scotland's agricultural hedgerows originate from enclosure in the
latter half of the eighteenth century and early
years of the nineteenth. At that time, agricultural improvement required the
amalgamation of fragmented and intermixed strips and blocks of land, and the
segregation of crops and livestock. Hedgerows, as well as ditches and walls,
defined small-scale field systems and estate boundaries. Incompatible with
mechanisation, hedges subsequently became an obstacle to further agricultural
progress.
5.2 Their rapid decline stimulated concern for the broader value of hedges, in
historical, landscape and wildlife terms. According to their structure and
diversity, hedges can be important for food and shelter to invertebrates, birds,
mammals, amphibians and reptiles. Hedges can serve as woodland edges, and may
contain an abundance of fruit-bearing woodland-edge shrubs. Common woodland
birds can become dependent on hedges for song-posts, and as structures in which
to feed, roost, hide and nest.
6. Trends
6.1 Over 41 years, between c.1947, c.1973 and c.1988, the total length of
hedgerows in Scotland is estimated to have declined by 54%; a mean annual rate
of 560 km.
6.2 Reduction took place wherever hedgerows occurred. This was particularly so
in the more intensively farmed lowlands where there was evidence of
intensification, specialisation and a polarisation of arable and pastoral
farming systems.
6.3 The extent of hedgerows contracted from around 42,600 km in the 1940s to
19,500 km in the 1980s.
7. Source
7.1 Statistical estimates are from the 'National Countryside Monitoring Scheme',
a sample survey which interpreted air-photography representing 7.5% of Scotland's land area (Mackey et a/., 1998),
Although sampling is not optimal for this purpose, change in extent is mapped
here according to the 21 Natural Heritage Zones.
7.2 The geographical distribution of habitats was mapped using the nearest
equivalent features from the Land Cover of Scotland 1988 dataset (MLURI, 1993).
8. References
Macaulay Land Use Research Institute (1993).
The Land Cover of Scotland 1998:
Final Report. Aberdeen: MLURI.
Mackey, E.C., Shewry, M.C. and Tudor, G.J. (1998).
Land Cover Change: Scotland
from the 1940s to the 1980s. Edinburgh: The Stationery Office.
9. Further Information
Further information on other topics covered by Natural Heritage Trends: Land
Cover 1947-1988 can be found in Information & Advisory Note No. 123.
10. Contact
To obtain further information about any of the issues raised in this l&A Note,
please contact
Mr Ed Mackey and Mr Mike Shewry
Environmental Audit Group
Chief Scientist's Unit
Scottish Natural Heritage
2 Anderson Place
Edinburgh
EH6 5NP
Tel: 0131-446 2415
Fax: 0131-446 2405
E-mail: ed.mackey@snh.gov.uk
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