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18
Restoring Derelict Lands
in Great Britain
Reclamation of derelict lands is of increasing importance for industrial-
ized societies, both because quantities of lands so affected are increasing
and because the value attached to restoring natural vegetation on these
lands is increasing. Early reclamation attempts tried to produce vegetation
that looked pleasing and that reduced soil erosion. More recently, society
has demanded the creation or restoration of more complex natural com-
munities of plants and animals, even though this goal is more difficult
and expensive. The task requires knowledge of the tolerances of plants
for the environmental conditions; of the ways in which plants compete
with one another for access to water, light, and mineral resources; and of
the course of succession of plant species after establishment of pioneering
vegetation. Less attention has been paid to restoration of animal com-
munities, in part because animals often invade these sites naturally once
suitable vegetation has been established, and in part because less is known
about members of animal communities and how to manipulate them.
The Longstone Edge reclamation project in Derbyshire, England, rep-
resents the current state of the art of land reclamation. The project drew
on existing ecological knowledge about plant competition and succession,
but also included experiments to help develop new theories more applicable
to the specific conditions of reclamation with which the investigators had
to work. A particular part of the challenge one that is generally a com-
ponent of such projects was to produce vegetation that would be self-
regenerating once established, so that costly maintenance would not need
to be continued for long periods. In Britain, most derelict sites are on
248
.
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RESTORING DERELICT LANDS IN GREAT BRITAIN
249
very poor soils; the specifics of the Longstone Edge results are, accord-
ingly, applicable to many other sites in that country. In North America,
however, many sites being restored are on richer soils, and techniques
adapted to those conditions, as well as to the more continental climates
prevailing in most of North America, will need to be developed to meet
challenges there.
Case Study
PETER WATHERN, Department of Botany and Microbiology,
University College of Wales, Aberystwyth
INTRODUCTION
Bradshaw and Chadwick (1980) estimated the amount of derelict land
in the United Kingdom in April 1971 at over 55,000 hectares (ha), and
the consensus is that the amount has increased steadily in recent years.
Much of this dereliction is the result of mining activities, and pressures
on resources in the United Kingdom are such that mineral deposits are
likely to be worked with little or no concern for their location. Thus,
mining operations often occur in some of the most scenically attractive
and environmentally sensitive areas, such as national parks. Examples
include Dartmoor (kaolin), Yorkshire Dales (heavy metals and fluorspar),
and the Peak District (heavy metals, fluorspar, and limestone). Many
areas, including western and northeastern Wales and Cornwall, carry a
legacy of dereliction from mines long defunct.
In the United Kingdom, reclamation of despoiled land has been a fertile
area for research for more than 2 decades, since the pioneering work in
the Lower Swansea Valley of Wales reported by Hilton (19671. Recla-
mation research has been geared to developing techniques for achieving
three main objectives: to restore land so that it can be used productively,
to remove local sources of environmental pollution associated with toxic
materials in discarded wastes, and to make a site visually attractive again.
Reclamation has generally been achieved by establishing a vegetation
cover that prevents further weathering and allows such productive uses as
agriculture, forestry, housing, manufacturing, and recreation. Thus, rein-
statement can be regarded as an essential component of the recycling of
land through a succession of uses.
In some instances, derelict land detracts markedly from an otherwise
pleasing landscape and must be reclaimed in the interests of visual amenity,
irrespective of a readily apparent productive after-use. The major concern
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250
SELECTED CASE STUDIES
in the reinstatement of such sites is the creation of an area that, at worst,
blends with the surrounding landscape or, preferably, is pleasing in its
own right. This case study describes experimental work undertaken to
develop techniques for dealing with such situations.
Longstone Edge, Derbyshire, is a limestone scarp situated in a prom-
inent position in the heart of the Peak District National Park. It visually
dominates an area intensively used for recreation. Fluorspar deposits are
found in a vertical vein (locally known as a rake) running for about 1.5
km along its crest. The deposits are worked by a combination of open-
cast and deep mining techniques. The area has a long history of lead
mining, and the steep scarp face of Longstone Edge is covered with waste
heaps tipped to a depth of some 5 m by medieval miners. These waste
heaps of gangue minerals, such as fluorspar and barytes, are being re-
worked by the mining company. Much of the site, including the medieval
waste heaps, is covered with species-rich calcareous grassland, and heath
dominated by heather (Calluna vulgaris) has developed on superficial
loessic drift (Balme, 1953; Pigott, 19621. The limestone grassland contains
several rare species, including Epipactis atrorubens, Minuartia verna,
Orchis apifera, and the terricolous lichen Cetraria islandica. As a result
of mining activities, seminatural vegetation is being destroyed over much
of the site.
The general objective of the experimental work described here was to
learn whether it would be possible to recreate the seminatural grasslands
being destroyed by mining operations. The experimental areas were flat
plots beside the worked-out rake. In addition, plots were established on
the steep south-facing slopes of the Edge itself. The mining company had
attempted reinstatement of some areas that provided a valuable contrast
with the experimental plots. The experiments were set up in February-
September 1972 and covered about 2 ha. The experiments are continuing,
in an attempt to establish the long-term fate of the sown vegetation the
only real criterion of success in reinstatement.
ENVIRONMENTAL PROBLEMS IN REINSTATEMENT
Derelict land reclamation has been the subject of intensive research in
the United Kingdom so long that few waste materials or mine sites present
insurmountable problems for reinstatement. The existence of large amounts
of derelict land reflects the limited resources that have been made available
for such work, rather than a lack of appropriate techniques. As a result
of the work mainly of A. D. Bradshaw and his co-workers at Liverpool
University since the early 1960s, even seemingly intractable wastes con-
taminated by toxic substances can be revegetated with ecotypes able to
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RESTORING DERELICT LANDS IN GREAT BRITAIN
251
tolerate the presence of these materials. Toxic metals present such a special
problem that there is probably no alternative to the use of this approach.
However, the treatment of nontoxic wastes has been much debated. The
primary consideration has been to develop a recipe that can be used to
produce a quick green cover, irrespective of its appropriateness as a long-
term solution. This search for universal recipes that eliminate, rather than
accommodate, constraints on vegetation development has colored much
of the research on derelict land reclamation. The major constraints on
plant growth on derelict land, apart from possible toxic effects, are low
nutrient status, low soil organic content, drought stress, and, if the material
has been mechanically sorted, uniform particle size.
Abandoned mineral workings and waste materials such as alkali wastes
(Lee and Greenwood, 1976), quarries (Davies, 1976; Hodgson, 1982),
and wastes contaminated with heavy metals (Holliday and Johnson, 1979;
Johnson, 1978; Johnson et al., 1978) often develop into important pre-
serves for seminatural vegetation. The evidence suggests that there is no
need to reclaim derelict or abandoned mineral workings, because an in-
teresting vegetation will develop naturally, given sufficient time. But that
stance neglects important changes that have rendered old sites unreliable
as models. The changes affect all three main phases of the diversification
of sown vegetation (Wathern, 19771:
· Transfer. Propagules of the species must be dispersed from an es-
tablished stand and arrive at the reinstated site.
· Establishment. Propagules must become established and develop into
mature plants.
· Periodic recruitment. From time to time, new individuals derived
from the original source or from the new population must become estab-
lished, and the rate of recruitment should at least equal the death rate, if
the population is to be sustained.
The abandoned mineral workings that are now biologically so interesting
began their development in the early decades of this century. The landscape
over much of the United Kingdom was different from that seen today.
Seminatural vegetation was the basis of much of the land use. Wood
products were derived largely from broad-leaved woodlands, rather than
softwood plantations. Pastoral agriculture relied on the use of seminatural
grassland for grazing and hay. Thus, the countryside had a basic matrix
of seminatural vegetation that could serve as a source of propagules for
the diversification of abandoned mine workings. Transfer distances were
short and within the capabilities of most species. The preponderance of
wind-dispersed species on the alkali wastes highlighted by Lee and Green-
wood (1976) indicates the importance of isolation, in that these waste
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252
SELECTED CASE STUDIES
areas are many miles from potential seed sources. Species with other types
of dispersal mechanism usually move only a short distance with each
generation and can move long distances only incrementally through a
chain of suitable habitats. At present, however, species are becoming
concentrated in fewer and fewer refuges. It is likely, therefore, that a
quarry site abandoned today will be many miles from potential sources
of propagules and that transfer distances will be too great for many species.
In addition, because mining and quarry operations have changed over
the years, it is unlikely that modern sites will acquire the same ecological
interest as the old sites. Large-scale workings are preferred, and mineral
extraction produces uniform conditions over extensive areas. A modern
limestone quarry lacks the physical diversity of an old quarry with its
uneven face, rubble-strewn floor, and scattered waste heaps, which ac-
count for much of the biological interest. Such diversity can be created
only by a program of treatment after quarrying operations have ceased.
Many of the old skills have been lost, but Humphries (1977) describes
how, for example, a quarry face could be treated.
The final objection to a laissez-faire attitude to site rehabilitation is not
biological. Society will no longer tolerate the visual intrusion of a derelict
mineral working or quarry over a long period in the hope that interesting
habitats will eventually develop. Industry must be seen to be rehabilitating
environments degraded by its activities. The challenge in derelict land
reclamation is to reinstate a site so that its visual impact is reduced, while
maintaining its potential for development into a biologically interesting
area.
The traditional approach to reclamation of derelict land for visual amen-
ity has been based on agricultural techniques. In the period 1967-1972,
the mining company made considerable efforts to revegetate areas on
Longstone Edge where extraction was complete or where there was a
temporary halt in operations. The approach adopted was to sow agricultural
seed mixtures (Lolium perenne, Dactylis glomerata, and Phleum berto-
lonii) on raw subsoils with heavy fertilizer applications. It soon became
apparent that this agricultural approach would provide no long-term so-
lution. Whenever such grass-seed mixtures were sown, a green cover
developed briefly. After a short period of vigorous growth, swards became
moribund, the grasses showed signs of nutrient deficiency, and standing
crops declined. On these free-draining soils lacking organic matter, nu-
trients, particularly nitrogen, were leached out. Periodic applications of
fertilizers became the main form of management used by the mining
company. Clearly, there would be considerable advantages in developing
some form of single-application treatment that would lead to stable veg-
etation. It would be more visually acceptable to the public and to the
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RESTORING DERELICT LANDS IN GREAT BRITAIN
253
controlling authority, the Peak Park Planning Board, and it would have
obvious economic benefit.
Either of two approaches could be adopted: constraints on the produc-
tivity of high-yield species could be eliminated, or constraints on the
system could be accommodated by creating some form of low-productivity
system whose demands for nutrients would be better attuned to the ability
of the system to supply them. The first approach has been used successfully
in the revegetation of kaolin wastes in Cornwall. Kaolin wastes are nu-
trient-deficient, drought-stressed environments (Bradshaw et al., 1978),
and fertilizers must be added regularly to maintain vegetation cover (Brad-
shaw et al., 19751. To overcome this problem, a biological source of
nitrogen was sought. Rhizosphere fixation was inadequate to achieve the
target of about 700 kg/ha estimated by Bradshaw et al. (1975) to be
necessary to produce a self-sustaining system. The potential of nitrogen
fixation by nodule bacteria in legumes was investigated in a series of trials.
The results showed the use of legumes to be a means of overcoming
nutrient limitations (Jefferies et al., 19811; Lupinus arborous, the tree
lupine, was the most effective species (Palaniappan et al., 1979), but is
not native to the United Kingdom. Although sowing legumes is useful for
reinstating some nutrient-deficient substrates, it was rejected for Longstone
Edge, because the seminatural vegetation of Longstone Edge comprises
calcareous grassland and Calluna heath, both of which are naturally nu-
trient-deficient systems. A productive agricultural sward created on the
mineral working would be out of context with the surrounding vegetation.
Consequently, it was decided to attempt to produce a low-productivity
vegetation in harmony with the existing nutrient-deficient system. The
potential of these swards appeared great. Grime (1973a) has argued that
environments moderately stressed by drought, nutrient deficiency, or graz-
ing support diverse communities. In contrast, high-productivity systems
are often species-poor. These low-productivity grasslands could be ex-
pected to develop into diverse swards akin to the existing seminatural
vegetation.
Local populations of plants could not be used as the sole source of
propagules in this research, because of the difficulty of interpreting the
experimental results. Because the natural arrival of propagules, mainly
seeds, in the experimental plots would be a chance occurrence, it would
be impossible to determine whether the failure of a particular species to
invade an area resulted from a lack of propagules or from an inability to
establish under the prevailing conditions. The ability of a sward to ac-
commodate a new species is termed its receptivity (Wathern, 19761. Nat-
ural seed rain provides a flow of only a small irregular number of propagules
into experimental areas; that makes it difficult to measure the receptivity
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254
SELECTED CASE STUDIES
of contrasted swards. Therefore, we diversified the swards artificially by
introducing known quantities of seeds of a range of native species, hoping
to create a visually pleasing community rapidly.
The decision to introduce native species deliberately raised an important
issue, which has since achieved greater prominence. Deliberate introduc-
tions are discouraged by scientists, mainly because they disrupt natural
distribution patterns, particularly of local ecotypes. However, because
plant distribution in the United Kingdom has been modified drastically
by human activity over a long period, that objection has little validity. In
these experiments, only commonly occurring species were used, and they
were collected from local seed sources whenever possible. This is an
ethical consideration that requires more thorough discussion, because fail-
ure to transfer species artificially might doom them to local extinction.
The ethics of introductions in the construction of natural ecosystems are
discussed by van der Hock (1982~.
APPROACHES TO RECREATING SEMINATURAL GRASSLAND
Experiments were established to investigate whether the yield of species
on the Longstone Edge subsoils was related to relative growth rate (RGR).
Monocultures of Lolium perenne (RGR~`, 1.30), Festuca rubra (1.18),
and F. ovina (1.00) showed an inverse relationship between yield and
RGRmaX after 3 years. Thus, the species with the greatest potential for
growth, L. perenne, performed least well. Other trial areas were sown
with two contrasting mixtures one consisting of F. ovina and F. rubra
and the other consisting of L. perenne, Dactylis glomerata (1.31), and
Poa trivialis (1.40) and monitored for 5 years.
After 1 year, the Lolium sward had almost twice the standing crop of
the Festuca sward. After 2 years, both grasslands had increased in yield,
but they did not differ significantly from one another. After 5 years, the
Lolium sward had the same standing crop as it had after 2 years; in the
intervening 3 years, it had become moribund. In contrast, the Festuca
sward continued to increase its standing crop throughout the experiment.
The results of this experiment, described more fully by Wathern and
Gilbert (1979), confirmed that nutrient-deficient subsoils could be rein-
stated successfully with low-RGR grasses.
Grasses, however, provide only the general matrix of the community
in seminatural grasslands. In the United Kingdom, many of the distinctive
elements, and certainly the visually dominant species, are dicotyledons.
Indeed, the seminatural grasslands of the carboniferous limestone are
renowned for their floral richness. Consequently, in parallel with the trials
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RESTORING DERELICT LANDS IN GREAT BRITAIN
255
on low-productivity swards, the feasibility of recreating seminatural grass-
lands was investigated. Experiments were established as long-term trials
in September 1972 and still cannot be considered complete. For the first
5 years, the plots were monitored fairly intensively, but they have since
been assessed only infrequently.
One area of Longstone Edge provided an opportunity to investigate the
effect of a grass seed mixture on the rate of invasion by native species
under natural conditions. Three years before experiments on Longstone
Edge began, the company had regraded a large area. Half this area had
been sown with a grass seed mixture, and the remainder had been inex-
plicably left fallow. The vegetation of the two sections was surveyed, but
no important differences in the number of adventive species could be
found. Initial seeding with a mixture producing an open sward did not
appear to affect the rate of diversification. This suggested that the two-
part objective of reinstatement reducing visual impact without signifi-
cantly affecting sward receptivity could be achieved. The second major
conclusion from this work was that, although diversification occurred
naturally, most of the adventives were species that produced large numbers
of highly dispersable seeds. It appeared that, without deliberate introduc-
tion, the more characteristic species of climax limestone grasslands with
larger, less readily dispersed seeds might not become established in the
short term.
In the light of these observations, experiments were set up to establish
the most appropriate means of diversifying swards and to determine the
receptivity of contrasted swards to native species. The Festuca- and Lol-
ium-based mixtures used in the low-productivity sward experiment de-
scribed above were used. Various sources of propagules of native species
were investigated. Hand-collected seed was broadcast at known rates in
the swards and fallow areas. After 2 years the Festuca sward contained
22 sown species; six species showed an establishment rate of over 10%.
The Lolium and fallow areas contained 15 and 17 species, respectively,
at low frequency. After 5 years, although the frequency of native species
had increased in all areas as a result of additional recruitment, self-set
seed, and vegetative spread, the differences among the Festuca, Lolium,
and fallow plots were even more marked than they had been after 2 years.
Thus, not only was the Festuca sward initially more receptive to native
dicotyledons, but this increased receptivity was sustained over a long
period. Adventive species also showed higher frequencies in Festuca areas
and after 12 years included important elements of the limestone grassland
flora.
In a separate experiment, sowings along a soil depth gradient showed
that sward performance determined establishment rates for native species.
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SELECTED CASE STUDIES
Establishment was greatest in swards of intermediate density. In such
swards, competition is not severe, but there are enough plants to ameliorate
the microclimate of developing seedlings. Dense swards eliminate native
species by competitive exclusion, whereas failure rates of seedlings in
open situations are high because of harsh environmental conditions (Wath-
ern and Gilbert, 19781. These experiments suggest that low-productivity
swards increase the rate of diversification by native species and that sowing
seed of native species by hand can create visually pleasing grasslands
rapidly.
Other sources of native species were investigated. From casual obser-
vations on the site, it was noted that fragments of old turf had become
established, particularly in compacted bulldozer tracks, providing small
islands of seminatural grassland. Therefore, turf stripped from an area
about to be reworked by the mining company was used in the diversifi-
cation trials with an oversewing of the Festuca mixture (Gilbert and
Wathern, 19801. The use of seed-rich topsoil on this site was not suc-
cessful, but the approach should not be dismissed, inasmuch as it has been
successful in other experimental areas. Seed-rich Calluna litter (Gim-
ingham, 1960) has been used to produce a Calluna heath community on
an acidic subsoil road verge on highway A57 west of Sheffield (Gilbert
and Wathern, 1976~. Similarly, Farmer et al. (1982) and Tacey and Glos-
sop ( 1980) have since used seed-rich topsoils for the reinstatement of mine
areas.
To obtain additional information on the fate of man-made swards, a
chronosequence of grasslands up to 150 years old was analyzed. A sample
of 69 quadrats covering the complete range of grassland age was recorded.
Soils were taken for laboratory analysis to determine whether edaphic
factors were controlling the composition of the vegetation. For grasslands
less than 25 years old, specifications for the original seed mixtures were
known. The detailed procedures, particularly the seed mixtures, used to
create the older grasslands could not be discovered. The major finding of
this study was that soil nutrient status was the most important factor in
controlling succession in urban grasslands (Wathern, 1976, 19801.
USES OF KNOWLEDGE
Of the ecosystem modifications listed by Wathern (1984), the most
important changes resulting from development that influence reinstatement
appear to be simplification, the opening of previously closed nutrient
cycles, and the loss of vegetation types. The objective of revegetation
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RESTORING DERELICT LANDS IN GREAT BRITAIN
257
should be to redress that progression. Many of the objections to devel-
opment are based on amenity, so it seems appropriate for reinstatement
to aim at creating vegetation that has or can rapidly acquire amenity value.
The application of agricultural technology to this problem, however, has
often failed to achieve this objective. In the case reported here, ecological
knowledge was used to develop a more subtle approach to reinstatement.
The revegetation of mineral workings on Longstone Edge was designed
to satisfy five criteria: reinstated swards should be inexpensive to produce,
result from a single simple treatment, require no intensive management,
be visually pleasing, and resemble surrounding seminatural vegetation.
The research involved field observations and theoretical considerations
aimed at understanding the relationships between reinstated grasslands and
the environment and then application of this information in devising a
reclamation scheme. The application of ecological considerations pervaded
the study. However, ecological knowledge figured most prominently in
four ways: production of low-productivity swards, sward diversification,
assessment of the potential of soil seed banks, and urban grassland succes-
sion.
Low-Product~vity Swards
The most important concept used in this phase of the work involved
the ecological importance of relative growth rate. Hunt (1970) and Grime
and Hunt (1975) measured the RGR of 115 species in a uniform high-
nutrient environment. The RGRma,, of each species was determined. This
study showed that low-productivity environments are characterized by
species with low RGRma,~, whereas productive systems contain species
with high RGRmax.
The agricultural species used previously in landscape reinstatement have
high RGRm~. When sown on Longstone Edge, they initially produced a
green cover, because artificial fertilizers provided the high concentrations
of nutrients required for their growth. These skeletal soils, however, have
a low organic content. Under these conditions, nutrients are not held within
the system, but rapidly leach out. For the highly productive species to
flourish, fertilizers must be added regularly. From Hunt's observations,
it can be predicted that such soils would naturally carry species with low
RGR. If those species were sown during reinstatement, the results should
be more satisfactory than those obtained with agricultural species. Thus,
the work on RGR provides the theoretical basis of the reinstatement of
low-productivity swards. In turn, the experiments provide a field trial of
the importance of growth rate in explaining plant distribution.
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2S8
SELECTED CASE STUDIES
Sward Diversification
High RGR, which reflects the ability of a species to use resources that
are freely available, is only one of the characteristics by which one plant
can gain a competitive advantage over another. Structure and height affect
competition for light, and the ability to produce litter that persists from
one growing season to the next is an aid to occupying space when a plant
is not actively growing.
Grime (1973a) argued that these four attributes can be amalgamated
into an index of competitive ability. Species with high competitive index
("competitors" in Grime's terminology) grow in productive environments
where resources, such as nutrients and water, are freely available. Such
environments are species-poor, because competitors eliminate other spe-
cies that are less able to exploit the resources. Environments where re-
sources or physical and chemical constraints severely limit plant production,
described as "stressed," are also species-poor. Only a few species are
adapted to tolerate extreme conditions of, for example, drought or heavy-
metal contamination. Such species are characterized by very low RGRm~,.
Composition of a particular community, however, is dictated not only
by the growth rates of the constituent species and by the physical and
chemical characteristics that can limit the full realization of this potential.
The degree of disturbance of the environment, such as grazing, is a third
factor. Poverty of species is associated with a high incidence of distur
bance.
Grime advocated a triangular ordination as the means of analyzing
community composition, the axes being the relative importance of com-
petition, stress, and disturbance. At the extremes, species-poor commu-
nities are present. Diverse communities are found where competition,
stress, and disturbance are all moderate, and they are characterized by
species that exhibit the "C-S-R" strategy in Grime's terminology. C, S.
and ~ stand for competitive, stress-resistant, and ruderal (weedy). Such
plants are "confined to habitats in which competition is restricted to
moderate intensities by the combined effects of stress and disturb-
ance . . ." (Grimes 19771. The Longstone Edge reinstatement areas have
this combination of features, so they should ultimately develop into rich
communities of C-S-R fortes. The major representatives of C-S-R strategies
in the U.K. flora are small tussock grasses, small deep-rooted fortes, small
stoloniferous species, fortes with short rhizomes, legumes, and small sedges
and rushes (Grime, 19791.
The major grasses used successfully to form the low-productivity sward
on Longstone Edge were two small tussock-formers, Festuca ovina and
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SELECTED CASE STUDIES
species occurs. This atlas has been described as a practical aid for land-
scape managers involved in, for example, revegetation, but that appears
to be a post hoc rationalization of its function. Selection of species for
landscape reinstatement is determined by pragmatic considerations, such
as seed availability, ease of establishment, and likelihood of success. These
considerations are not addressed in the atlas. For example, productivity
of the systems in which a species occurs, acknowledged elsewhere by
Grime as a major factor in determining distribution, is not considered.
The atlas therefore has the wrong emphasis to be valuable in revegetation.
Consequently, the information on distribution was not used in the re-
vegetation trials. Species from a wide range of habitats were selected for
the diversification experiments. It was felt that this approach would be
better, because it would provide information on the conditions necessary
not only for success, but also for failure.
Ecological Theory
The results of the seral study on urban grasslands and the subsequent
diversification trials illustrate well the implications of the theory of plant
strategies and community ecology for reinstatement studies. There were
important changes in the status of this theoretical background over the
course of the work described here. At the outset, the theory was still being
developed by Grime in Sheffield. It was not published until most of the
experiments had been set up, although the general tenor of the ideas was
known. Thus, during formulation of the reinstatement work, the urban-
grassland study and papers on the relationship between diversity and nu-
trient status were more important.
Preliminary analysis of the experimental work began in 1974, after
publication of the basic theoretical concepts (Grime, 1973a,b, 19741. The
theory has been further developed by Grime (1977, 1979), but not all
aspects have been accepted without dissent (see, for example, Newman,
19734. With this more comprehensive theoretical base, the results of the
experimental work became more important and could be set within a
broader context. The results demonstrate that diverse vegetation can be
created artificially under conditions of moderate stress, as the theory pre-
dicts, and that the techniques used constitute a worthy strategy for rein-
statement of disturbed land for visual amenity.
Analog Studies
No reports of previous attempts to reinstate mineral workings to semi-
natural vegetation were discovered during a systematic search. Work on
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RESTORING DERELICT LANDS IN GREAT BRITAIN
265
diversification of road verges, however, is relevant to the study. Additional
diversification trials were established on road verges in the Sheffield area,
because they have the potential to make a major contribution to the reserves
of seminatural habitats in the United Kingdom (Mellanby, 19741. The
results were reported by Wathern and Gilbert (19781. A number of previous
attempts at establishing native species in verges have been reported in the
conservation press, and these were investigated in detail.
Most cases were in the form of "rescue" operations, in which popu-
lations of rare species were threatened by highway construction. Generally,
mature plants were returned to the verge after a period in a nursery to
bridge the construction phase. The most spectacular success has been the
mass planting of native Narcissus pseudonarcissus (daffodil) on the M40.
There were a few attempts at more general diversification. Calluna turf
was used successfully for reinstatement at the Devil's Punch Bowl, Surrey,
after roadwork and at Cumbernaud New Town. Commercially available
herbs have been used on road verges in southeastern England. The results
of this work have never been published. Significantly, some members of
voluntary organizations had suggested more general diversification of
highway verges in their areas, but such proposals were invariably aban-
doned after objections on the grounds that distribution patterns would be
disrupted. The main value of the analog studies was in confirming that
artificial diversification could be achieved. In general, the labor-intensive
approaches were rejected as being inappropriate for large-scale projects.
Experimental work in the Netherlands on landscape reinstatement was
of particular interest, but it was not seen until the Longstone Edge trials
had been established. The Dutch experience was useful in interpretation
of the experimental results, because a similar approach had been adopted
independently in many instances. For example, the problem of low-pro-
ductivity swards on sandy soils was investigated early (Hoogerkamp,
1971), and trials on the establishment of Calluna on highway verges had
shown the importance of a nurse crop in seedling establishment, as was
found in the United Kingdom (Gilbert and Wathern, 19761.
Expert Judgment
It should be clear from this discussion that a university provides a unique
atmosphere for research. The interplay of personnel leads to a rapid evo-
lution of ideas. The Longstone Edge study was undertaken in the De-
partment of Landscape Architecture of Sheffield University as a doctoral
research project. The supervisor was an experienced ecologist, and the
research student a botany graduate. There were also important links with
the Botany Department, in particular its Unit of Comparative Ecology.
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These contacts occurred during a formative and productive period for the
Unit, when ideas concerning plant strategies and community ecology were
being developed. The work on the comparative ecology of individual
species and the composition of plant communities might seem esoteric,
but the revegetation work on Longstone Edge has shown its relevance to
reinstatement. Although not published, information was freely available
to the study, and informal discussions around this work were useful in
the development of ideas concerning reinstatement.
Consultations with other organizations were not generally important in
the evolution of the work. However, discussions with experts outside the
university system, particularly government scientists in the Institute of
Terrestrial Ecology (ITE) and the Nature Conservancy Council (NCC),
took place. In addition, a British Council travel fellowship enabled the
work undertaken in the Netherlands to be discussed with government
scientists at IBS Wageningen in 1974.
The responses of research scientists differed. Most research workers
were concerned primarily with investigating the effects of management
on grassland composition. A few research scientists at ITE, however,
were also interested in creating seminatural grassland; indeed, they set up
experimental work in 1973 and 1978 (Wells, 19831. A guidance manual
on diversification has also been prepared (Wells et al., 19811. The dis-
cussions in 1971 generally concerned the need to develop techniques,
rather than how this might be done.
Sowings of wildflower species became quite common in the Netherlands
at one time (Cole and Keen, 19761. During the discussions with Dutch
scientists, however, the ethics of the approach were called into question.
This hinged not on theoretical considerations of disrupted distributions of
different ecotypes, but on a more fundamental point: whether people
should interfere in the development of an ecosystem.
The attitude of conservation officers in the United Kingdom was de-
fensive and antagonistic. Many saw within the techniques a potential
diminution in their ability to object to development proposals on conser-
vation grounds, because they believed that any suggestion that plant com-
munities could be recreated after development would undermine their
position. This attitude reflected a failure to understand the concepts un-
derlying the techniques. There is no suggestion of constructing commu-
nities that contain all manner of rare species. The approach seeks merely
to redress somewhat the losses of seminatural vegetation that are occurring.
The alternative is that yet more highly productive grazing land will be
created in reinstatement, irrespective of location. This misconception con-
cerning the overall approach, unfortunately, continues.
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RESTORING DERELICT LANDS IN GREAT BRITAIN
CONTRIBUTION OF ECOLOGICAL KNOWLEDGE
267
A Peak Park Planning Board official has described the Longstone Edge
trials discussed here as "the most exciting piece of reinstatement work
which has been undertaken within the area." The excitement had two
sources. First, the resulting sward is diverse and contains many of the
elements of seminatural calcareous grassland. The presence of these char-
acteristic species is the result of both deliberate introductions of propagules
and chance invasions. Even 12 years after establishment, the grasslands
are still acquiring additional species. Second, development of these tech-
niques marks an important departure from previous approaches to rein-
statement.
Formerly, reclamation was based on agricultural technology with re-
medial measures, so the environment was modified primarily by fertil-
ization to support the species sown. The scheme adopted on Longstone
Edge was based on a more objective ecological approach. In the simplest
terms, it can be described as an attempt to sow species capable of surviving
under the environmental regime of the limestone subsoils. The change in
emphasis was possible because the objectives of reinstatement were re-
considered and ecological theories concerning the control of community
composition were reappraised. Development of theory was particularly
useful in two respects: it could be used to explain the composition of
seminatural communities in the area and the grassland chronosequence
studied early in the research (it was on the basis of these field observations
and the literature on the effects of fertilizers on grassland diversity that
the more intuitive experiments were established), and, during interpre-
tation of the experimental results, it enabled success and failure to be
explained, rather than merely noted.
There is one major criticism of the work. Covering no more than 2 ha,
the plots are at best large trials. With one exception, they have yet to be
scaled up. Although increased scale should not affect the outcome of
reinstatement, it would establish whether the approach is usable on an
industrial scale. The possibility of developing a "wildflower" mixture
for reinstatement schemes based on commercial sources of native species
has been considered and rejected. Commercial seed is prohibitively ex-
pensive, but there are more serious ecological objections to such a mixture.
The research was developed in an attempt to avoid the previous approach-
namely, producing a recipe to be applied in all situations even if it could
guarantee a visually attractive grassland. The species that are available in
commercial quantities constitute inappropriate ecotypes. For example,
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SELECTED CASE STUDIES
native populations of Lotus corniculatus figured prominently and suc-
cessfully in the experiments, and this species seems to be useful in rein-
statement, whereas commercial material is a robust, erect ecotype from
central Europe that is selected for its high yield and ease of harvesting
and is quite unlike the calcareous grassland ecotype found on Longstone
Edge. Hand collection of local ecotypes is far more satisfactory, but its
feasibility and, more important, its impact on local populations are not
known. Some form of bulking up might be required, because large quan-
tities of seed could be involved. Wells (1983), for example, recommends
up to 2 kg/ha for some species. These practical considerations must be
resolved.
Work on Calluna has been scaled up by other workers, and the creation
of Calluna heathland has generated considerable interest. Large areas of
moorland and heath over much of the United Kingdom are degraded and
in need of reinstatement. In addition, serious visual intrusion has resulted
from the use of traditional methods of reinstatement in the revegetation
of such developments as pipeline rights of way. Reinstatement of Calluna
heathland is now feasible on a large scale as a result of further field trials
(Meaden, 1984; Moorland Restoration Project, 1983; Putwain et al., 19821.
The Longstone Edge research has stressed the necessity for a long-term
perspective in analyzing the results of reinstatement schemes. Results over
short periods can have misleading implications for small-scale pilot schemes.
Differences that were encountered in these trials over time could be ex-
plained by applying theories of community ecology.
The main value of the case described here concerns the interrelationship
between theoretical ecology and applied ecology. The study has provided
experimental support for theories of community ecology, and theoretical
considerations, particularly of plant strategy and community ecology, help
to weld the experimental work into a coherent whole. This unity converts
what might have been regarded merely as an interesting set of empirical
observations on a set of reinstatement trials on a small site in Derbyshire
into a radical alternative strategy for the revegetation of derelict and des-
poiled land.
ACKNOWLEDGMENTS
The work described here was undertaken in collaboration with my
research supervisor, Oliver Gilbert, and formed the basis of a doctoral
thesis submitted to the University of Sheffield in 1976. The work was
funded by a research studentship from the Natural Environment Research
Council. The assistance of the mining company, Laporte Industries Ltd.,
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RESTORING DERELICT LANDS IN GREAT BRITAIN
269
and Jack Harwood in providing facilities for this work is gratefully ac-
knowledged. The research should be regarded as the joint work of Oliver
Gilbert and me, but the observations and interpretation of events included
in this report are my responsibility.
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Committee Comment
An increasingly important activity of environmental scientists is the
reinstatement and reclamation of derelict land that has been modified for
various reasons with various outcomes. Reclamation practices are most
highly developed in the densely populated countries of western Europe,
where human modifications affect virtually every piece of terrain. Much
of this experience is summarized in a valuable book by A. D. Bradshaw
and M. J. Chadwick, The Restoration of Land, published in 1980. In-
creasing interest in this subject in the United States is reflected in the
launching of a new journal, Restoration and Management Notes, published
by the University of Wisconsin Arboretum. As in most fields of applied
ecology, early attempts at restoration relied almost entirely on an empirical
approach try a variety of approaches and see which ones work best.
They were also highly constrained by cost, availability of materials for
revegetation purposes, and the objectives expressed by society for rein-
statement projects.
Happily, the combination of several factors has resulted in important
changes in the practice of restoration. Society is placing increasing value
on land restoration, plant ecology has seen substantial recent development
of relevant theory and data, and the goals of restoration have become
much more sophisticated than merely getting something pretty and green.
The project at Longstone Edge is an admirable example of applied ecology.
It showed the importance of drawing on a variety of sources such as
ecological facts, ecological theories, analog studies, and the reasoned
judgment of persons familiar with the local areas if sound solutions are
to be achieved.
The Longstone Edge project took its direction from the recognition that
most derelict land in Britain occurs on nutrient-poor soils and that attempts
to make such areas fertile in the long run require repeated fertilization,
which, because of its cost, is seldom feasible. But it was observed that
diverse natural grasslands often occurred on nutrient-poor sites; appar-
ently, therefore, the site could be ecologically interesting without being
productive. These important observations played a role in the development
of the powerful experimental design that was used in this project.
Species-rich swards can be established on nutrient-poor soils when
constituent species are poor competitors characterized by low maximal
growth rates and when little competitive exclusion of species occurs. Under
rich soil conditions, a few of the strongest competitors often come to
dominate that is, interestingly, an empirical observation for which there
is no satisfactory theoretical explanation. We do not understand compe-
tition among plants in enough detail to be able to identify the mechanisms
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RESTORING DERELICT LANDS IN GREAT BRITAIN
273
of interactions. Restoration projects might turn out to be especially val-
uable for gaining further knowledge about these fundamental processes.
They are carried out on a scale larger than is usually possible in purely
academic research and, given current interest in them, are likely to be
followed long enough to reveal aspects of the processes whose outcomes
require decades and longer to be seen.
Better understanding of competition among plants might offer new
insights into the practical problems of reinstatement. For example, the
Longstone Edge project used primarily information on relative growth
rates to assess long-term success of species on the site. Other factors that
influence interactions among plants, such as growth form and the relative
allocation of resources to different tissues and organs, might also be used
in the selection of species for seeding of experimental plots.
Similarly, since the initiation of the Longstone Edge project, consid-
erable progress has been made ire understanding the role of particular
combinations of nutrients in determining the outcome of competition among
plants, particularly algae. The experimental results and a theoretical inter-
pretation of them have been provided by Tilman (19821. Because derelict
lands are likely to be diverse in their nutrient status, even if they are
mostly on poor soils, better understanding of the importance of particular
combinations of soil nutrients for the success of competing plant species
should enable both better selection of species for colonization and the
cultivation of specific genotypes for use in particular circumstances.
Restoration ecology might also contribute substantially to our knowl-
edge and understanding of seed banks in the soils and their roles in the
development of vegetation after disturbance. In the Longstone Edge
project, important use was made of topsoil with seeds; this technology
appears to have great potential. New advances in the understanding of the
causes of seed longevity and the specific conditions that result in termi-
nation of dormancy in various species might reveal which species have
seeds that persist well in different circumstances.
An important lesson of the Longstone Edge project is that in restoration
ecology there are unlikely to be formulas of broad applicability that can
be used in restoring most derelict lands. Solving problems for a particular
site will inevitably require knowledge of its environmental conditions and
of the genotypes of local plants that are potential colonizers of the site.
Nonetheless, general concepts such as the relationships among soil nu-
trients, growth rates, and competition are likely to be broadly applicable.
In addition, society is likely to have multiple goals for reclaimed lands.
Many sites in North America, for example, unlike those in Britain, are
on potentially valuable agricultural land or are in highly productive sites
that are to be restored to some seminatural state. Thus, apart from highly
;
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specific knowledge of local conditions, continued developments in the
theory of competition, plant succession, seed ecology, and plant nutrition
are likely to remain vital to restoration ecology far into the future.
References
Bradshaw, A. D., and M. J. Chadwick. 1980. The Restoration of Land. Blackwell, Oxford,
Eng.
Tilman, D. 1982. Resource Competition and Community Structure. Princeton University
Press, Princeton, N.J.
Representative terms from entire chapter:
derelict lands
