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A Quantitative Survey of Chalk Grassland in England
J. W. BLACKWOOD
The Nature Conservancy (East Anglia Region), Sandbanks, Saltfleetby, Louth, Lincolnshire, England,
&
C. R. TUBBS,
The Nature Conservancy (South Region), Shrubbs Hill Road, Lyndhurst, Hampshire, England
ABSTRACT
to give way before an encroaching tide of arable, the
trend being accelerated during the scare-price period
Precise quantitative information about habitats & important both in considering their conservation and in laying a of the Napoleonic Wars. It is doubtful whether the
foundation for more detailed systematic study. This article total acreage of chalk grassland in England in 1815
records a quantitative survey of chalk grassland in England excessively exceeded that of the present time. Naish,
in 1966, and demonstrates the practicability of effecting
rapid national habitat surveys. The survey revealed that,
despite progressive "reclamation', there remained in England
at that time a minimum of 107,605 acres (43,546 ha) of
chalk grassland, of which almost 70 per cent lay in the
county of Wiltshire. Observations indicated that most of
these areas of chalk grassland were used as sheep and cattle
grazing, and were on escarpments too steep to reclaim.
Distribution of C h a l k O u t c r o p s in E n g l a n d a n d
Percentage of O u t c r o p O c c u p i e d b y C h a l k
Grassland f o r E a c h C o u n t y or T o p o g r a p h i c a l
Unit.
Yorkshire W o l d s
15
:::::
Lincolnshire W o l d s
~"
INTRODUCTION
Until the closing decades of the 18th century,
unsown grassland, mainly sheep-walk, occupied vast
areas of the chalklands of lowland Britain. In the 15th
and 16th centuries, the area of sheep-walk would
appear to have expanded partly in response to rising
market-prices for wool, and partly because considerable sheep flocks were necessary to the maintenance
of arable production. The chalkland areas were
essentially sheep-and-corn country. The sheep, r u n
on the open downs by day, were folded overnight
on the arable land. The latter benefitted both from the
sheep's dung and from the consolidation of the light
soils by trampling. Kerridge (1951) concluded that, in
Wiltshire, 'without the sheep-fold the whole agricultural economy would necessarily have collapsed.'
In the 18th century, and probably before, the
emphasis swung towards arable production. Although
the sheep-fold remained indispensable as the chief
source of manure, technical innovation (mainly the
introduction of the new fodder-crops and legumes, and
the widespread irrigating of water-meadows) made it
possible to incorporate sheep husbandry into the
management of the new enclosed arable farms, arising
largely from the increasing numbers of Enclosure
Acts. Thus the vast tracts of open downland started
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Dorset 3.5
152
Fig. 1. Sketch-map of chalk outcrops in England, with
indications of percentage of each area occupied by chalk
grassland.
(1961), using surveys published in 1791, 1807, 1825
and 1840, demonstrated a rapid reduction and fragmentation of the area of downland sheep-walk in
Hampshire until, at the last mentioned date, it
occupied very little more than its present area. Subsequently, there has been an ebb and flow of 'reclamation' and abandonment of arable, corresponding to
Biological Conservation, Vol 3, N o . 1, O c t o b e r 1 9 7 0 - - O Elsevier Publishing C o m p a n y Ltd, E n g l a n d - - P r i n t e d in Great Britain
Biological Conservation
the level of investment in arable production. The fragmentation of the 'old down' or chalk grassland, however, has been progressive, and at the present time
it seems clear that reclamation for arable farming, etc.,
has reached its highest ever level.
Chalk grassland characteristically carries a rich flora
(Wells, 1969) and invertebrate fauna (Morris, 1969).
The formerly extensive tracts also attracted a distinctive avifauna. The attention of biologists, however, has
generally been focussed on a limited number of wellknown sites, and few quantitative data relating to the
total extent, management, and fragment-size, of chalk
grassland are available.
The objects of the survey recorded here were twofold: first to demonstrate the practicability of carrying
out rapid and extensive quantitative habitat surveys,
and secondly to obtain quantitative data for chalk
grassland as a basis for further systematic study. The
field-work in this case occupied 82 man-days and was
carried out mainly by the authors and N. E. King (who
surveyed Wiltshire). The actual mapping was completed between April and September 1966 at a scale of
1:25,000. (Fig. 1). The maps are held by the Nature
Conservancy and are available for reference on
request.
DEFINITION OF HABITAT AND METHOD OF SURVEY
The survey was necessarily extensive rather than
intensive. In the time available it was not possible to
investigate in detail the soils and vegetation of each
individual site. For the purpose of the survey, therefore, the habitat was defined as unsown grassland on
soils of which the parent material was chalk. This was
considered more appropriate than the definition of
specific plant communities on chalk soils, and was in
fact the primary definition of chalk grassland adopted
by Tansley & Adamson (1926).
The definition does, however, introduce some element of subjective judgement in an extensive survey
such as that described here. For example, sites which
had clearly received treatment with herbicides, but
which retained a proportion of chalk grassland herbs
and grasses, were excluded. On the other hand areas
of abandoned arable (few in number and mostly small
in area) were included where it was known that for
peculiar reasons (e.g. National Nature Reserve status)
no further cultivation would take place on them. Small
areas of grassland arising on superficial deposits overlying the chalk and isolated within extensive tracts of
chalk grassland were also included. Sites carrying
more than a 50 per cent cover of scrub were excluded
from the survey; areas of chalk grassland of less than
five acres (two hectares) were not recorded.
Areas were estimated by using a transparent grid
superimposed on the survey maps. Within each grid
square, a block of dots was printed for the estimation
of parts of squares. The areas estimated in this way do
not include a correction for steep slopes where the
true surface area is greater than that shown on the
map.
RESULTS
The data obtained from the survey are summarized
in Table I, which refers to 107,605 acres (43,546 ha) of
chalk grassland grouped, as appropriate, according to
the administrative county or topographical unit
involved. This total area was distributed in 1,225
separate fragments, of which 931 or more than threequarters, were of less than 50 acres (20 ha) but more
than 5 acres (2 ha) in extent. Only 67 sites with an
area in excess of 200 acres (81 ha) each were recorded.
As sites of less than five acres (2 ha), together with
roadside verges, railway embankments, and small
artefacts such as chalk quarries and earthworks, were
not included in the survey, the recorded acreage falls
short of the true total area of the habitat. It should
also be stressed that the figures in Table I represent the
mapped and not the projected area, and that the
greater part of the grassland is on steep slopes.
Both the distribution and survival of the chalk
grasslands recorded in the survey depend on two main
factors: the occurrence of escarpments too steep to
cultivate, and the use of certain areas of the chalk for
military training. In addition, a few sites receive protection from 'reclamation' because they are Nature
Reserves, Public Open Spaces, National Trust property, or common lands, or are protected by a private
owner. In most cases these are on escarpments too
steep to reclaim.
Table I shows that only in Wiltshire, Dorset,
Hampshire, the South Downs, the Yorkshire Wolds,
and the Isle of Wight, does the area of chalk grassland
exceed one per cent of the area of the chalk outcrop,
and that fragments of more than 200 acres (81 ha)
are almost exclusively confined to these areas. Perhaps
the most striking feature of the Table is the large area
of chalk grassland--73,085 acres (29,576 ha)--and the
large number of fragments of more than 200 acres,
situated in Wiltshire. This circumstance is accounted
for in part by the extensive military training areas on
Salisbury Plain, and in part by the varied topography
of the county. Those counties or topographical units
in which the area of chalk grassland was less than
one per cent, exhibit only a limited distribution of
escarpment (e.g. Norfolk) or are extensively wooded
(e.g. the Chilterns).
Blackwood& Tubbs: A Quantitative Survey of Chalk Grasslandin England
TABLE
I
Chalk Grassland Survey 1966: Summary of Data Obtained
No. of fragments by size categories
(acres*)
County or
%
~
%
topographical unit
~
~
~~ ~
~
~ ~
~ ~
o
Dorset
~
~?
~
¢',1
¢m
+
236,880
3-5
145
101
28
10
2
1
3
73,085
464,400
15'7
529
407
51
34
16
5
16
Hampshire
5,224
239,760
2.2
119
95
13
7
1
--
3
Berkshire
1,573
185,400
0'8
59
50
7
2
--
--
--
Isle of Wight
2,128
14,040
15.2
24
13
6
2
--
2
1
South Downs (Sussex)
8,592
223,200
3"8
117
83
13
11
2
1
7
North Downs (Kent and Surrey)
2,226
437,760
0.5
94
83
10
1
--
--
--
Chiltern Hills (Beds., Berks.,
Bucks., Herts., and Oxon.)
2,028
550,080
0"4
59
47
7
4
--
--
170
156,600
0.1
3
2
1
44
332,640
0.01
3
3
.
225
143,280
0.2
12
12
.
3,939
262,440
1'5
61
35
15
5
4
2
--
107,605 3,246,480
3.3
1,225
931
151
76
26
11
30
Wiltshire
Cambridgeshire
Norfolk
Lincolnshire Wolds
Yorkshire Wolds
TOTAL
8,371
.-.
1
.
.
.
.
.
.
.
.
.
.
.
.
.
* 1 acre = 0"405 ha.
A brief appraisal of the distribution and management of chalk grassland in each county (or topographical unit) follows, using Table I together with
notes made in the field and other information gathered
during the survey.
Wiltshire
Wiltshire has almost 70 per cent of the total area of
chalk grassland in England, including 37 sites of more
than 200 acres (81 ha). The Ministry of Defence
training areas on Salisbury Plain account for slightly
less than half the county's chalk grassland acreage, or
7.4 per cent of the county's chalk outcrop. Intensive
grazing is here confined to the periphery of the
training areas, but great tracts of the Imber Ranges are
extensively grazed by large herds of cattle which are
'drifted' across the Ranges when they are not in use.
Previous to their acquisition early in this century,
many of the training areas were in arable cultivation,
which is perhaps reflected in the widespread abundance
of Tall Oat-grass (Arrhenatherum elatius) and Upright
Brome-grass (Bromus erectus). The ranges as yet exhibit
little scrub development--probably because much of
their extent is comparatively remote from hedgerow
Hawthorn (Crataegus monogyna) which might provide
seed sources.
The remaining chalk grasslands in Wiltshire are
almost all on scarp slopes--the scarp of the Marlborough Downs overlooking the Vale of Pewsey, the
edges of Salisbury Plain, and the numerous chalk
ridges of southern Wiltshire. Practically all are retained as sheep or cattle grazings which form integral
parts of farm units. Grazing management has resulted
in the retention of characteristically 'clean' slopes, few
sites exhibiting scrub colonization.
Dorset
The 8371 acres (3388 ha) of chalk grassland recorded
in Dorset are distributed mainly along the Purbeck
Biological Conservation
chalk ridge, along the northerly-facing scarp overlooking the Blackmoor Vale, and on the sides of dipslope valleys. As in Wiltshire, practically the whole of
the total area (apart from the military training area on
Purbeck ridge) is grazed by either sheep or cattle;
however, because of the more limited distribution of
steep slopes as compared with Wiltshire, the present
tide of cultivation has left fewer and relatively less
extensive areas of unsown grassland in Dorset. The
botanical composition of many steep slopes in northern
Dorset has also been partially modified by reseeding
and spraying. Hawthorn encroachment is generally
more widespread in Dorset than in Wiltshire.
Hampshire
Apart from three sites in excess of 400 acres (162
ha), one of which is an eastern extension of the
Salisbury Plain Ministry of Defence Ranges, another
is a Public Open Space owned by Hampshire
County Council, and the third is an actively managed
Common, the Hampshire chalk grassland is restricted
to a scatter of sites of less than 200 acres on steep and
uncultivable slopes. Most of those are either ungrazed
or grazed only occasionally, and hawthorn colonization
is a recurrent feature.
forms a chain of chalk grassland broken only by the
valleys of the Adur, Ouse, and Cuckmere, and by
woodlands between Washington and Steyning. On the
dip-slope, chalk grassland is confined to coombes and
trenches. Almost all the chalk grassland on the South
Downs is grazed and so relatively few sites have been
invaded by scrub.
North Downs
The scarp slope ranging from Guildford, Surrey to
Ashford, Kent contains scattered small fragments of
chalk grassland that are largely unmanaged and often
bear much scrub development. The dip-slope is
mainly wooded, being on a clay-with-flints capping
over chalk so that little chalk grassland was located.
Around Folkstone and Dover, steep-sided chalk
valleys and cliff edges produce a number of grassland
fragments most of which are grazed.
The Chiltern Hills
The 2028 acres (821 ha) of chalk grassland recorded
in the Chiltern Hills is confined almost entirely to the
north-west-facing scarp of the Upper Chalk in
Oxfordshire and Buckinghamshire. Colonization of
the scarp by scrub is common, and in several places
woodland is developing. Most areas of grassland are
Berkshire
clearly too small (59 fragments of which 47 were less
The ease with which the gently undulating plateau
than 50 acres (20 ha) in extent) to be managed as
of the Berkshire Downs can be brought into cultivation
economic parts of farm units. The dip-slope of the
in reflected in the small percentage (0.8 per cent) of
Chilterns is largely capped with drift and extensively
the chalk outcrop remaining as unsown grassland. The
wooded, and chalk grassland is confined to the sides
total area of chalk grassland, 1573 acres (637 ha), is
of a few valleys.
distributed in 59 fragments, of which 50 are between
five acres (2 ha) and 50 acres (20 ha) in area and none
of the remaining nine is more than 200 acres. Most of Cambridgeshire and Norfolk
the larger sites, however, are grazed and exhibit little
In the virtual absence of steep slopes, chalk grassscrub colonization.
land in these counties is confined to artefacts (i.e.
earthworks and quarries) and a single small glacial
scar at Ringstead Downs, Norfolk.
Isle of Wight
More than 2000 acres (809 ha) of chalk grassland,
representing about 15 per cent of the total chalk
Lincolnshire Wolds
outcrop, are found in the Isle of Wight. This high
Chalk grassland is here confined to artefacts such as
proportion of chalk grassland compared with arable
deserted medieval village sites and to a few steep
land arises partly from the incidence of steep slopes
slopes. These sites have been but little colonized by
and partly from the activities of the National Trust,
scrub and are mostly grazed by cattle or sheep.
whose interests in the island include extensive tracts of
chalk grassland, most of which is grazed by cattle.
Yorkshire Wolds
To the north and west the Wolds are segmented by
South Downs
West of the River Arun the South Downs of Sussex are complex systems of U-shaped glaciated valleys, the
extensively wooded, chalk grassland being confined to steep sides of which carry 3939 acres (1594 ha) of
a three-mile (4.8 km) stretch of the north-facing scarp chalk grassland according to our survey. Most such
and to a few smaller fragments on the dip-slope. From areas are grazed by sheep but a few have been colonized
the Arun to Beachy Head the steep north-facing scarp by scrub.
Blackwood & Tubbs : A Quantitative Survey of Chalk Grassland in England
ACKNOWLEDGEMENTS
W e wish to a c k n o w l e d g e the help o f o u r colleagues
M. J. W o o d m a n , G. M. A. Barker, R. D. Jennings,
N. E. King, a n d J. M. Schofield, in c a r r y i n g o u t this
survey. W e also wish to t h a n k T. C. E. Wells for
c o m m e n t i n g on a d r a f t o f this p a p e r , a n d R. A.
F e n t o n for p r e p a r i n g the m a p a c c o m p a n y i n g it.
References
KERRIDGE, E. W. J. (1951). The Agrarian History of
Wiltshire. Ph.D. thesis, University of London.
A Code of Conduct for the Conservation of Flowering
Plants and Ferns
In the interests of the Conservation of Flowering Plants
and Ferns it is suggested that members of the BSBI* consider the following recommendations as a guide to collecting, introducing, or visiting, rare and local species. The
Society hopes that all those interested in the conservation
of the Countryside will also follow these recommendations.
Collecting
1. Members will not pick or collect any material of
nationally rare species as defined in a listt published by the
Society.
2. Members will not collect specimens from any Nature
Reserve, Nature Trail, or National Trust property, without
first obtaining permission from the appropriate authorities.
3. Members will not collect specimens of any species in
a locality in which it is scarce.
4. When leading excursions, members will ensure where
possible that material is demonstrated without removing,
or severely damaging, the plant.
5. Members who find it necessary to collect voucher
material to support new County or other important
records should do so with discretion. It is rarely necessary
to take a whole plant to ensure accurate identification. A
photograph may be adequate in some cases.
6. Members who wish to collect plants for the preparation of duplicate sets of herbarium material should only
do so from very large populations. When material in the
field is insufficient, it should be cultivated for this purpose.
7. When living material is required for experimental
work, members should raise it from seed or cuttings
wherever possible. With modern methods of propagation,
uprooting of plants should rarely be necessary.
Note: If material of species in Clauses 1 or 2 is needed for
scientific purposes, reference should first be made to the
Secretary of the Conservation Committee of the Botanical
* Whereas this Code of Conduct was prepared for the members
of the Botanical Society of the British Isles, it is published by
us internationally with the happy approval of the Council of
that body, as it is felt that it will be of far wider interest and
could with advantage be followed in other heavily-populated
countries.--Ed.
-~ This will be published in an early number of the journal
Watsonia and may be subject to amendment from time to time,
MORRIS, M. G. (1969). Populations of invertebrate animals
and the management of chalk grassland in Britain.
Biol. Conserv., 1(3), 225-31.
NAXSH, M. C. (1961). The Historical Geography of the
Hampshire Chalklands. M.A. thesis, University of
London.
TANSLEY, A. G. & ADAMSON, R. S. (1926). Studies of the
vegetation of the English Chalk. IV: A preliminary
survey of the chalk grasslands of the Sussex Downs.
J. Ecol., 14, 1-32, illustr.
WELLS, T. C. E. (1969). Botanical aspects of conservation
management of chalk grasslands. Biol. Conserv., 2(1),
36-44, illustr.
Society of the British Isles, who will have access to the
latest information about the status of the species, and will
attempt to build up an index of sources of seed or living
material already available.
Visiting
1. Members must ensure that, when land is private, they
have adequate permission for access to the site.
2. Members should take care not to damage the site of
rare species by 'gardening' before taking photographs.
3. Photographs should not be exhibited or published
which disclose the locality of a rare species, nor should
details accompanying a photograph do this.
4. Members visiting the sites of rare species should be
aware that too many visitors can damage the habitat of a
plant by, for example, preventing seedling establishment.
It is suggested that parties numbering more than three are
often undesirable; larger parties may draw attention to the
site of rare species, and are more likely to cause damage to
the habitat. Members should always respect requests from
Conservation organizations not to visit sites at certain
times.
5. Members visiting rare species should always avoid
any activity, such as trampling around the plant, or creating
an obvious track, which would expose the plant to the
attention of unwelcome visitors.
6. Organizers of excursions should take these considerations into account when planning routes.
Introductions
Members must not introduce plants into the countryside, and especially into Nature Reserves, without the
knowledge and agreement of the appropriate conservation
organization. F o r further guidance on this subject, reference should be made to ' A Policy on Introductions',
SPNR Technical Publication No. 2, 1970, obtainable from
the Secretariat, SPNR, The Manor House, Alford,
Lincolnshire, England, for 15p.
E. MILNE-REDHEAD,
President, Botanical Society of the British Isles,
The Herbarium,
Royal Botanic Gardens,
Kew, Richmond,
Surrey, England