BOSCOMBE CLIFF AND OVERCLIFF
OUTLINE MANAGEMENT PLAN
March 2004
INTRODUCTION
Bournemouth’s sea cliffs extend for approximately 8km from the Borough of
Poole boundary east to the Point House café in Southbourne. Including the
overcliff, they cover an area of approximately 45 hectares.
Generally the cliffs and overcliff are known to support a diverse and
interesting flora and fauna with a number of rare species present.
In recognition of this fact and because of the presence of some important
geological exposures, areas of the cliffs are designated as Sites of Special
Scientific Interest (SSSI).
The majority of the area outside of the SSSIs is designated as a Site of Nature
Conservation Interest.
A vegetation survey of the cliffs was carried out in 1993 by the Dorset
Ecological Consultancy (Walls 1993) and a sand lizard Lacerta agilis survey of
the cliffs between the piers was undertaken in 1994 by the Herpetological
Conservation Trust (Corbett 1994). Otherwise there has been little formal
ecological monitoring on this valuable resource.
It is widely recognised that some major active habitat management is
required to maintain the ecological interest of the cliffs and overcliff.
This is particularly the case in respect of the increasing prevalence of
invasive, non-native plant species such as hottentot fig Carpobrotus edulis.
A small area of cliff to the west of Boscombe Pier is currently managed by the
Herpetological Conservation Trust as a Nature Reserve.
Following discussion with various groups and individuals and because of the
varied ecological interest of the cliff and overcliff in the vicinity of Portman
Ravine, it has been resolved that a management plan be produced for this
site. The site location is shown on Map 1.
SUMMARY
This outline management plan sets out to describe and evaluate the area and
to prescribe a workable management programme.
While it is taken into account that the area has a high amenity and
recreational value, the plan is geared towards conservation management.
The plan is divided into three stages:
Description – a brief description of the site providing a general background
on which to base a management policy.
Ecological evaluation and objectives – a summary evaluation from an
ecological perspective and an account of the principle management
objectives.
Prescription – describes the actual managements of the site and how these
will be put into practice.
1
DESCRIPTION
1.1
General information
Portman Ravine is situated approximately 1.3km east of Boscombe
pier midway between Shelley Park and Fishermans Walk.
The area covered by the management plan comprises both cliff face
and overcliff as shown on Map 2 and is approximately 5.7ha in extent.
It is owned by the Leisure and Tourism Directorate with the overcliff
the responsibility of Leisure Services and the cliff the responsibility of
Seafront Services.
1.2
Environmental information
1.2.1
Physical
The cliffs are composed of soft Tertiary sands and clays of the
Bracklesham and Bagshot series. In places such as the overcliff there
is a thin topping of plateau gravels and wind-blown sand.
1.2.2
Biological
1.2.2.1 Habitat types and associated species (see map 3)
Scrub
The predominant scrub species is common gorse Ulex europaeus,
but there ae also significant areas of bramble Rubus fruticosus and
holm oak Quercus ilex. A number of garden shrub species are well
established including Hebe, Griselinea, Escallonia and Duke of Argyll’s
tea tree.
Ruderal and short grass
The light, sandy, free-draining soils support an interesting community
of annuals and drought-resistant plants. Characteristic plants include
squirrel-tail fescue Vulpia bromoides, early hair-grass Aira praecox
and stag’s-horn plantain Plantago coronopus.
A range of nationally rare and scarce species is present including
hairy bird’s-foot-trefoil Lotus subbiflorus, mossy stonecrop Crassula
tillea and some of the scarce clovers Trifolium spp.
Again a number of garden plant species are established such as
stonecrops Sedum spp, Alyssum Alyssum saxatile and candytuft Iberis
sempervirons.
Dune grasses
On both the cliff and the Overcliff are areas dominated by marram
Ammophila arenia and lyme grass Leymus arenarius. These are
typical early colonists of loose sand and play an important role in
stabilisation, paving the way for colonisation by other species.
Wet flush/seepage
There is a seepage line to the east of the Portman Ravine zigzag
created by an impervious layer in the strata. Here water reaches the
surface and an interesting plant community has developed. Of
particular interest is the royal fern Osmunda regalis a plant made
scarce by over-collecting in Victorian times.
Bare ground
The more vertical sand cliffs tend not to be vegetated and are a
valuable habitat in their own right, particularly for a range of
burrowing insects and nesting sand martins. Other less steep areas of
open sand provide suitable habitat for a variety of invertebrates and
are particularly important as egg laying sites for sand lizard Lacerta
agilis, green lizard L. viridis and wall lizard Podarcis muralis.
The stone walls of the zigzag path are utilised by wall lizards. They
live in the crevices between the stones and can often be seen basking
on the walls themselves.
1.2.3
Present management
Management of the cliff face has been minimal and certainly no
specific habitat management work has occurred in this area.
The overcliff has been quite intensively managed for amenity
purposes with most of the grassland regularly mown.
Several tarmac footpaths traverse the site and these are kept clear of
encroaching vegetation.
Benches are situated throughout as are waste bins.
2
Ecological evaluation and objectives
2.1
Evaluation
A range of habitat types are represented that support a diverse flora
and fauna. In recognition of this, the overcliff and a large part of the
cliff are designated as a Site of Nature Conservation Interest (SNCI).
See Map 4.
A number of rare species (both plant and animal) occur and the site is
particularly interesting because of its reptilian fauna.
Common lizards Lacerta vivipara are numerous and there are
populations of both wall lizard and green lizard. The latter 2 species
are not native to mainland Britain and have evidently been introduced
to this site although it is not clear when the introduction occurred or
whether it was deliberate or accidental. Both species are thriving here
and there is evidence of successful breeding. Although they are not
expected to have any negative impacts on native wildlife, the
populations will need to be carefully monitored, especially in respect
of sand lizard status.
There have been recent sightings of sand lizard and appropriate
habitat management would provide suitable conditions for this rare
animal.
To date there has been no formal surveying of other animal groups
but general observation has revealed a diverse fauna.
Several species of bird breed in the area including meadow pipit
Anthus pratensis, stonechat Saxicola torquata and Dartford warbler
Sylvia undata. A small colony of sand martin Riparia riparia nest in a
sand cliff to the east of Portman Ravine.
Butterflies are a feature of the area with species recorded including
Essex skipper Thymelicus lineola, common blue Polymmatus icarus,
marbled white Melanargia galathea and clouded yellow Colias
croceus. Portman Ravine was in fact the first UK location where
clouded yellow were observed to breed and to survive the winter in
1998/99. Eggs, larvae and an emerging adult were also observed in
December 2002/January 2003.
Surveys would undoubtedly reveal a diverse invertebrate fauna but
casual observation has already revealed some less common, localised
species such as long-winged conehead Conocephalus discolour, grey
bush-cricket Platycleis albopunctata and the bee killer wasp or bee
wolf Philanthus triangulum. The possible presence of the rare cliff
tiger beetle Cicendela germanica requires confirmation.
The predominantly acid free-draining soils coupled with harsh and
variable climatic conditions and other environmental factors such as
salt spray and unstable slopes have resulted in the development of
specialist plant assemblages. These include some nationally rare
plants as described previously. Unfortunately, these natural plant
communities are being damaged and, in some areas, displaced by
introduced plant species.
2.1.1
Alien plant species
A whole range of non-native plant species thrive on the cliffs and
many coexist with the native flora with no particular detrimental
impact. However, there are others that are thriving at the expense of
the native wildlife. Hottentot fig Carpobrotus edulis is becoming a
dominant feature over large areas where it is completely
overwhelming all other vegetation and is even encroaching over sand
cliffs.
Several non-native tree and shrub species have become well
established such as holm oak and garden privet Ligustrum
ovalifolium. These tend to form dense stands under which nothing is
able to grow.
2.1.2
Native shrub species
The presence of native shrubs such as gorse is problematic in some
areas, especially close to paths, because of the inherent fire risk. In
addition, the dominance of gorse can be at the expense of other
native plants.
2.2
Objectives
1. To initiate surveys and monitoring programmes in respect of plant
and animal communities.
2. To reverse the current trend of native habitat loss to invasive alien
species and to re-establish natural vegetation. This will involve the
eradication of hottentot fig and the removal of a significant amount of
non-native shrub and tree species.
3. To encourage the development of larger areas of marram/lyme
grass on the overcliff by reducing the area currently mown.
4. To initiate a gorse management programme with an initial
reduction in the area and subsequently a system of rotational
coppicing.
5. To ensure the zigzag path walls continue to provide suitable habitat
for the wall lizard colony. This will be achieved by not replacing any
missing pointing unless absolutely necessary in localised areas for
health and safety purposes.
6. To educate site users about the ecological importance of the site
through appropriate signage.
7. To encourage dog owners to dispose of their dogs’ waste in the
bins provided.
3
Prescription
3.1
Working compartments
To facilitate reference and description, the area has been divided into
6 working compartments as shown on Map 5. On the overcliff, paths
have generally been used to demarcate the compartment boundaries.
However, the eastern and western extremes of the cliff compartment
are more arbitrary and can essentially be taken to follow a line from
the overcliff extremities.
For each compartment a brief description is given and the required
management is then discussed. This is shown in map form with Map
6 showing the desired state of the site and Map 7 giving a summary
of the management required to achieve this state.
3.1.1
Compartment 1
Description
This is the area between the cliff top fence and the main central
footpath to the west of Portman Ravine zigzag. It largely comprises
open grassland that is mown and tends to be heavily trampled. There
are some areas of gorse especially towards the eastern edge of the
compartment along with further small blocks of oak and privet scrub.
Towards the western edge of the compartment, the central path is
bordered by marram and lyme grass.
There are 4 commemorative benches within the compartment.
Most of the scrub areas are used by common and green lizards as is
the dense marram and lyme grass on the path edge. This was also
the location of the most recent sand lizard sightings.
In places the grass is very worn and sparse creating the ideal habitat
for burrowing wasps and solitary bees. Of particular note is a colony
of bee wolf.
Management
It is proposed to cease any mowing operations with a view to
encouraging the spread of marram and lyme grass and other
associated grass and herb species.
This will provide additional habitat for reptiles such as sand lizard as
well as for a range of invertebrate species. It is important though that
some short sward areas are retained as these support rare annuals
and burrowing bees and wasps as previously described. Almost
undoubtedly such habitat will be maintained by trampling and it may
be necessary to use temporary fencing to allow the development of
areas of taller vegetation.
Where gorse abuts the main path, it will be cut back approximately
2m from the path edge to reduce the fire risk.
If possible it would be beneficial to move benches presently located
towards the centre of the compartment to the periphery.
3.1.2
Compartment 2
Description
This is a small area towards the centre of the site surrounded by
tarmac paths. The majority of the area comprises sparse, low growing
gorse interspersed with short grass and bare earth. The western edge
is dominated by a stand of dense mature gorse and the southern
edge is fringed by marram and lyme grass.
Common, wall and green lizard occur here and grey bush-cricket was
recorded in 2003.
Management
The mature gorse block will be removed to encourage the spread of
tall grass and herb species.
Where other gorse is growing to the path edge it will be cleared to a
width of approximately 2m.
It may be necessary to periodically cut back other gorse to retain
areas of bare earth and short grass.
3.1.3
Compartment 3
Description
This is the area between the clifftop fence and the main central
footpath running eastwards from comp. 2. Its eastern boundary is an
arbitrary line running to the cliff top fence from the junction of the
main footpath and the linking path to the main road immediately east
of Dingle Road.
The whole area is open grassland, the majority of which is a shortmown sward. However, an area adjacent to the clifftop fence has
been left unmown allowing the development of a marram/lyme grass
dominated sward. This provides a link with the marram-dominated
cliff face at this point and is ideal habitat for sand and green lizard
and for a variety of invertebrate species, in particular orthopterans.
There are 2 commemorative benches, one of which is situated in the
centre of the compartment.
Management
Mowing of the grass will cease to encourage the spread of the well
established dune grasses. There may be a requirement for some
temporary fencing to prevent trampling during the initial stages of
establishment.
Ideally, the bench in the centre should be moved the periphery.
3.1.4
Compartment 4
Description
This is essentially the whole cliff area including the Portman Ravine
zigzag between the cliff top fence and the beach promenade wall.
The eastern and western boundaries are not readily definable but
approximate to those of the overcliff.
The cliff has a complex and dynamic assemblage of habitats that are
difficult to relate to recognised plant communities except over small,
isolated areas. This is largely due to the presence of a range of nonnative species of herbs, shrubs and trees.
There are considerable areas of bare ground especially on the steeper
slopes which in some cases are practically vertical. One of these
vertical cliffs is a nesting site for sand martin.
Dartford warbler successfully bred here in 2003.
In parts the bare ground grades into sparse vegetation cover with
discrete areas of taller marram and scattered gorse, but generally
scrub is tending to dominate at the expense of this desired habitat
structure. The scrub is dominated by common gorse but there are
substantial stands of non-native species such as garden privet,
Griselinea and holm oak.
To the east of the zigzag is an area of wet flush dominated by
common reed with several plants of royal fern.
Throughout, there are substantial areas of hottentot fig that are
rapidly spreading to the detriment of any native vegetation and even
bare ground.
The zigzag path is flanked on either side by stone/concrete block
walls. The southerly facing walls provide ideal habitat for a thriving
population of wall lizard especially where sections of pointing are
missing providing crevices between the stones.
Management
The 2 main priorities are:
1. To eradicate the hottentot fig and the non-native shrubs.
2. To reduce the area of gorse by approximately 50%.
The hottentot fig can be treated with a glyphosate-based herbicide
and removed from site when completely dead. This process will
create large areas of bare ground that will eventually recolonise
naturally. However, the option of seeding with appropriate species
could be investigated if thought necessary.
There will be a phased removal of the scrub, concentrating initially on
the non-native species.
The desired state is an area dominated by marram grass and
associated herb species contiguous with a similar habitat on the
seaward edge of the overcliff. There should be areas of bare ground
and short vegetation and scattered gorse scrub. It would be expected
that ericaceous species would also become established to a limited
extent.
To benefit the wall lizard colony along the zigzag, there will be no repointing of the walls unless essential from a health and safety
perspective. It is also essential that the wall top vegetation is not cut
back too severely as this provides necessary cover for animals
adjacent to their basking spots.
3.1.5
Compartment 5
Description
This is the whole of the area to the north of the main central
footpath. The western boundary is the footpath running from the
main road immediately to the west of Browning Avenue. The eastern
boundary is the footpath running from the main road to the east of
Dingle Road.
It comprises a mix of short mown grassland and some substantial
blocks of common gorse. There are also some blocks of holm oak
especially along the roadside.
The short, sparse turf is ideal habitat for a number of less common
annual grass and herb species. Common lizard utilise the edges of the
gorse blocks which also provide nesting and feeding sites for a variety
of birds including stonechat and Dartford warbler.
There are several bench seats and a shelter within the compartment
boundary.
Management
The compartment will continue to be managed primarily for amenity
purposes with the present grass mowing regime continued. However,
a 2m fringe of grass will be left unmown around any gorse blocks and
the fringing dune grasses alongside the central path at the western
end of the compartment will be left. There is also scope to leave
other small areas unmown that tend not to be used for amenity.
The larger gorse blocks will be broken up into smaller units by
selectively removing areas that have become ‘leggy’. This will not only
produce more valuable ‘edge’ habitat but will also reduce the risk of a
major fire.
Any gorse adjacent to a footpath will be cut back to a width of at
least 2m.
There will be a phased removal of the holm oak that is presently
shading out other vegetation.
3.2
General items
Timing of habitat management work
All work will be undertaken between mid-October and February
inclusive to ensure minimal damage to existing wildlife and its
habitats.
Regular maintenance
On the overcliff the Council’s grounds maintenance staff are
responsible for tasks such as litter clearance, path maintenance, grass
mowing and the upkeep of benches. This work will be carried out to
required specifications.
Council byelaws and Dogs (Fouling of Land) Act 1996
The overcliff is subject to byelaw control. The Dogs (Fouling of Land)
Act 1996 applies to all Open Space within the Borough and requires
any dog owner to collect their dog’s faeces and dispose of it
appropriately. On the overcliff there are dog waste bins provided for
this purpose.
Interpretation signage
As a means of informing site users of the ecological significance of
the area and the reasoning behind the management policies,
information boards will be designed and installed at appropriate
locations.
References
Walls, R. M. 1993 The vegetation of the Bournemouth Cliffs
Corbett, K 1994 Sand lizard survey of Bournemouth Cliffs between Piers
APPENDIX
5 YEAR MANAGEMENT SUMMARY
Year 1 – 2004/05
Cliff
Chemical treatment of Hottentot fig
Scrub clearance (inc. stump treatment & follow-up spraying)
£3600
Overcliff
Grassland management
Gorse coppicing and clearance
Holm oak removal
Footpath maintenance
£3000
Year 2 – 2005/06
Cliff
Removal of treated Hottentot fig
Scrub clearance (inc. stump treatment & follow-up spraying)
£4400
Overcliff
Grassland management
Gorse coppicing and clearance
Holm oak removal
Footpath maintenance
£3100
Year 3 – 2006/07
Cliff
Follow-up maintenance (clearance, coppicing, spraying as required)
£1000
Overcliff
Grassland management
Gorse coppicing and clearance
Holm oak removal
Footpath maintenance
£3250
Year 4 – 2007/08
Cliff
Follow-up maintenance (clearance, coppicing, spraying as required)
£500
Overcliff
Grassland management
Gorse coppicing and clearance
Holm oak removal
Footpath maintenance
£3400
Year 5 – 2008/09
Cliff
Follow-up maintenance (clearance, coppicing, spraying as required)
£500
Overcliff
Grassland management
Gorse coppicing and clearance
Holm oak removal
Footpath maintenance
£3500