Case study: Sand dune ecosystem, succession and management
Ainsdale dunes, Sefton Coast, Lancashire
The Sefton Coast is the largest dune area in
England. It is a coastline subject to natural
change.
Ainsdale Sand Dunes National Nature
Reserve (NNR) totals 508 ha and forms
part of the Sefton Coast, the finest dune
system on the north-west coast of England.
The NNR contains a range of habitats,
including intertidal sand flats, embryo
dunes, high mobile yellow dunes, fixed
vegetated dunes, wet dune slacks, areas
of deciduous scrub and a predominantly
pine woodland.
Key species include sand lizard,
natterjack toad, great crested newt, red
squirrel, dune helleborine and pendulous
flowered helleborine. There are 460
species of flowering plants recorded,
including 33 locally or regionally rare
species.
The ecosystems of the dunes have been and are being modified by human
activity. Four key examples of this are:
1) Pine plantations – past and present
2) Golf courses
3) Visitor pressure
4) Conservation of fixed dunes
1) Pine plantations
Ainsdale Sand Dunes National Nature Reserve (NNR) was purchased by English
Nature in 1965 to protect a nationally outstanding sand dune site. These dunes
were listed in 1915 by the eminent English naturalist Charles Rothschild in his
schedule of 'areas worthy of preservation', with Ainsdale dunes being regarded
as of 'primary importance' and of 'especial interest'. Subsequently a series of
national and international designations have confirmed its importance as a dune
system and wetland.
In the early twentieth century part of the future area of Ainsdale Sand Dunes
NNR was being planted up with pine trees as the northern extension of a wider
scheme across Formby Point. Planting was instigated by the landowner, Charles
Weld-Blundell, who had been inspired by the vast pine plantations created in Les
Landes in south-west France. His aim was to stabilise the dunes and turn the
'wasteland' into a more productive estate providing a timber crop, woodland
products and improved opportunities for agriculture and game. Shelter-belts of
Sea Buckthorn Hippophae rhamnoides were planted to protect the young pines.
The first pines were planted around 1900 and areas continued to be planted until
the 1960s.
Until recently the woodlands covered 176 ha, over a third of the Reserve area,
mostly of Corsican Pine Pinus nigra laricio. They were divided between a
generally poor quality 28 ha seaward frontal woodland and a more healthy 148 ha
landward rearward woodland. The woodlands today support an important
population of the Red Squirrel Sciurus vulgaris, now rare in England. The wet
slacks were generally not planted, although drainage ditches were put in to lower
the water table. (figures from Sefton Coast Forest Plan)
Pine plantation at Ainsdale causing changes in the natural dynamics of the dunes. This
results in the loss of dune habitat and associated species, and limits the ability of the
coastal system to respond to environmental change.
Once a woodland canopy is formed, the pine trees shade out the light from
the surface and no other plants are able to grow. Huge areas of natural
dune landscape with specialised sand dune plants and animals were lost in
this way. The water table drops and pine needles are deposited on the
surface and alter the structure and chemistry of the soil, creating very
different conditions from the original dunes. The needles are very acid (in
contrast to the basic sandy substrate that the pines were planted into) and
there is a very large accumulation of organic matter at the soil surface. In
the pine woodlands, the pine trees are often the only plant species present.
Surface of the dunes beneath
a pine plantation
Water plays an important role in the ecology of the dune area. Habitat
changes, as described, and drainage have led to a loss of wet slack habitat,
an important habitat for protected species such as the Natterjack Toad
Bufo calamita and Petalwort Petallophylum ralfsii and other scarce wetland
plants such as Grass-of-Parnassus Parnassia palustris and Marsh Helleborine
Epipactis palustris.
The rare natterjack toad lives on dune systems. The
combination of open water slacks, with shallow margins and nearby sandy areas
where it can burrow, is essential for breeding and winter survival. Lowland heaths
and dune systems in southern England provide a home for the sand lizard, another
rare inhabitant. They have adapted to the unstable habitat and need the subsoil
warmth to hatch their eggs.
The pine plantations have been colonised by Red Squirrels Sciurus vulgaris,
a rare, declining and protected species in Great Britain. The pine woodlands
at the rear of the Sefton Coast sand dune system are now welcomed as
feature of the local landscape and managed to maximise the conservation of
the Red Squirrels. On the frontal pine woodlands on Ainsdale Sand Dunes
National Nature Reserve there is a project to recreate the natural dune
landscape destroyed by the pine plantations.
Open Dune Restoration Project at Ainsdale
Sand Dune National Nature Reserve
Regeneration of sand dune vegetation in cleared pine plantation area.
The removal of the pine plantations on the frontal dunes will encourage
recolonisation by specialised plants such as Yellow Bartsia Parentucellia
viscosa and animals such as the protected Sand Lizard Lacerta agilis and
Natterjack Toad Bufo calamita and monitoring of the project shows that
this is already a success.
Yellow Bartsia, a rare plant of damp coastal grasslands. Since the
clearance of the pine plantations on the frontal dunes this plant has
recolonised the damp dune slack areas.
2) Golf Courses
Golf courses have been a feature of the landscape of the Sefton Coast for over
a century. The vast extent of sand dunes provided excellent terrain with
marvellous views and were judged to be as good as the sandy links of the east
coast of Scotland where the game first became popular. Golf courses today
occupy over a quarter of the dune area, 550 ha out of a total of some 2000 ha,
and much of this area includes the EU priority habitats of fixed dune and dune
heath, with associated species such as the protected Sand Lizard Lacerta agilis.
It is therefore essential, for the overall conservation of the dune system, that
golf course management is sympathetic to nature and that clubs help to
conserve their semi-natural duneland habitats.
The development of playing areas has obviously modified the natural duneland,
although on the Sefton Coast only about 25 per cent of any course area is
managed turf. Access is restricted to club members and visitors, and most
players try to keep out of the rough! The golf courses can therefore act as real
sanctuary areas for wildlife. Golf course management has had significant
benefits for nature. However, as on the nature reserves it became obvious in
the 1970s and 1980s that site quality was declining. This was particularly due to
invasion by scrub and rank grass which began to dominate the open dunes
following the outbreaks of myxomatosis in the mid 1950s. English Nature
responded to this problem by preparing site management plans for those courses
which included SSSIs (Royal Birkdale and Hesketh).
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Scrub clearance is necessary to improve the habitat for rare species
such as the Sand Lizard. South-facing banks are particularly important,
and a mosaic of bare sand, short and medium height grasses and herbs,
together with some low woody shrubs such as Creeping Willow Salix
repens, Gorse Ulex europaeus or Heather Calluna vulgaris , has been
found to be the optimal habitat (Cooke, 1991).
Cutting and over-turning turves, especially on south or south-east facing
slopes, to create bare sand patches on areas no larger than one metre
square, can provide valuable basking and egg-laying areas,
Mowing is an essential feature of golf course management which helps to
retain open dune grasslands in the semi-rough and rough. By slight
modifications to mowing regimes great benefits can be gained for
wildlife. For example, by varying the time of cutting or relaxing the
mowing regime, flowers can be allowed to set seed. Other areas can be
mown in alternate years or less frequently to open up the sward and to
provide invertebrates and small mammals with a suitable habitat mosaic.
Some courses may need to consider whether they are mowing too great
an area and too often. The area in front of the tee, or carry, may offer
opportunities for reduced mowing, whilst islands of rough on the fairway
could provide interesting hazards as well as valuable wildlife habitat.
3) Visitor pressure
Some five million people live within one hour’s drive of the Sefton Coast, putting
considerable pressure on this natural resource. Management of the NNR is
undertaken by English Nature, Visitor management on the NNR is part of a
wider zoning system used on the Sefton Coast as a whole. This identifies
honeypot areas such as Ainsdale beach, closed or permit-only sanctuary areas
such as the majority of the Ainsdale Sand Dunes NNR, together with a range of
partial access and less intensively used sites in between. This has the advantage
of encouraging the majority of people who come to the coast for the beach and
associated facilities to be concentrated in a few areas where intensive
management can take place to accommodate them. For example, facilities include
laid-out car parks, boardwalks to the beach, fencing to protect dune habitats,
trails, information boards, toilets and food and drink outlets. In this way the
integrity of the dune system is maintained and pressure is taken off important
habitats and species elsewhere on the coast. Ainsdale dunes are a good example
of an access gradient from high, at Shore Road beach access point in the north,
to low in the centre of the National Nature Reserve.
The quiet situation within the NNR provides a sanctuary for nature whilst
allowing access by permit. The limited access also made the establishment of
domestic grazing possible. With relatively low visitor numbers stock have not
been troubled. Only small interpretation signs, together with articles in the local
coastal magazine, guided walks and illustrated talks by the site manager have
been required. Access by permit-only visitors, or views from the three main
public permitted paths have generally been sufficient for those wishing to see
the NNR fixed dunes. The LNR is open access to public visitors and includes
several permitted paths as well as many informal footpaths particularly towards
the beach. The waymarked paths encourage people to remain on them, leaving
areas away from the path relatively undisturbed. In this way larger numbers of
visitors can casually visit the dunes without undue disturbance to wildlife.
However they are able to experience the wild nature of the site, the wildlife and
to gain greater understanding of the need to conserve such areas. Nearer the
beach access point, visitor access is more formal with beach car parking but
with information signs and facilities as expected at a busy resort beach. This is
supported by boardwalks and interpretation to reduce the impact to the dune
and beach area and natural processes, whilst informing and enabling inquisitive
visitors to discover more about the wildlife interest of the area.
4) Conservation of fixed dunes
The fixed dunes and associated species suffer from a number of factors
threatening to reduce their nature conservation value. The spread of scrub and
rank vegetation, in particular, leads to associated problems of soil development
and the desiccation of slacks.
Scrub invasion includes the establishment of tree and shrub species within the
open dune landscape, particularly non-natives such as pine (predominantly Pinus
nigra laricio), PoplarPopulus spp. and Sycamore Acer pseudoplatanus but also the
native Sea Buckthorn Hippophae rhamnoides and birches Betula spp. This leads
to the development of scrub woodland, a semi-natural habitat but one which
results in a loss of valuable open dune habitat. In addition, low woody shrubs,
such as Creeping Willow Salix repens, have grown tall and dense. Elsewhere an
increase in rank grasses and herbs particularly brambles Rubus spp. has
produced a dense undergrowth in areas not yet affected by scrub. These
changes have led to a reduction of bare sand and short turf and therefore the
high ground level temperature regimes which are a requirement of many dune
species. Outbreaks of myxomatosis since the mid 1950s have significantly
reduced rabbit numbers and have played a major role in these habitat changes.
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Scrub cutting and clearance
This allows light and warmth to reach the surface so colonisers can begin to
grow.
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Mowing
Mowing was used on the NNR in the 1980s to control the height and density of
Creeping Willow in dune slacks where it was rapidly overwhelming the short
botanically diverse dune turf.
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Turf-stripping and excavation
In the drought years of the mid 1970s many slacks in the NNR were scraped
to provide breeding pools for the Natterjack Toad.
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Grazing
For centuries rabbits had been an important influence on the ecology of the
Sefton dunes. Following the outbreaks of myxomatosis in the mid-1950s the
balance was lost and the dunes became overgrown with a loss in value for
nature conservation. Domestic grazing was re-introduced onto the Ainsdale
dunes by English Nature in 1990. It was previously practised on the rearward
dune areas along the coast until the late nineteenth century. Domestic
grazing has proved to be the most successful and appropriate form of
vegetation management. It has controlled target species such as Creeping
Willow, there has been an increase in species diversity with a corresponding
return to a low structural mosaic of vegetation with bare sand patches.
Domestic grazing has encouraged a resurgence in the rabbit population and
successfully maintained early successional stages in scrapes. Herdwick sheep
from the English Lake District have proved to be a particularly effective and
appropriate type of grazing stock with relatively low staff input and
maintenance costs.
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Blowouts
Blowouts create new sandy habitats within the fixed dunes including incipient
slacks, especially important for annual plants, specialised invertebrates,
Natterjack Toads and Sand Lizards. They are an important element of the
dynamic processes within the dune system. However where recreation causes
erosion, and particularly where property or infrastructure is threatened, dune
restoration techniques are used. Dune stabilisation works have been necessary
adjacent to the coastal road, near a holiday village and to prevent sand
encroachment onto the railway line.