Afforestation
Of the total area of about 56,000 hectares (138,000 acres) of sand dune in Great Britain, it is estimated that about 4,048 hectares (10,000 acres) were planted in Britain from 1922 to 1952. These conifer plantations have many effects. Firstly, the shelter effect may extend in their lee over a distance equivalent to up to 25 times their height (Ranwell and Boar, 1986). Such shelter can allow the spread of scrub and trees which would be scorched in unprotected areas. Mature conifers of 25-30 years old provide a prolific seed source, seeding into slacks within the plantations as well as the open areas beyond. Trees lower the water table by their transpiration of soil water. Within the plantations, any remaining ground cover is shaded out, and the decaying needles acidify the soil, possibly destroying any seed bank of native dune species contained within it. When felled, there is little dormant vegetation in the way of seeds or rhizomes to cover the bare ground, so leaving it open to erosion. Measures to clear the forest and restore the nutrient-poor duneland vegetation can be expensive, as all tree stumps must be removed to prevent them rotting and enriching the nitrogen status of the soil.
There may also be a dilemma where the plantations have themselves developed a few interesting dependent plant or animal species, or where the trees are an accepted part of the local scenery, which people enjoy. Many dune forests were planted to reduce sand-blow inland, and this also may be seen as a possible threat if clearance is done.
Grazing
Grazing by rabbits, sheep and cattle has over the centuries been an important influence in the creation and maintenance of short-sward dune turf. In the past, it is likely that grazing was kept at sustainable levels by the knowledge of local people, and by the absence of machinery, fertilisers, wire fencing, piped water supplies and cheap winter feed. These modern changes permit over-grazing, often only for the benefit of short-term gain. In the past, rabbit populations were also managed by being enclosed in warrens, and by culling. This is in contrast to the greatly fluctuating rabbit populations in the decades since the introduction of myxomatosis.
Close grazing by sheep reduces the sand trapping ability of the dune grasses. Trampling and overgrazing leads to destruction of the sward and erosion of the thin soils and underlying sand. The areas where stock habitually rest become badly eroded.
Lack of grazing can be equally damaging as it allows rough grasses and scrub to invade. Experimental work has been done in recent years to investigate various grazing regimes and techniques suitable for managing sand dune reserves. Grazing is further discussed in the chapter on Vegetation Management.
Cultivation
The extent of cultivation is most serious in the shallow lee slopes of dunes in Scotland, called the machair. Cultivation is traditional, but recent use of fertiliser in place of seaweed has meant a loss of organic matter in these light and fragile soils. Elsewhere, cultivation is done on the landward margins of dune systems, which are mostly long altered from their natural state.
Housing
Housing and caravan development on sand dunes brings a host of problems. As well as the actual loss of sand dune area, there is increased recreational pressure on the remainder, both in total numbers and in out-of-season use. Associated development of roads and services means disturbance of the topography, soils, vegetation, natural drainage and water table. Plant species are introduced from gardens and garden rubbish, and the existence of homes in an unstable environment means increased pressure to undertake coastal defences, which in the long term disturb the natural cycle of coastal erosion and deposition (see below).
Industry
This brings many of the problems described above, with the added risk of major pollution, alteration of water table and the necessity for large-scale interference with natural processes to allow industry to function in an unstable environment. Fortunately, in Britain most sand dune areas are now protected against further housing or industrial development.
Military use
Emergency need, the perception of dunes as ‘waste’ land, and their coastal location has meant they have been heavily used by the military over many years. Some areas were just used in wartime, and have since been returned to public use. In some, such as Braunton Burrows, military use continues alongside management for nature conservation and public access. In others, particularly where airfields have been constructed, the military use is retained to the exclusion of others. Much military use involves large and heavy machinery which can greatly alter the dune habitat. Long-abandoned debris can still cause problems for dune managers by damaging mowing machinery and causing localised wind erosion. Military roads, now in public use, have resulted in the layout of access being haphazard rather than planned, and exacerbating management problems. Airstrips involve a major alteration to the topography and vegetation of a large area of duneland.
Recreation
This is possibly the most serious current threat to sand dunes, and the one most often tackled by conservation authorities and volunteers. The problems mainly arise from increased trampling destroying the dune vegetation, particularly on the foredunes, and the associated problems of car-parking, vandalism, camping, increased fire-risk, and direct damage to dune wildlife. Erosion is a natural process of dune systems, but that caused by public pressure greatly accelerates blowout formation in precisely those dunes where it can be tolerated least.
Examples are plentiful of sites where dune erosion requires public access control and stabilisation work. They range from intensively used nature reserves such as Ynyslas Dunes in Dyfed, Studland Heath in Dorset and Oxwich on the Gower Peninsula, where the damage is to important natural or semi-natural communities of plants and animals, to developed holiday areas such as Camber Sands, East Sussex, where damage to dunes is less significant than that caused by sand blow on poorly sited houses just back of the dunes. Each situation demands a different response, from severe access restrictions on the one hand to virtual remodelling of the dunes and their vegetation on the other.
An important concept in coastal management is that of ‘zonal use’ (McCarthy, 1970, p17). Fragile ecosystems such as dunes may be graded according to environmental qualities with associated appropriate usage levels. This suggests encouraging intensive recreation in areas which are already severely modified, such as Camber, which can be managed specifically for this, while prohibiting it as much as possible in relatively natural dune systems such as Ainsdale Sand Dunes, Merseyside. Large systems may be able to tolerate multiple-use zoning in space or time. For example, dunes which are beginning to erode can be temporarily fenced to let them recover while pressure is diverted to either side. Pony trekkers can be restricted to specially designed tracks, as at Oxwich, and ‘nests’ can be created to attract picnickers away from sensitive foredunes, as has been done at Gullane and elsewhere on the East Lothian coast. Access routes can be controlled across back-dune pastures, especially if these are used for golf courses, and car park spaces can be designed to limit peak-period use. Large systems, such as Studland, which already have high recreational use but which retain much wildlife interest, can be devoted to education along with recreation and conservation. Small, remote dune systems with climatically distinctive communities, as at Invernaver, Sutherland, are best left completely undeveloped for recreation if possible.
To successfully zone activities or intensities of use, one must know the ‘carrying capacity’ of an area. This can be defined as the level of use ‘just before the point where the species least resistant to trampling is degraded beyond its capacity to recover’ (Trew, 1973, p43). Carrying capacity is difficult to evaluate for dunes and is likely to vary according to local climate and exposure and the pattern of visitor use, but experience at one site on the west coast of Scotland (McCarthy, 1970, p16) suggests that vegetation cover, even in the rear dunes, is significantly damaged where a single track or footpath is used by more than two or three thousand people during the summer season. Dr William Band reports similar findings for established machair vegetation at Achmelvich, Sutherland. At Gibraltar Point, Lincolnshire, 7,500 people passing over the yellow dunes in a summer (Trew, 1973, p44) and 3,500-4,500 over the grey dunes (Schofield, 1967, p110) caused local exposure of soil and sand. Even where, as on the latter site, the dunes are little subject to wind erosion the habitat destruction can be considerable, especially for the invertebrate fauna which is often more severely affected than the dune plants themselves. Within dune systems, short turf areas are much more resistant to trampling than are dune heaths, which are in turn more resistant than the open marram or sea lyme dunes. But, according to Boorman and Fuller (1977), people tend to prefer these grassy areas in inverse ratio to their ability to withstand pressure. At Ynyslas NNR, pedestrian counters on the site have recorded a daily passage of 3,500 people during periods of July and August. Here, clearly, artificial path surfacing is essential to prevent serious erosion and habitat damage.
Golf courses
The light sandy soils, undulating terrain and coastal location have made sand dunes a favoured location for golf courses, and nearly every sand dune system has its quota. Indeed, the word ‘links’, a Scottish word for undulating sandy ground near the coast has become synonymous with golf courses. This recreational use may be seen as a mixed blessing. The restricted access means that trampling damage and erosion is controlled, and the management of roughs and fairways prevent scrub encroachment. The greens and fairways are largely altered by fertilising and re-seeding, but many of the roughs maintain a valuable duneland vegetation. It is ironic that some nature reserves are struggling with the problems of maintaining a short sward turf, whilst adjacent golf courses have no shortage of resources for this type of management.
A problem noted in Ranwell and Board (ITE, 1986) is that the siting of greens, tees and fairways near to the shore can restrict the options for coast management, for example by forcing protection of areas which are naturally eroding. On the other hand, the influential voice of the golfing fraternity can be the catalyst for action by local authorities and other agencies, for example to restore and replant eroded dunes where the sand is blowing onto adjacent greens. As in all situations where many agencies are involved in managing different sections of an integrated habitat, it is vital that there are good relations and co-operation between the various parties. In a recent example, a golf course management unwittingly destroyed a sand lizard colony by spraying a herbicide and replanting the site with introduced shrubs. However, it later co-operated with volunteers to try and recreate the habitat by transplanting turves of duneland vegetation back onto the site.
Wave erosion
Soft coasts are amongst the most naturally unstable environments in the world, and are constantly changing. In recent years, parts of the Merseyside sand dune system have eroded up to 9m (30′) in a single overnight storm, while parts of Studland dunes in Dorset are accreting at the rate of 3m (10′) every year. These changes are not of course a new phenomenon, but have been happening for thousands of years. What is new, and is increasing every year, is the length of coastline protected against erosion by groynes and sea walls, erected mostly to protect areas of housing and industrial development. This is reducing the capacity of the coast to erode and deposit, so that material which would previously have been eroded from one place and then washed up to replenish another is ‘locked up’ behind sea defences. Dredging offshore for sand and other sand winning operations have further decreased the natural ‘bank’ of sediments.
Thus not only has the area of sand dunes reduced from its extent say a century ago, but its capacity to restore and replenish itself has been lessened. This is an ever-decreasing cycle, as sand dunes themselves are the best form of coastal defence, being a wide natural buffer zone against flooding that has its own system of self-repair from revegetation. Thus loss means a greater need for man-made defences.
This all adds up to a great dilemma for sand dune managers, as in the natural state, erosion by the sea would be accepted as a process which keeps the whole system developing and changing. By stopping erosion and the formation of blowouts one is trying to fossilise a system which needs to be dynamic. On the other hand, the actual area of sand dune is so precious, and under threat from other factors, that it is difficult to stand by and not take action. The situation can resolve itself however, when sea erosion proves too powerful for any wave barriers which can be built. The recent publication by the Institute of Terrestrial Ecology (Ranwell and Boar, 1986), is aimed at giving guidance to engineers on the formation of dunes and their role in coastal defence. It advocates small-scale activities such as revegetating, access control fencing and so on as being more appropriate than massive engineering solutions.
Sand and shingle beaches
Beaches are often tempting sources of sand and gravel for local construction projects. Yet sand and gravel ‘winning’ almost always severely damages not only the beach itself but the higher land or dunes which back it. Quarrying of beach material lowers its level, allowing storm tides and waves to surge against the land behind. Dunes and soft coasts erode rapidly. Even relatively stable hard-rock coasts can be reactivated in this way, especially where beach material is taken from areas where natural replenishment is slow or absent. Steers (1969, p28) points out that in Scotland serious erosion is seldom a natural condition but is almost always the result of indiscriminate mining of beaches.
Where mining takes place not on the beach itself but on the land behind, restitution is often possible although prohibition is better. In East Lothian the council has required that operators cut away and roll up turf from the area to be mined, for reuse later, that they grade the excavated surface to resist wind erosion and that they replace the turf on the graded surface. This does nothing, of course, to preserve any particularly interesting plants which may grow in the quarried area. In the Shetlands, for example, entire populations of the oyster plant (Merfensio maritima) have been destroyed by mining.
A positive side of gravel winning is seen at Snettisham, Norfolk, where extensive shingle deposits were mined behind a narrow shoreline strand. Quarrying ceased when the great flood of 1953 overwhelmed this defence. Since then the Royal Society for the Protection of Birds has acquired the flooded pits and turned the area into an important freshwater wildfowl reserve.
Many beaches and dunes were used for military training during the Second World War, with effects which persisted for many years. Braunton Burrows National Nature Reserve, Devon, required extensive dune rehabilitation for this reason as well as because of increasing public pressure. The central part of the Burrows is still a military training area, but these days the MoD co-operates closely with the Nature Conservancy Council to minimise damage. Other legacies of the war are concrete anti-tank blocks and other beach defences. In places such as Gullane Dunes, East Lothian, these initiated severe local wind erosion before being removed. Simply burying them in place did no good because it further disrupted the beach and prevented the growth of vegetation where the tops lay just below the sand. At one stage, almost all the beaches in East Scotland had such defences. On the Suffolk coast they are still numerous, and range from metal ‘impalers’ to slowly disintegrating concrete pill-boxes. In some cases, it may be best to leave the major installations intact or to mound them over and provide interpretive signs so that their historical interest is not lost. Elsewhere destruction and removal is the only answer.
Pollution is particularly visible on recreational beaches and abatement efforts are often concentrated there even though adjacent sections of coastline may suffer just as much. In places, raw sewage is still pumped from poorly sited outfalls, causing widespread pollution for instance on the Glamorgan coast (Vale of Glamorgan Borough Council et al, 1975, p16). Oil is the chief pollutant, drifting in from spills to settle on beaches in sheets or tarry lumps. The actual damage caused by oil is probably more significant offshore, where it may cause disastrous bird kills (see Dune wildlife for coping with oiled birds), and on intertidal flats where it suffocates and poisons invertebrates when it settles to the bottom. But aesthetically it is beached oil which is most objectionable. An important side effect of strandline pollution, especially from oil, is that it tends to shift public pressure away from beaches to the sensitive foredunes, increasing the likelihood of serious erosion.
Once ashore, oil can be removed by burning, absorption into a wicking material such as straw, covering with powder, mechanical collection or dispersal by detergents. All of these are labour intensive and may require specially adapted equipment. For this reason and because oil removal (especially by detergents) may cause more damage than the oil itself, Warren Spring Laboratory (1972) recommends that oil be left in place in mud flats and salt marshes. On recreational beaches, lumps of oil can be drawn into rows by hand or preferably by tractor-drawn horticultural rakes, where it can be loaded into lorries for removal. Where the oil is in a film it is necessary to use detergent, but damage to the beach may be extensive so that only small sections should be cleaned for bathing and recreation. Elsewhere notices should be posted to warn the public of the pollution. Shingle beaches are particularly difficult to clean, and since to a great extent they are slowly self-cleaning due to wave action it is almost always best not to attempt to remove the oil.
Litter is a type of pollution which is more subject to abatement by volunteers. Not much can be done about rubbish dumped at sea, of course, other than to attempt to educate captains of ships using local ports, as is being done on the Glamorgan Heritage Coast (Vale of Glamorgan Borough Council et al, 1975, p16). Litter has its virtues: on the strandline it may help sand to accumulate by providing obstacles, and it has even been used to fill blowouts prior to reshaping of the sand surface. But in general it is best to keep litter under control. Many countryside managers feel that an area clear of litter encourages people to take their litter home, while an area which is badly littered acts as a magnet for yet more litter. Wardens and volunteers should, if possible, pick it up routinely rather than wait for the occasional litter drive which only has a temporary effect. Bins, if provided, must be emptied frequently so that they do not become overfull. Otherwise the wind just scatters the contents. Bins in exposed locations should have heavy, waterproof and wind-resistant lids. Where disposable bags are used, they often need to be fenced or clad against gulls or foxes which can rip them open.
Where litter drives are necessary, they are best done just before and again part-way through the holiday season, eg around Easter and in July. This way, you clear away the worst of the mess left by winter storms and keep the accumulation under control. Post-season drives do little good since the autumn gales are likely to bring in fresh supplies from the sea or elsewhere on the coast. Litter drives, whatever their amenity effect, are a good way to involve local people, especially children, in practical conservation. Initially, it may be best to go through schools or scout groups for recruits, but in the long run a corps of willing workers who can be called on when necessary will get more accomplished. Children often work better if they have an incentive. Pay them by the sackful, or at least give them something at the end of the season. Try a sponsored drive: you might even make a profit!
Vegetated shingle beaches are easily disturbed by trampling. Although people avoid walking on shingle when possible, they may have to cross it to reach the sea. Hewett (1973, p53) describes the impact of people on the vegetation of Chesil Beach, Dorset. Where there is easy access, there is little vegetation. Where access is restricted to a few distinct trackways, these stand out clearly as bare strips in the general mat of plant life. Where the beach is closed to the public, the vegetation is well developed, especially where it is manured by birds flying over the bank to reach the sanctuary of the Swannery.
Unvegetated beaches are relatively immune to direct recreational damage. But they do suffer from the increasing complexity of conflicting demands such as swimming, skin diving, spear fishing, boating and sand yachting. One solution is to zone beaches either in space or in time so that all interests may be catered for. This does not mean, of course, that all sites should admit jetties, hamburger stands, portaloos and amusement arcades. As public pressure increases, wardening becomes more vital. On nature reserves and heritage coasts where wardens are already hard pressed, volunteers can perform an important service during busier times of year. Newborough Warren. Ainsdale Sand Dunes and Winterton Dunes are among the National Nature Reserves where volunteer wardens are used. Besides general policing, volunteer wardens can mount the sort of intensive seasonal watch necessary, for example, for the protection of terns on many of their shoreline nesting sites. Local volunteers can often get the conservation message across to visitors as effectively as professional wardens, provided they are suitably trained in the art of gentle persuasion.
