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| Sefton Coast Partnership | Shoreline Management | Nature and Wildlife | Coastal Heritage | Visiting the Coast | Students and Teachers | Coastlines | |
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Summer 1997A Celebration of the DunesArticle By John HoustonLiving in Sefton it is all too easy to take our dunes for granted. Sand, to some people, is no more than a nuisance, but large dune systems, such as the Sefton Coast are extremely rare. Each major dune system in Britain is unique and will form part of a European series called the Natura 2000 network. But what makes dunes so special? On one hand, dunes are the most natural of all British habitats. To see new dunes forming on strandlines at the top of the beach is to witness nature in action. However, once dunes become ‘fixed’ by vegetation they, like heaths, downs and moors, only retain their open character by intervention, usually by grazing. They are commonly a habitat created by people over many centuries and are in their own right a cultural landscape of great significance. In early centuries the dunes would have been grazed by domestic livestock and only later did the dunes become rabbit warrens. The grazing and cultivation of the dunes kept the area open and allowed the survival of the characteristic animals and plants. Dunes, like heaths, survived because they had a function. However, throughout Britain, as ‘traditional’ land-uses broke up at the end of the nineteenth century so have many dune areas been swallowed up by development. What dunes remain are safeguarded primarily for their nature conservation value. Despite all its pressures and problems the Sefton dunes are the largest remaining dune system in England. What is a dune system? A dune system is more than just a pile of sand. It has its own domed water table, fed by rainwater, which drains off to seawards and landwards, it is a changing environment formed by the inter-actions of wind, rain and vegetation, it is a zone of extreme micro-climatic fluctuations, and is prone to both flooding and drought. Many animals and plants of the dunes are specialised and rare. Although they are one of the most complicated of all ecosystems, it is possible to divide dunes into three broad categories; fore dunes, yellow (or mobile) dunes and grey (or fixed) dunes. Interspersed between dune ridges are dune slacks where the wind has carved out a depression down to the watertable. The foredune zone is one of the most extreme habitats in Britain. Subject to salt spray, extreme temperatures, mobile sand and drought it is a zone of a few specialist species. The dune grasses Sand Couch, Sea Lyme and Marram are joined by plants such as Sea Holly, Sea Spurge, Sea Bindweed and Sea Rocket. These plants all have mechanisms for storing water and are, in effect, desert plants. This extreme environment is also the haunt of the Natterjack Toad which survives the heat of the day in its burrow only coming out at night to forage for its insect prey. The high mobile dunes, so characteristic of the coast, are formed by the marram grass which can tolerate burial by sand of up to 1 metre (3 feet) a year. A very important habitat is the wide transition zone between the mobile dunes and the fixed dunes. This is a zone where more plants and animals appear but importantly where there is still bare sand. Bare sand in the dune system, whether it is a bunker-like blowout or just a small scrape made by a rabbit, is essential to the survival of many species. Where there is bare ground, annual grasses such as Sand Cat's-Tail and Dune Fescue can seed. The Sand Lizard requires bare sand patches for egg-laying, and many species of bees, wasps and beetles also need sand patches. Plants of this zone include the grass Red Fescue, Sand Sedge, Creeping Dewberry, Wild Pansy and Hounds-Tongue. The most extensive dune habitat is the fixed dune zone. Even here though it is important to retain some areas of bare sand-tracks and footpaths can do this quite well. Fixed dunes are rolling landscape of short grass, low scrub and lichen covered dunes which without the continuation of grazing, by especially rabbits, will turn to tall scrub and dense grass. This is what has happened across most of the dune system since the myxomatosis outbreak in the 1950s to the overall detriment of the characteristic dune landscape and its wildlife. Open short-turf fixed dunes are a rich area for plants. Common species include the yellow Bird’s-Foot Trefoil, pink Restharrow, Lady’s Bedstraw, Common Centuary, Harebell, Carline Thistle and a host of dandelion-like flowers. Less common are Wild Thyme, Pyramidal Orchid and Bee Orchid. In patches of Creeping Willow you may also come across Round-Leaved Wintergreen, or the rare Dune Helleborine. Without natural or introduced grazing, dune scrub will eventually dominate the landscape and in time it will turn to woodland. Dune heath is another intermediate phase between open dunes and woodland, and occurs when leaching has left the soil more acidic. The final habitats to be considered here are the wet hollows and valleys, lying between the dune ridges, known as slacks. Dune slacks are formed by new dunes enclosing areas of beach, by tidal breaches or by wind action. Slacks are generally seasonally flooded and are the main breeding sites for the Natterjack Toad. Plants including the Early Marsh Orchid, Grass-of-Parnassus and Marsh Helleborine. Sand dunes are a rare and threatened habitat in Britain and Europe. Our challenge is to make sure that the Sefton dunes do not go the way many other dune systems and that in one hundred years and more there will still be a dune landscape supporting the species that were here before we arrived. Re-establishing and maintaining the sort of management that took place earlier this century, without trying to preserve the dune system in a time warp is probably the best chance for the future.
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