The shape of sand dunes, the open space they provide and the wildlife they support make the ecosystem an attractive place for humans to indulge in recreational activities such as visiting the beach and swimming, walking, pony-trekking, trail biking, bird watching, picnicking and kite-flying. Other human activities also affect the dune ecosystems. These include afforestation, intensive farming, reduction of sediment supply, tipping of domestic waste, reclamation for industry and the development of adjacent areas. Different activities cause different problems and kinds of damage to different parts of the dune ecosystem, for instance visitors to the beach who come to swim, sunbathe, walk, fly kites and picnic tend to see the embryo dunes as nice places to sit and walk over, which due to the lose nature of these dunes mean that they are easily destroyed. Mobile yellow dunes and fixed grey dunes are susceptible to damage from trampling but this actually has a different effect on them than the embryo dunes. Trampling on the more mature dunes helps remove the protective vegetation cover of these areas, exposing the soil which is then blown away to leave large semi-circular hollows known as blow-outs. These areas are reduced to lose sand, making colonisation by the plants that were in that area originally impossible. Before the blow-out can be re-established, marram and sand sedge must start the process of plant succession again. As a result, blow-outs can persist for a long time, unable to support much wildlife. Other activities which have the same effects as trampling mature dunes include trail biking and horse riding, both of which are popular as the shape of the dunes and the amount of open space lend themselves to these activities. People also leave litter around the dune complex, which is a hazard to animals and plants and causes them to die, which affects other parts of the ecosystem.
Other non-recreational human activities also affect the dunes. Afforestation has been initiated in some areas to prevent the movement of mobile sand but at the same time affected the ecosystems in the areas by disrupting the natural progression of vegetation. This destroys the unique properties of the ecosystem. Overgrazing by domestic stock reduces the vegetation cover of the area leaving it susceptible to blow-outs. Intensive farming either on the dunes or in the surrounding areas introduces fertilisers and drainage applications, which reduces the plant and animal diversity through soil compaction and nutrient enrichment. This again destroys the unique properties of the complex. Direct removal of sand from the beach or the dunes themselves reduces the sand available for the continuous evolution of the dune complex, impairing the ability to create and expand existing dunes and also directly destroying some of the sandier, less mature dunes. Other coastal stabilisation activities such as the addition of groynes further up the shoe affects the sediment supply available, which has the same affect, although rarely causes dunes to be destroyed. The tipping of domestic waste not only has a visual impact on the complex, but also kills vegetation by restricting light and air or by decaying to become poisonous to the plants or altering the pH of the soil. This reduces the vegetation cover leaving the area weakened and more likely to become a blow-out. Tipping of domestic waste also causes the addition of extra weight on the sand resulting in soil compaction making it harder for plants to grow. The dune ecosystem is completely destroyed by the reclamation of the land for industry. The dunes are deliberately destroyed and built, consequently eradicating all of the previous life that was supported on the dunes. The development of adjacent areas for uses such as golf courses and caravan sites also affects the dune ecosystems because of the use of herbicides and the manipulation of water supplies alter the conditions in which the vegetation on the dunes can grow. This may lead to the reduction in vegetation cover. The land is also sometimes utilised for military training which puts the land under stress from trampling and erosion by motorised traffic.
Methods used to protect the embryo and fore dune areas from human trampling include the erection of protective fencing, introduction of appropriate pathways, marram planting, signs, active wardening and the setting up of sand traps. The fencing prevents people from walking over the more unstable dunes, thus protecting them from damage by trampling. The introduction of pathways also encourages people to avoid walking over the dunes and stick to the pathways. Signs are also used to alert the public of the damage they cause by walking on the dune, hopefully encouraging them to stay away. Wardens patrolling the dunes can prevent people from walking over the dunes and damaging them. Marram grass planting and the construction of sand traps minimise the effects of the trampling.
Mobile yellow dunes can be protected in much the same way although in areas at high risk of developing into blow-out, protection groups such as Beachcare plant coastal plants. In areas where blow-outs have already occurred, repair of dunes typically involves temporary fencing of affected areas, preferably with explanatory notices to reduce any public indignation at such exclusion. Marram is primarily use for replanting, often with initial protection by laying brushwood over the site.
Attempts at restricting the development of land surrounding dune ecosystems are not often successful due to the increasing demand for the services created. However, it may not be able to remove the problem caused by development but measures can be taken to reduce the impacts of this. Soils and vegetation are monitored and appropriate procedures are taken to enable the vegetation progression to continue uninterrupted.
Reduction of sediment supply can be addressed by protection policies that prevent sand being removed from the beaches and dunes due to their protected status', for example Oxwich Dunes (South Wales) are now a National Nature Reserve. Unfortunately it is difficult to reduce the impacts of stabilisation works elsewhere along the coast which interrupt the supply of beach material.
Intensive farming in areas surrounding sand dunes is encouraged to be replaced by organic farming or other methods which create less of an impact on the dune ecosystems.
Afforestation is no longer practised along dune complexes as the ecological importance of leaving the dunes to develop naturally has been realised. The impacts of previous processes have been lessened by leaving the dunes to re-establish a natural pattern of vegetation progression.
Tipping of domestic waste is now prohibited due to active preservation of the dune ecosystems, however this does not stop litter being dumped there by tourists. Attempts to prevent this come mainly in the form of signs and wardening to alert the public of the fragile state of the ecosystem and the damage caused by improper waste disposal.
When dune complexes are used by the military, most of the land is used resulting in all parts of the dune ecosystem being damaged. The damage is corrected by dune reconstruction. An example of dune reconstruction is at Gullane, East Lothian. Here the dune system was used for military vehicle training during World War II. A dune ridge was constructed along the seaward boundary of the area, planted with Lyme Grass (Leymus arenarius) on the seaward side and Marram (Ammophila arenaria) on the landward side. This enclosed a large, relatively dry hollow, effectively a dune slack, which in the early 1980s was still substantially open sand. Marram was planted for stabilisation and the area has become well vegetated. A tarmac path runs down from a carpark to the popular public beach and this is lined with planted Sea Buckthorn which, due to its thorns, has helped keep the public out of the area during recolonisation.
As public awareness of the importance of these ecosystems increases, the dune complexes are becoming increasingly more protected. It is important however to try and find a balance between the preservation of the dunes and allowing people access to the area. An example of a well managed sand dune ecosystem is Studland Bay. This can be seen as a successful attempt to manage the impact of humans on an ecosystem, and it should be noted that management itself has an impact, all be it a comparatively positive one. This is the nearest to a perfect solution in the management of sand dune ecosystems and it gives an exemplary outline to how all sand dune complexes should be managed to reduce the impacts of humans on dune ecosystems.
Bibliography
16-19 Core Geography (Michael Naish & Sue Warn) - Longman Group 1994
Changing Environments (Michael Naish & Sue Warn) - Pearson Education 2000
http://www.purchon.com/ecology/wales.htm
http://www-biol.paisley.ac.uk/bioref/Habitats/dunes2.html
http://www.ew.govt.nz/ourenvironment/coasts/coastalecosystems/dunes.htm
http://ourworld.cs.com/gdstrudley/geography/ecosys.htm