From a nature conservation point of view sand dunes, along with saltmarshes, are often considered to be relatively natural habitats with a high nature conservation value. This is usually assessed by reference to the vegetation. The dynamic nature of the dunes creates a landscape with a highly variable topography, which provides suitable habitats for a wide variety of specialists of both, plants and animals. Consequently, coastal landscapes should be maintained in a dynamic, migrating state, based on the significance of these features for ecological productivity, diversity of habitat and preservation of rare species (4)  (see: Natural ecosystems). Even in their early stages of development dunes host highly specialised habitats and quite a number of rare and declining species are restricted to them. However, dunes have been subject to considerable human impacts. These impacts have at a wide scale modified the nature of the vegetation, changed the geomorphological characteristics and even reduced massively the area of dune landscapes (2). Nowadays, the value of coastal dunes is increasingly recognised and many efforts are made with respect to conservation management (see: Vegetation management, Fauna reintroduction, Invasive species control, Artificial habitat development).
 

 1 – Natural ecosystems

The high nature conservation value of sand dunes is determined the geomorphological variety, the variety in habitats and plant communities and the rich flora and fauna which rely on them for part or all of their life-cycle. The area is very dynamic and varied due to various gradients, e.g. from salt to fresh water, waterlogged to arid ecosystems, alkaline to acid soils and pioneer to climax vegetation, mostly developed in very small scale patterns (see: Goeree, The Netherlands). Vegetation succession in dunes as a sequence from open mobile dunes to more stabilised types begins with the establishment of Ammophila arenaria and Elymus arenarius. The plants act as sand trapping systems which results in the development of foredunes. Dune grassland can establish as a more stable form where Ammophila arenaria becomes less frequent. This stage is followed by dune heath and scrubs, and as the oldest stage, dune woodland. Especially in very dynamic circumstances pioneer conditions with their pioneer communities can develop regularly. Fauna and flora are closely adapted to these extreme conditions and consequently a high biodiversity is found associated with rare species which often occur only in this habitat. Many rare and protected plant species also occur in nutrient-poor, moist to wet slacks, where the soil pH is buffered around neutral (see: dune slacks on the Wadden Sea Islands, The Netherlands). Dune slacks can occur where the water table is near the surface of the sand (see also Hydrology) (1, 2, 5).
 

 2 -  Vegetation management

Restoration projects regarding the vegetation can be divided into two practical measures. The first one concerns the re-introduction of extinct species by planting or sowing. This measure is critisised in some countries as it may change the gene pool of native species. The other one concerns management practices to reduce external nutrient inputs and acidification in dune-ecosystems and to open the canopy, like mowing, sod-removal, grazing or controlled burning. These latter measures facilitate a natural colonisation of species. In several dune areas biodiversity management consists of a mixture of the different treatments (e.g. Goeree, Kraansvlak, North-Holland Dune Reserve, the simulation model RESAM, Zwanenwater, all in The Netherlands; The Flemish Coast, Belgium). The introduction of large grazers may be seen as a reintroduction of former management, since extensive grazing was common in the dunes until the beginning of this century. Grazing by domestic livestock, rabbits (see: rabbit grazing in the Meijendel dunes, The Netherlands) and other herbivores has had a major influence on the vegetation of dunes throughout Europe and even determined the today’s landscape. Re-introduction of grazing can increase the diversity of plants if the right amount of animals is taken into account. In 1995, the DZH and the Wageningen Agricultural University launched a research programme to compare ungrazed and grazed parts of the Meijendel dunes, The Netherlands, with respect to vegetation development. An example of the effects of burning on dune heathland is given by a vegetation study in Hansted reserve, Denmark.
 

 3 – Fauna reintroduction

The decline of many rare species is often linked to alterations in the ecology of their habitats. The decline of the Natterjack toad (Bufo calamita) over the past 60 years is related to the encroachment of taller vegetation because of increased forestry activity and a reduction of grazing. The resulting shade is unfavourable for the Natterjack toad and, more importantly, encouraged the entry of its successful competitor, the Common toad (Bufo bufo) (5). In the Sefton Dunes the largest project in the UK Species Recovery Programme for the Habitats Directive-Annex IV species, the Natterjack Toad, took place. The project aims to re-establish the terrestrial habitat of the toad by a programme of scrub removal. This was followed up by sustainable management and work extended to other dune areas at risk. One way of achieving this aim is to establish a grazing regime and to prepare a good practice manual (see: www.seftoncoast.org.uk/). This example shows that fauna reintroduction has to be closely related to the restoration of the habitats.
 

4 - Invasive species control

The introduction of invasive species has often occured by the following reasons: erosion control (Hippophae rhamnoides), forestry (conifers, Australian eucalyptus) and amenity planting. Exotic plants not only compete with native species for light, water and other resources, they can even displace them. They can interfere with successional processes, harm animals including livestock, lower the water table (due to increased evapotranspiration), alter disturbance regimes and even modify geochemical processes (5). Also Australian acacia’s are often used for dune stabilization (Turkey). Acacia’s have the ability, like sea buckthorn, to form impenetrable thickets wich suppress and replace native vegetation. In the UK sea buckthorn has invaded the western coasts and causes great losses of natural vegetation. Sea buckthorn alters the nutrient status of the soil. These changes lead to an alteration in plant species. These findings are related to other invasive species on sand ecosystems. The Anholt Desert in Denmark had become  partly overgrown by self-sown mountain pine Pinus mugo. Because of that different management methods (e.g. branch crushing, felling with chain saw connected with chipping with or without removal of the timber, fine-cutting) were compared to determine the most useful one (see also: Flemish Coast, Belgium).
 In Spain much of the original  vegetation has been replaced by Pinus pinea. In Portugal open dune vegetations have been invaded by South-African various mesobryanthemun species.
 

5 - Artificial habitat development

Artificial creation of new dune habitats is often an attempt to compensate a loss or even an expected loss of habitats e.g. by coastal erosion. Knowledge of the biology and germination ecology of the species involved is crucial. In the National Park Hamburg Waddensea, Germany, this was practised because of the threatening loss of the breeding sanctuary Scharhoern. The environmental authority of Hamburg decided in 1989 to establish a new dune island by sand nourishment 1.5 km away in the southwest of Scharhoern: the artificial island Nigehoern. This project is declarated as a great success (3).

References:

1. Doing, H. (1997): Landscape ecology of the Dutch coast. In: García Novo, Crawford & Cruz Díaz Barradas (eds.): The ecology and conservation of European dunes. Universidad de Sevilla. (BCD97).
2. Doody (2000; in press): Coastal conservation and management. An ecological perspective.
3. Janke, K. (1996): Sieben Jahre Insel Nigehoern: Laesst sich die Aufspuelung einer Vogelschutzinsel mit den Naturschutzzielen des Nationalparkes Hamburgisches Wattenmeer vereinbaren?. Schriftenreihe Nationalpark Niedersaechsisches Wattenmeer. Band 2: S. 49-53. (31BCD97).
4. Nordstrom, K.F. (2000): Beaches and Dunes of Developed Coasts. Camebridge University Press. (PC2000a).
5. Packham, J.R. & A.J. Willis (1997): Ecology of Dunes, Salt Marsh and Shingle. Chapman & Hall. UK. (BC97).

Each case can be found via geographical maps and via thematical texts putting the cases in an order of six interesting topics:

	seashore dynamics
	sand mobility
	hydrology and water management
	conservation management
	management of forests
	management in relation to recreation and tourism