GUIDANCE FOR THE MANAGEMENT OF COASTAL VEGETATED SHINGLE

Introduction

Coastal vegetated shingle is a term used to describe a range of geomorphological structures defined by the size range of the pebbles that make them up. When conditions are favourable for plant growth the surface can support significant areas of vegetation. Included in this guide are both shingle beaches, which may occur as narrow, essentially linear features and beaches and structures, which can be large features in the coastal landscape. The extent to which vegetation becomes established on the shingle surface helps to determine the nature conservation value and in the context of this guide, the approach to management and restoration.

Coastal vegetated shingle is recognised as an internationally important, rare and threatened habitat. The world distribution is relatively restricted, being mostly confined to the glaciated parts of the northern and southern hemispheres. It is scarce in Europe with the UK (especially Great Britain) supporting a high proportion of the European resource. Elsewhere, coastal shingle has few occurrences outside Japan and New Zealand. Coastal vegetated shingle is listed as a priority habitat in the UK Biodiversity Action Plan (BAP) and supports 9 BAP priority species. The vegetation is characterised by specialised plants that have adapted to survive in harsh coastal conditions where lack of fresh water and nutrients are compounded by fierce winds and impact by waves. Shingle habitats are also particularly important for invertebrates and for some breeding and roosting birds.

A number of case studies (sites in England visited in late 2002) have been used to augment the information. The geomorphology and vegetation is also described in more detailed than in the guide to "Coastal Habitat Restoration, towards good practice". The coastal vegetated shingle guide adopts the same format as the more general guide, information is provided under the following headings:

Pressures

The structure and function is extremely important to the survival of both shingle beaches and structures and their associated plant and animal communities. They are also crucial factors in sustaining the coastal defence capability. Pressures include shingle extraction and artificial 'protection' by structures, nourishment and/or reprofiling to help sustain their coastal defence function especially in south and southeast England. These actions are usually designed to retain the shingle beach in situ. However, in these situations continued reprofiling, restrictions on sediment supply (whether natural or artificial) and room in which natural movement can take place, prevents the natural plant and animal communities typical of these areas from developing. At the same time the cumulative effects of extraction, development and coastal defence structures can deplete and restrict sediment availability further exacerbating erosional trends. Offshore aggregate extraction is also a significant issue.

Shingle structures are especially vulnerable to exploitation and disturbance. The destruction of the surface shingle through aggregate extraction (including the excavation for sand and gravel) is the principle cause of loss. This has lead to major change in the biological and geomorphological interest. Habitat loss has also occurred as a result of building houses, power stations and other infrastructure developments, which also destroys the surface shingle. There are a further set of pressures from other activities including recreational use.

States and values

Shingle beaches and structures are important geomorphological features, support rare plant and animal communities and create conditions where other habitats, notably saltmarshes and saline lagoons can develop. They can also often provide significant coastal defences. The states described in this guide are defined largely by their degree of stability:

• State 1 - eroding shingle beaches, where material is moved by tidal and wave action. The overall trend for this state is erosional with a net loss of material from the system;
• State 2 - stable or accreting forms tend to be associated with shingle structures, though beaches are included where there is no net loss of material from the system;
• State 3 - Over time the surface shingle becomes colonised by relatively stable vegetation a wide range of plants and animals.

The resource can have considerable economic value for building material (sand and gravel) and some of the larger deposits have been extensively exploited. The disturbance associated with this exploitation leads to a loss of conservation interest as the surface shingle is destroyed leading to two further damaged states:

• State 4 - the depth of excavation is at or above the water table (note this state in not identified as a separate state in the more general guide);
• State 5 - excavation below the water table. Although this can result in an increase in open water (gravel pits) and the development of a sometimes considerable bird interest, this is different from the original and sometimes unique vegetation and associated animals which it replaces.

Management of vegetation, visitors and coastal defence

Shingle beaches are by their nature resilient to disturbance caused by natural events. They are formed and respond to changes in wave climate and storms as the material moves along the shore by long-shore drift. Any vegetation which develops tends to be short-lived or adapted to change and exposure to saltspray. Managing specific seral stages of development (important to other coastal habitats) through grazing or other forms of intervention is generally not appropriate. Controlling alien plants and the need to protect ground-nesting birds are special issues

Shingle structures also have a much more restricted range of traditional forms of management than those associated with other coastal habitats, namely sea cliffs, sand dunes, grazing marsh and saltmarshes (dealt with in the Guide "Coastal Habitat Restoration, towards good practice"). Agricultural use is limited, with grazing restricted to a few larger more mature sites, which support closed grassland or heathland communities soil conservation may be an issue. Recreational use is an important issue.

Coastal defence is also an important management issue for both beaches and structures. The types of coastal defence, structures and maintenance operations are well known. The operations associated with coastal defence can have a serious impact on coastal vegetated shingle at some sites and mitigation management may be an important issue.

Restoring shingle beaches

Restoration of shingle beaches is considered from two perspectives, namely:

1. Coastal defence, increasing stability Erosional to Accretional (State 1 to State 2);
2. Nature conservation, increasing instability Accretional to Erosional (State 2 to State 1)

The first of these is largely concerned with maintaining the beach or structure in its current position. Thus the control or prevention of movement is seen as a key requirement when undertaking restoration activity usually requiring continued maintenance, which usually prevents anything other than the most ephemeral communities to develop.

The second may seem to be in conflict with the first. However, from a nature conservation perspective the dynamic of a shingle beach may be important as part of a natural defence and can help heal areas where human exploitation has destroyed conservation value. There is a paradox here due to the stabilising effect of artificial structures, at least in the short to medium term.

Restoring the surface and vegetation on shingle structures

Restoring existing mature, stable, vegetated shingle surfaces (State 4 to State 3) will be required where the surface shingle has been excavated or otherwise disturbed. The type of restoration will depend to some extent on whether the vegetation is near the water table and remains damp, or not. Excavations, which result in open water gravel pits (State 5) are not considered to be re-creatable in the context of restoring coastal vegetated shingle.

Monitoring

The guide provides some information on general monitoring methods as well as more specific actions and needs. The more general guidance is based on the approach being adopted in the UK by the government conservation agencies who are producing a Common Standards Monitoring (CSM) programme for designated sites, under the direction of the Joint Nature Conservation Committee. More information is provided on a range of specific methodologies or for particular elements within the ecosystem.

Legislation and funding sources

In order to aid the process of decision-making in relation to management and restoration policy information, information is also provided on some of the more relevant legislation. Maps show the distribution and location of the main shingle sites in Great Britain (most of them designated as Sites of Special Scientific Interest). Further information is provided on potential funding sources.

Publications:

• Key documents: Unlike sand dunes and saltmarshes there are not management guides for coastal vegetated shingle. The most recent relevant publication provides a synthesis of current knowledge of the resource from an European Union for Coastal Conservation seminar (Packham et al. 2001), chapters 8 and 9 (Doody 2001) deals with Shingle beaches and structures and Dungeness respectively. Note: These and other key reading are listed and the Report, upon which this electronic Guide is based includes a full bibliography of key texts and shingle related publications;
• Guides: Coastal Vegetated Shingle is one of seven habitats included in the Guide entitled "Coastal Habitat Restoration, towards good practice". The West Sussex Vegetated Shingle Project has produced a good practice guide for coastal defence engineers and others working on shingle beaches to minimise impact to the wildlife. A full-colour, waterproof ID card has also been produced to help on-site workers to identify the various vegetated shingle communities. Both the Good Practice Guide and the ID Cards are available on request from the projectofficer@pebbledash.org.uk. CIRIA are also responsible for producing some more general guides;
• Web sites: BERM - Beach Erosion in the Rives Manche, An interim report, final report and a bilingual summary of the final report are available to download at: http://www.geog.sussex.ac.uk/BERM/.

Key References

Doody, J.P. 2001. Coastal Conservation and Management: an Ecological Perspective. Kluwer, Academic Publishers, Boston, USA, 306 pp. Conservation Biology Series, 13

Packham, J.R., Randall, R.E., Barnes, R.S.K. & Neal, A. 2001. Ecology & Geomorphology of Coastal Shingle. Westbury Academic and Scientific Publishing, 459 pp.