Coastal vegetative shingle
What is it?
Shingle is defined as sediment with particle sizes in the range 2-200 mm. It is a globally restricted coastal sediment type with few occurrences outside North West Europe, Japan and New Zealand. Shingle beaches are widely distributed round the coast of the UK, where they develop in high-energy environments. In England and Wales it is estimated that 30% of the coastline is fringed by shingle. However, most of this consists of simple fringing beaches within the reach of storm waves, where the shingle remains mobile and vegetation is restricted to temporary and mobile strand-line communities.
Shingle structures take the form either of spits, barriers or barrier islands formed by longshore drift, or of cuspate forelands where a series of parallel ridges piles up against the coastline. Some shingle bars formed in early post-glacial times are now partly covered by sand dunes as a result of rising sea levels leading to increased deposition of sand.
The origin of coastal shingle varies according to location. In southern England, much of it is composed of flint eroded out of chalk cliffs. Shingle deposits of Ice Age origin lying on the seabed may be reworked by wave action and redeposited or moved by longshore drift along the coast. In northern and western Britain, shingle may derive from deposits transported to the coast by rivers or glacial out-wash. Shingle structures are of geomorphological interest.
The vegetation communities of shingle features depend on the amount of finer materials mixed in with the shingle, and on the hydrological regime. The classic pioneer species on the seaward edge include sea kale Crambe maritima, sea pea, Lathyrus japonicus, Babington's orache, Atriplex glabriuscula, sea beet, Beta vulgaris, and sea campion Silene uniflora; such species can withstand exposure to salt spray and some degree of burial or erosion.
Further from the shore, where conditions are more stable, more mixed communities develop, leading to mature grassland, lowland heath, moss and lichen communities, or even scrub. Some of these communities appear to be specific to shingle, and some are known only from Dungeness. On the parallel ridges of cuspate forelands, patterned vegetation develops, due to the differing particle size and hydrology. Some shingle sites contain natural hollows that develop wetland communities, and similar vegetation may develop as a result of gravel extraction.
Shingle structures may support breeding birds, including gulls, waders and terns. Diverse invertebrate communities are found on coastal shingle, with some species restricted to shingle habitats.
Shingle structures that are sufficiently stable to support perennial vegetation are a comparatively rare feature, even in the UK.
The situation in the South East
|Extent in England||5,000 ha
|Extent in the SE region|| app. 1,500 ha
|Percentage UK resource in the SE||30%|
|Extent covered by SSSI designation|
Dungeness, in southern England, is by far the largest site, with over 2,000 ha of shingle – there are only five other structures over 100 ha in extent in the UK. The main concentrations of vegetated shingle occur in East Anglia and on the English Channel coast, in North East Scotland, and in North West England and South West Scotland. The Welsh coast has a number of small sites.
Rate of Change
|County||1998 extent (ha)||2008 extent (ha)|
|Isle of Wight||5||5|
|Kent||1810||Data to be added|
The main threats to this habitat are:
- Sediment supply: The health and ongoing development of a shingle feature depend on a continuing supply of shingle. This may occur sporadically as a response to storm events rather than continuously. It is frequently lacking owing to the interruption of coastal processes by: coast defence structures, offshore aggregate extraction, or artificial redistribution of material within the site (eg. Dungeness). Attempts have been made to rectify the situation by mechanical re-profiling, which is likely to fail in the long run because it does not address the lack of new material, or by beach recharge.
- Natural mobility: Shingle features are rarely stable in the long term. Many structures exhibit continuous longshore drift, and ridges lying parallel to the shoreline tend to be rolled over towards the land by wave action in storm events. This movement has a knock-on effect on low-lying habitats behind the shingle. Movement is likely to be accelerated by climate change resulting in sea level rise and increased storminess.
- Exploitation: Shingle structures have been regarded as a convenient source of aggregates, and have been subject to varying degrees of extraction resulting in severe alteration of morphology and vegetation (eg. Dungeness and Spey Bay) or almost total destruction of major parts of the feature (eg. Rye Harbour). Industrial plant, defence infrastructure and even housing have been built on shingle structures (eg. Dungeness, Orfordness, Spey Bay), destroying vegetation and ridge morphology. At Dungeness water is abstracted from the groundwater system; there is some evidence of drought stress on the vegetation, but it is difficult to distinguish the effects of water abstraction from those of gravel extraction.
- Access: Shingle vegetation is fragile; the wear and tear caused by access on foot, and particularly by vehicles, has damaged many sites. The causes include military use, vehicle access to beaches by fishermen, and recreational use. Such disturbance can also affect breeding birds.
- Grazing: In a few cases areas of shingle were traditionally grazed, but this management has now largely ceased, leading to domination by willow carr on wetlands and changes to vegetation structure. The impacts of removal of grazing on breeding birds and other shingle species are not fully understood.
Vision for Coastal Vegetative Shingle
The South East Biodiversity Forum’s vision for this habitat is that there should be:
- No further loss of existing habitat
- Good management, including visitor management, on all extant sites
- No damage to site integrity from activities arising outside the sites, eg. inadequately managed public access
- Re-creation of vegetated coastal shingle on appropriate sites to restore some past losses, including the linking up of fragmented sites
- Greater public appreciation of vegetated coastal shingle and their specialist wildlife, including greater awareness of the impacts of human pressures, such as dog-walking, mountain-biking, dumping of waste
- Creation of alternative green space around important vegetated coastal shingle under pressure for increasing new housing
How we can deliver this vision
- MoD Integrated Land Management Plans (www.defence-estates.mod.uk/conservation/2_biodiversity.php)
- Provision of land management advice by statutory (Natural England) and non-statutory agencies (NGOs)
- Agreements under Higher Level Stewardship
- Project funding (SITA Trust, WREN etc)
- Site management plans
- Minerals after-use (http://www.afterminerals.com/)
- Land purchase/management agreements by NGOs
- River restoration linked to Water Framework Directive Programme of measures
- Catchment Sensitive Farming tackling diffuse pollution issues