How to Rewild

Dunes and Vegetated Shingle

Habitat Management Plan

HomeGuides

Dunes and Vegetated Shingle
Habitat Guide

Contents

Sand dunes make up about 5% of our coastline in England (where data is readily available), while about 2% is shingle, and very little of this is vegetated. But these zones are more than just diversity-supporting habitats – they are also an essential part of our coastal infrastructure. With climate change causing sea levels to rise, shingle and sand are being eroded away, but they’re still the front line of our defences against the sea in many cases, forming natural berms that hold back tides and storm surges.

These can be pristine habitats with little human influence, but in many, if not most places, coastal vegetated shingle and sand dunes have high levels of disturbance. They’re the gateway to the beach for many people – an ecosystem that is experienced only in passing. These habitats are also fairly unique in the terrestrial realm as they naturally shift either towards *or* away from scrub and woodland, depending on the extent of coastal erosion.

Sub Habitats

At the rear of sandy beaches, where the input of sediment exceeds the output, it will be deposited in the form of a rolling dune system. Over time it stabilises, with the system becoming a mosaic of grassland, ponds, scrub and wet woodland.

At the rear of shingle beaches, where the input of sediment exceeds the output, it will be deposited in the form of a system of berms. Over time these are stabilised by low vegetation growth, and may eventually succeed to woodland. In some cases, shingle systems also exist inland.

Value

Sand Dunes generally develop on wider, exposed beaches, where dry sand is swept up above the high water mark by wind, then colonised by Marram Grass. After this, the system evolves from shifting, embryonic dunes into a more mature system, with low ‘dune slacks’ that often contain wetlands. These habitats may be colonised over time by scrub and then woodland, stabilising the sand, while depositing layers of new organic matter. Depending on the state of the dune system, different communities of organisms will be present, and some of these habitats can be extremely biodiverse. The dune slacks at Braunton Burrows are allegedly the most diverse wildflower meadows in the country with over 400 species of plant.

However, the diversity of dunes varies a huge amount between systems, depending on human disturbance, erosion, management regimes, and the presence or absence of invasive species of plant. These may be low value lumps of sand with sparse Marram cover, or high value ecosystems with a mosaic of meadows, ponds, scrub, open sand and closed woodland. In either case, their value also comes from their coastal protection. As ‘natural sandbags’, dunes prevent tidal surges and spring tides from flooding coastal properties. In many cases, they may have been artificially stabilised with defences, ‘nourished’ through dredging of offshore waters, or engineered to make them stronger.

Shingle is less common than sand dunes, not just in the UK, but worldwide – in fact, northwest Europe contains a significant share of this habitat. Rarer still is vegetated shingle – like sand dunes, shingle banks may shift over time, but eventually they can stabilise, with the help of vegetation. But this vegetation may naturally be damaged in storms, and rising sea levels increases the height of these storm waves over time. This sensitive habitat, often destroyed by human activities, from gravel extraction to trampling, is home to a specialised community of invertebrates and plants which are adapted to the harsh, drought-like conditions.

Shoreline Cliffs and Slopes
Erosion of cliff faces is an essential part of the sediment cycle, which creates new material that replenishes sand dunes and shingle systems nearby.

Protect

Sand Dunes aren’t just one habitat, but a spectrum of different communities at various stages of succession from open beach to closed woodland. Typical management encourages the formation of this mosaic habitat and protects it by removing scrub and woodland where these late successional stages threaten the earlier, specialist communities of plants and invertebrates, which are unique to dune habitat. This usually involves scrub management (i.e. not just brushcutting, but also scraping off topsoil) and coppicing or removal of woodland.

Bare patches of sand are valuable habitats for a variety of invertebrate and reptile species like Sand Lizard, while shallow depressions in sandy areas may create pools suitable for threatened amphibians, including the rare Natterjack Toad. These bare sandy patches occur naturally in wild dune systems – particularly those disturbed by large herbivores. At Kraansvlak in the Netherlands, Bison create wallows in coastal sand dunes and disturb the dune system, maintaining a constantly-evolving habitat. At Braunton Burrows in Devon, military exercises are used for the same purpose, creating a variety of states of succession across the site. In the absence of Bison or the army, a combination of cattle and manual interventions – coppicing, scrub clearance and soil disturbance – can mimic this activity.

Dune systems are often colonised by invasive non-native plants – particularly Sycamore and Japanese Rose (Rosa rugosa). These species swamp natural vegetation, reducing biodiversity and rapidly shifting embryonic dunes towards more mature systems. Invasive species removal work is an essential part of an effective dune management plan. However, while government documents and leading charities claim that Sea Buckthorn is non-native outside of the East of England, our own scientific research and consultation with experts uncovered that this is probably not the case. This species likely used to be widespread across most of the British Isles, and it may have been eradicated from the West coast due to shifting sea levels and a high density of woodland in the early Holocene.

Sea Buckthorn does tend to dominate dune systems, but this seems to be due to the absence of a balanced guild of wild herbivores, not its questionably native status. As with any form of scrub, in the absence of Bison and similarly-sized herbivores, it will slowly encroach across the system. However, Sea Buckthorn has value for biodiversity, supporting invertebrates like the Oak Eggar moth caterpillar, providing a perch, refuge and/or food for birds including Stonechat, Starling, Wheatear and Fieldfare, and creating shade that may be used by reptiles and amphibians in the harsh heat of a dune system. The plant also aids in stabilisation of dunes which are increasingly subject to erosion due to sea level rise.

Both Sand Dunes and Vegetated Shingle are affected by human disturbance – dog walking can cause significant issues for ground-nesting birds (and reptiles in dunes). In dunes, this includes Skylark and Ringed Plover, while on shingle, terns and gulls are more common. The physical trampling of vegetation can tear apart root structures over time, which hold together both shingle and sand. Marram Grass is quite resilient to this, and recovers easily when areas are temporarily fenced off (typically with chestnut palings). But on Shingle, many species are not evolved to cope with trampling at all, and high disturbance can easily destroy entire areas of vegetation. In fact, vehicle disturbance to shingle systems can cause visible damage that may last for hundreds of years.

While sandy shorelines tend to be threatened by erosion hotspots created by coastal defence structures upwind, the erosion of these same structures (especially riprap) may actually nourish shingle beaches, though the overall impact may still be a sediment deficit if shingle-rich cliffs are protected. Offshore dredging can also decrease the availability of new sediment inputs. Vegetated shingle has historically been threatened by gravel extraction, development and vehicle access, though most British habitats are now protected against these threats.

Dunes and Vegetated Shingle
Creating designated paths through fragile sand dune systems can reduce erosion in busy areas, increasing the resilience of the system to winter storms

Restore

On Sand Dunes, in the absence of Sea Buckthorn, hard engineering work may be used to protect and stabilise dunes. However, this is more effective in the absence of coastal protection upwind, which blocks sediment inputs. Groynes, sandbags and even dead Christmas trees may be used to shore-up dunes in decline, but none of these can protect the system if sea levels continue to rise and sediment inputs continue to remain low or fall (see e.g. Dawlish Warren). Dredging of sand for extraction is therefore also a threat to sand dunes.

The ecology of dunes is ever-shifting, but we’re now missing many wild herbivores; particularly the ‘mega-herbivores’ which would have engineered these habitats in the past. In their place, we often have rabbits that create a very different ecosystem. This may be biodiverse in places, but scrub tends to encroach over time, and large patches of bare sand are often missing. The wildest dune systems in Europe are those managed by a combination of different herbivores, including Bison. On very large reserves, Bison are an option, but they need huge exclusion zones due to interacting poorly with dogs.

In the absence of Bison, we can use a combination of Highland Cattle and Exmoor Ponies to recreate a healthier system. In larger herds, bull cattle will dig ‘bull pits’ when competing with each other for females during the mating season. This clears areas down to bare sand, naturally creating this valuable habitat, but also comes with the risk of high testosterone animals in a public area. Cattle push through scrub, keeping the area open, while the ponies keep grassland trimmed to a short sward, maintaining this habitat and preventing further scrub encroachment. Stocking levels are key to sand dune conservation – too low and scrub will encroach; too high and erosion could threaten the survival of this sensitive coastal barrier.

Artificial materials and coastal defences are often used to reinforce dune systems. Most of these are dependent on a stable supply of sediment into the system, and a net sediment deficit will eventually lead to their loss. Wooden groynes can mitigate some wave strength and trap drifting beach sand, creating a wider shoreline. This protects dunes against the ‘coastal squeeze’ that climate change is causing. But without sediment input, groynes can’t trap sand that doesn’t exist, and their linear structure doesn’t protect dunes in storms that occur at a right angle to the line of the beach.

Hard engineering work to restore dunes and reinforce them with massive geotextile sandbags (‘Geotubes’) took place at Dawlish Warren in the 2010s. But, in a system which was already suffering from a sediment deficit and rising waters, this work may have undermined the dunes. Marram grass failed to establish effectively in areas where the work had taken place, and the bags were soon exposed all along the coast, creating an eyesore at this major tourist destination. While many dune systems, like Dawlish Warren, are being eroded, there are places in Britain, like Weston-super-Mare, where sand dunes continue to grow over time due to a net sediment input.

On sensitive Vegetated Shingle habitats, given the impacts of human activity, experts advise that the best course of action in these areas is to leave them to recover on their own. Any kind of mechanical input can destroy the root system of plants and shift the fragile berms, so removal of invasive species is the most intensive activity that is typically undertaken here. If the water table has been degraded by draining and abstraction, these systems should be restored to a natural state where possible.

Contents