Habitats & Conservation
Slapton Ley National Nature Reserve covers an area of 214.7 hectares; the nature reserve supports a diverse range of habitats including ‘coastal vegetated shingle’, woodland, reedbed, open water and mixed farmland. The principal habitats are more specifically described here
Coastal Vegetated Shingle
Coastal vegetated shingle is a relatively rare habitat. Worldwide, shingle (sediment of size ranging from 2-200mm) is almost exclusive to Northwest Europe, Japan and New Zealand but in the UK as much as 30% of the coastline is shingle. In most cases, this takes the form of shingle beaches but in some cases, like Slapton Ley, the shingle is extensive and undisturbed enough that it becomes colonised by vegetation. This vegetated coastal shingle is fairly rare, even in the UK, and so the plants and insects that characterise the habitat of high conservation importance. The main threat to this habitat and its wildlife is human disturbance; removal of the sediment for industry has damaged many shingle habitats and erosion by walkers and vehicles remains a problem here.
At Slapton Ley, the shingle forms a ridge between the sea and the ley; this ‘shingle ridge’ formation has three zones: the seaward-facing beach, the ridge crest and the ‘backslope’, which faces the ley. Each of these zones has a distinctive habitat character and associated wildlife. The beach is the most inhospitable environment as it is closest to the sea and regularly pummelled by waves; this fact in itself would not preclude the development of vegetation as there are many so-called ‘pioneer’ species of plant that specialise in this kind of habitat, however, the intense use of the beach for recreation means that in order to see this vegetation you have to go to the lesser-used areas such as Strete Gate. Here you will find the best examples of shingle vegetation, such as yellow horned-poppy and sea kale.
The next zone is the ridge crest. This is the top of the ridge where the road is located. It is largely protected from the high wave energy of the beach and so some soil has managed to develop, however, its vegetation is still characterised by ‘halophytic’ or salt-resistant species and those that can withstand drought from the freely draining soils. These include viper’s bugloss, sea mayweed and thrift. Here, the main threats are from erosion by walkers. The situation used to be far worse, when the ridge became a car park for holiday-makers during the summer months but the statutory protection afforded by its designation as a Site of Special Scientific Interest (SSSI) has since brought this under control.
The third zone is the ‘backslope’: the slope that faces towards the ley. It is protected from the sea by the ridge and has less pressure from erosion; as a result, it has more developed, less specialised vegetation – although halophytes like sea radish are still found. The conservation issues around this habitat come are associated with loss of biodiversity from under-management and scrub encroachment. The grassland of the backslope used to contain greater species richness, which was maintained by grazing of livestock. Following the cessation of farming, the grassland has become ‘rank’: long and tussocky with a dense thatch of accumulated vegetation. This ‘rank grassland’ is important for mammals and birds of prey but has lower species richness and is dominated by a handful of vigorous plants. There are areas that have become dense scrub, dominated by gorse and blackthorn; this scrub is valuable to some species such as dormice and Cetti’s warbler, but in order to maintain a mosaic of habitat types that will maximise biodiversity, it needs to be controlled. So habitat management of the backslope includes cutting area of grassland and clearing areas of scrub.
There is a wide variety of woodland habitats across the reserve that are managed in different ways and attract distinct wildlife. The majority of woodland habitat comprises Slapton Wood and France Wood. Slapton Wood is classified as Ancient Woodland as it has been continuously wooded for more than 400 years; France Wood on the other hand is a younger ‘secondary woodland’ dating back to the 19th century. Their species composition is similar, containing oak, sweet chestnut, beech, sycamore and ash with an understory of hazel and holly. Other small areas of woodland include Southgrounds Copse; this a small area of woodland managed by coppicing: a traditional practise of harvesting wood which benefits wildlife by opening up the woodland floor to sunlight, encouraging plants like violets and primrose, which in turn attract invertebrates such as butterflies and hoverflies. As they regrow, birds and dormice nest in the dense vegetation. There is also a significant area of willow carr woodland, which grows on wet, boggy ground at the edge of the ley and into the river valley.
Open water and reedbed
Slapton Ley ('Ley' is a local term for 'lake') is the largest natural body of freshwater in South-western England. The 70-hectare expanse of open water and its associated reedbed is used by a wide variety of plants and animals; otters can be seed on the ley, as well as great crested grebes, gadwall, water rail and occasionally wintering bittern. There is also a diverse invertebrate fauna, which includes water scorpions, water stick insects and dragonfly nymphs. The best way of experiencing the birds of the ley is by coming along to one of our free events, such as our Dawn Chorus or Birds of Slapton Ley guided walks; or discover the underwater invertebrates at our family-friendly What Lurks Beneath events. Click here for details.
However, Slapton Ley is a ‘eutrophic’ water body, which means it has high concentrations of nutrients, such as nitrates and phosphates. There are numerous sources of nutrient pollution, including sewage works and poorly maintained septic tanks (‘point source’) and artificial fertilisers, slurry and manure from farms within the catchment (‘diffuse’).
A major impact of eutrophication is the periodic occurrence of algal blooms; an algal bloom is the rapid growth of a microorganism call ‘cyanobacteria’ (not actually and algae). The water becomes thick with the bright green or turquoise bacteria, which can be toxic to animals and prevents important plants from growing. The plants that grow in the water are called ‘macrophytes’ and are and an important part of the ecosystem, upon which insects, fish, mammals and birds rely so as a result, algal blooms have a significant impact on the ecosystem. They don’t happen every year but usually during very hot, dry summers when there’s little dilution of flushing-through of the water.
There is a lot being done to tackle the problem of water pollution in the catchment of Slapton Ley: Environment Agency monitor the discharge of sewage works and septic tanks and have the power to prosecute if laws are broken. Natural England work with farmers to help them reduce their impact with the help of government subsidies and further technical advice is provided to farmers by organisations like the Westcountry Rivers Trust and South Devon AONB. There is evidence that this is having a positive impact as the rates of nitrates are falling year-on-year.
Some of the most important wildlife of Devon exists on farmland and relies on sensitively managed pasture and arable land. We manage about 18 acres (7.5ha) of mixed farmland for wildlife, in particular, cirl buntings, which are rare birds that are confined to South Devon and a few sites in Cornwall, where they have been recently reintroduced. They like a combination of south-facing grassland, arable fields and large hedges. They feed on insects in the summer then they are rearing their young and cereal seed in the winter, while they need large hedges to nest safely. This kind of management also benefits a variety of other wildlife, including butterflies, linnets, horseshoe bats and dormice.