135 - Dorset Heaths : Description

Physical and functional links to other National Character Areas

Lying centrally in the south of England and reaching the sea at and between Poole and Christchurch harbours, this area is framed by the heathland of the New Forest National Character Area (NCA) to the east, and to the south, west and north by the calcareous hills and downs of the South Purbeck NCA and the Dorset Downs and Cranborne Chase NCA.

The Dorset Heaths occur in a geological formation usually called the Poole Basin, a western part of the larger Hampshire Basin from which it is separated by the River Avon. Chalk forms the edge and bottom of the basin; Palaeogene (Tertiary) sands and clays lie within it and provide the substrate on which the various habitats in the Dorset heathlands have developed.

The most extensive deposit of these Palaeogene sands and clays are those of the Poole Formation. Around the edge of this area, between the heaths and the Chalk, is a belt, where Reading Beds and London Clays come to the surface. Here soils are still acid but are richer; heathland was never so dominant here. Overlying the sands of the Poole Formation are deposits of plateau and valley gravels.

The four principal rivers – the Avon, Stour, Piddle and Frome – flow first through the richer and more intensively used agricultural areas of the Dorset Downs and Cranborne Chase NCA and the Salisbury Plain and West Wiltshire Downs NCA before crossing and dividing the Poole Basin and eventually reaching the sea at Christchurch and Poole harbours. Much of the headwater and tributary flow derives from the chalk aquifer lying to the north and continuing at depth under much of the heathland. The water quality, particularly of the Frome and Piddle, has a direct impact on the quality of habitats within Poole Harbour.

Views across the area from the Purbeck Ridge – particularly near Ulwell, from Creech Barrow and from Whiteway Hill are spectacular. The landscape of the western heaths and the downs beyond is fully revealed. The rising Chalk geology largely surrounds and forms the backdrop to this NCA while also obstructing views to the Jurassic Coast. Seaward views can be gained, notably to the Isle of Wight from most of the open coast.

Across the valley of the River Avon, visible from St Catherine’s Hill, is another extensive area of heath in the New Forest.

A rich mosaic of semi-natural habitats and a coastal location make this an important landfall for species moving north from continental Europe, both on routine migration and as species distributions shift.

The main road and rail links run north-east-south-west from Southampton to the conurbation and then turn west (as the A35) towards Dorchester. The South West Coast Path National Trail terminates at the southern end of the Sandbanks ferry at the mouth of Poole Harbour, after running along Studland Beach.

Distinct areas

• Poole-Bournemouth-Christchurch conurbation.

The Dorset Heaths today

The Dorset Heaths NCA lies to the south of the Dorset Downs. To the centre of the area is Poole Harbour and to the south the prominent Chalk ridge of the Isle of Purbeck. To the east the area is bounded by the valley of the River Avon with the New Forest beyond. Much of the area takes the form of a shallow basin drained in the west by the rivers Piddle and Frome into Poole Harbour, and in the centre and east by the Stour and Avon into Christchurch Harbour.

The broad river valleys with fertile flood plains cut through the heathlands on their way to Poole and Christchurch harbours. Over winter and during the spring and autumn migration, these harbours are home to sometimes spectacular concentrations of wildfowl and wading birds. During the summer their sheltered nature makes them attractive venues for numerous watersports activities. Poole Harbour, especially on its south shore, and its smaller islands can feel remote, with the extensive mudflat, salt marsh and reedbed preventing ready physical access and so maintaining this sense of wildness.

Brownsea Island is owned by the National Trust and is a noted tourist destination, with visitors arriving by small ferry from both Poole and Sandbanks. Brownsea and the adjacent Furzey Island are home to one of only two surviving populations of red squirrel in southern England.

Pasture fields and flood meadows, with some arable use away from the riverside, occupy the valleys along with a scattering of small copses, riverside trees and occasional hedgerows. Extensive blocks of conifer plantation, mainly Corsican and Scots pine, on former heathland date from the early and mid-20th century, most notably at Wareham Forest in the west and Ringwood Forest in the north of the area. They remain dominant elements in the landscape, their dark, uniform character a stark contrast with the open, intricate and diverse areas of heath where gorse scrub and heather produce often bright colours and give texture to the heathland landscape and context to the summer birdsong and buzz of insects.

In the south-eastern part of the area is the heavily developed conurbation of Bournemouth, Christchurch and Poole, both a noted retirement location and, in the summer, a popular tourist destination. Tourist businesses are able to use the easy transport links with London, the kilometres of sandy beaches and one of the more benign UK microclimates. There are numerous hotels and guest houses. Despite the proximity to the rural parts of the area, access to high-quality greenspace can still be limited for residents of the conurbation, especially those without access to personal transport.

To the immediate north of the main conurbation a series of ‘dormitory’ towns (Upton, Broadstone, Corfe Mullen, Ferndown, Verwood and Three Legged Cross) of recent origin in their present form are scarcely distinguishable from towns of similar function elsewhere and contrast with the older cores of towns such as Wimborne Minster and Wareham.

Enclosure and reclamation of the heathlands for agriculture was still continuing in a piecemeal fashion until 1980. Boundaries variously include ditches, hedges and fences, and generally fail to provide a strong sense of pattern.

In the more rural areas, land-based commercial uses have sometimes struggled to remain competitive given the very poor nature of many of the soils. In the last two decades several dairy farms, for instance, have ceased milk production. In the same period, though, and as a direct result of conservation action, livestock grazing (beef cattle and ponies) has returned to many thousands of hectares of heathland, mostly ungrazed since about the 1930s. The continuation of this programme is providing a working example of landscape-scale conservation where adjacent, once discrete ‘sites’ are effectively extended and linked.

While livestock farming is the dominant agricultural use there are some areas of arable, often producing fodder crops such as maize, and more recently salad vegetable production.

Particularly to the north of the main conurbation some farmland is now used as pasture for ponies and horses that are kept for recreational use. In these areas livery is a growing business use, and modern field boundaries and small agricultural buildings are increasing in number and extent, often extending the feeling of urbanisation into open countryside.

Commercial forestry activity peaked in around the third quarter of the 20th century and is now declining as a combination of poor returns, pest and disease pressure, changed policy priorities and alternative (heathland conservation) uses for the very poor acid soils achieve more traction. In some areas this is substantially diversifying the views both from a distance and for those pursuing leisure and recreation activities within the old plantations. Large deciduous woodlands are scarce but where they do occur, primarily around the NCA’s margins, they tend to be oak dominated, with a hazel and/ or holly understory and a ground flora characteristic of acid soils.

Locally to Povington, Bovington and West Moors, military uses predominate. These areas are almost always closed to the public. Similarly there are extensive tracts of both active and worked-out quarry (sands, gravels and clays, notably ball clay) from which the public are generally excluded. Oil field infrastructure is concentrated around the south shore of Poole Harbour.

Outside the military ranges many of the larger blocks of heathland are now nature reserves (including six National Nature Reserves (NNRs)) or country parks and these, along with the Forestry Commission land, provide extensive opportunities for public access and engagement. These locations can be experienced in relative solitude on less busy days, enabling the visitor to gain a sense of the wilderness described so evocatively (‘Egdon’) by Thomas Hardy. The South West Coast Path has its eastern end at the entrance to Poole Harbour, and National Cycle Route 25 runs along the promenade at the foot of the continuous line of low cliffs from Christchurch to Poole.

Planning policy has tightly constrained development in and around many of the smaller villages, where a variety of vernacular styles still persist, presenting the visitor with an architecturally interesting selection of views. Research has demonstrated links between residential development and adverse impacts on adjacent heaths, which is now reflected in adopted planning policy.

The landscape through time

The Dorset Heaths NCA is underlain by gravels, sands, silts and subordinate clays deposited during the Palaeocene and Eocene Epochs (approximately 60-40 million years ago). The lowest Reading Formation (Palaeocene) forms a sandy, partly cemented gravel, which rests on the Upper Cretaceous Chalk, for example at Studland Bay. The relatively steep northerly dips of the rocks around Studland Bay decrease a short distance to the north, a result of the deformation that also formed the adjacent Purbeck Ridge and which took place during the period of the Alpine Orogeny. The Reading Formation is succeeded by the Eocene London Clay Formation (predominantly silt in this area). This in turn is overlain by the Bagshot Formation, which consists predominantly of sands but also contains lenses of clay containing important fossil flora. The youngest beds out-crop along the coast and belong to the Bournemouth Formation (Eocene). They consist predominantly of non-marine sediments, but a few marine horizons also occur. The outlier of younger beds on Creech Barrow Hill includes soft limestones and clays now assigned to the late Eocene.

The area is partly underlain by the Wytch Farm oil field, the largest onshore oil field in the UK, producing oil from Triassic and Lower Jurassic reservoirs deep below. The effects of the Quaternary ‘ice ages’ on the area over the last 2 million years have been to cover the Palaeocene and Eocene sediments with wide spreads and terraces of river gravels deposited by ancient river systems such as the Solent River. This river, now drowned by Southampton Water, once rose near Dartmoor and flowed eastward across the area before discharging into the English Channel.

Although poor in nutrients, the generally light soils of the area were easily cultivated with primitive tools and that, combined with a possibly sparser woodland cover and favourable southerly climate, probably led to this being one of the early locations for settled agriculture. Certainly pollen records suggest that by the Bronze Age much of the earlier tree cover had been heavily reduced and the landscape was essentially open and already heather dominated by around 4,000 BP.

Collections of bronze-age barrows, often on local high points in this already open landscape, attest to this early settlement. At Hengistbury Head, certainly by the Iron Age, a significant settlement was defended on the landward side by substantial earthworks or dykes. Evidence now suggests that for a period this and the adjacent Christchurch Harbour (giving access to the larger rivers of the Dorset Stour and Hampshire Avon) was a regionally important port through which trade with continental Europe was conducted.

The larger harbour of Poole also hosted an iron-age port, with quays on Green Island and the closely adjacent south shore of the harbour. Poole only superseded Christchurch in importance as a trading centre after the Roman invasion, at which point the port was at Hamworthy before moving to Wareham in Saxon times and only subsequently to its present location.

Roman transport infrastructure is still evident in places. An intensive Roman pottery industry was based, at least in part, on the Swineham peninsula east of Wareham. Black-burnished ware from here was traded across much of England and parts of the near continent. Pottery was to be a recurrent industrial theme, with production centred on Verwood from the medieval period and expanding to locations such as Brownsea Island, Poole and Sandford in Victorian times.

The Romano-British population in this corner of Dorset is thought to have withstood the Saxon advance for longer than most. Battery Banks to the west of Wareham, blocking the route along the high ground between the rivers Frome and Piddle, may have been a late line of defence, although its origins were probably earlier as a land demarcation. Eventually Wareham fell, and the Saxons subsequently reinforced the town with high earthbanks to the west, north and east which are still largely extant and are a notable feature of the local landscape.

While there are small settlements of some antiquity on the heaths, for example at Arne and Mannington, these are smaller and less interspersed with individual farmsteads than might be expected. This is probably a reflection of the poor productivity to be gleaned from the soils of the area, and those few settlements that did arise focused on pockets of better or more moisture-retentive soils. That occasional, now extinct, farmsteads did exist is in little doubt, as the remains of the banks that would have defined the extent of their in-bye land can still be traced in places. Often, though, the original dwellings have left less trace, probably because they were built of wood, cob and turf and have now completely returned to the land that originally yielded their construction materials. Towns and larger villages tended to be on the rivers at convenient crossing points, for example at Wimborne Minster, Wareham and Wool.

The basic pattern of both settlement and land use appears to have been well established before and little changed by the Norman Conquest. Subsequently some large landed estates became established, for example by the Drax and Bankes families centred on Charborough and Kingston Lacy respectively, the latter having fallen into the care of the National Trust in the 1980s.

The Dorset heathlands were the subject of a classic study by Norman Moore in the late 1950s, which documented their subsequent loss and fragmentation. He demonstrated that in the 17th century, heathland still stretched from the River Avon in the east to Dorchester in the west, broken only by the valleys of the rivers Stour, Piddle and Frome. This heathland landscape, the Egdon Heath of Thomas Hardy’s novels, was progressively reduced and fragmented by agricultural reclamation and more recently in the late 19th and 20th centuries by urbanisation, afforestation and large-scale mineral winning. Additionally, as commercial uses of the heathlands (such as grazing and turf cutting) declined, their tendency to succeed to scrub and woodland increased.

Surveys through the late 1900s recorded the continuing decline and fragmentation of the Dorset Heaths. These, combined with Moore’s cartographic studies, mean that the loss and fragmentation of the Dorset heathlands is one of the best documented, as well as one of the most dramatic examples of habitat decline in the UK.

The area was gradually connected to the rapidly developing railway network between 1847 and 1893, further assisting the process of urban expansion. Lieutenant-General Robert Baden-Powell held the first Boy Scout camp on Brownsea Island in 1907.

The World Wars saw the firm establishment of two major military ranges at Povington and Bovington, the home of the Royal Armoured Corps and a major cordite manufacturing facility at Holton Heath, part of which is now an NNR. Studland and Godlingston Heath (now an NNR) was used as a rehearsal site for the D-Day landings, including trials for duplex drive tanks, several of which still lie offshore as wrecks.

By the late 20th century, additional pressures included landfill (in many of the worked-out sand, gravel and clay pits); large-scale open cast extraction of both ball clay and aggregates; and industrial developments, including the construction of Dorset’s experimental nuclear power station on Winfrith Heath (now decommissioned) and the UK’s largest onshore oil field at Wytch Farm on the south shore of Poole Harbour.

In recent years, however, the decline of the heaths has largely halted and even started to reverse. Many of the remaining major blocks of heath have come into either public ownership or the care of conservation organisations and so most are now managed as nature reserves. A combination of changed ownership, changing public policy and associated changes in grant aid are leading to some significant areas being reverted from (mainly conifer) woodland or low-productivity pasture to heathland.