• Home   /  
  • Archive by category "1"

Isle Of Purbeck Dorset Case Study

  1. Geographical description
  2. Main soil threat
  3. Natural environment
  4. Drivers and pressures
  5. Status of soil threat
  6. WOCAT maps
  7. Administrative and socio-economic setting
  8. Management options
  9. Stakeholder involvement
  10. References

 

Details about the RECARE experiment in the United Kingdom can be found here 

Geographical description

The Isle of Purbeck is not a true island but a peninsula of ~200 km2 on the south coast of England. It lies to the West of The New Forest National Park and is in the County of Dorset. It has a mild temperate Atlantic climate with mean annual rainfall of around 777 mm.y-1 and an average temperature of around 11oC. Purbeck is a complex multifunctional, multi-land-use landscape with a range of competing pressures from arable farming, high and low intensity livestock grazing, touristic land use with quarrying and military areas all expecting their share of the lands' ecosystem services. The soils are highly contrasting in pH, both naturally and through anthropogenic manipulation and are generally sandy to sandy loams, derived from a complex underlying geology.

 Location and Digital Elevation Model (DEM) of the Isle of Purbeck (Source: SRTM).

Main soil threat

The Isle of Purbeck is a multifunctional landscape with enormous pressure placed on soil resources due to the contrasting and competing land uses, past and present. The major soil threat here is a loss of soil biological function, linked to depleted biodiversity due to persistent physical and chemical manipulation of the land. Degradation has been caused by various means, most insidious is the large scale manipulation of soil pH for competing agriculture uses which has led to heavy lime (and historic marl) application for arable land use, and subsequent intense sulphur application to reverse such previous alkalinisation. The latter was done to provide low intensity grazing land, in keeping with the traditional and historic land uses of the area. This has led to a landscape with soil pH ranging from 3 to 8.5 often through artificial manipulation. The treatment of the soil in such a way has led to a clear loss in microbiological function where we have seen microbial biomass decline by one-half and biodiversity has been reduced by over two-thirds and where plant-microbe symbionts are absent or of the wrong type. The landscape has also been subject to other degrading activities including extensive recreational use in some areas, military disturbance (including the use of high powered ordnance) and quarrying. These have all contributed to a loss of biodiversity in the soil to varying degrees.

Other soil threats
The acidification has caused significant loss of microbial diversity and plant life leading to areas subject to soil erosion which can occasionally leads to complete top soil loss. The acidification has also led to the mobilisation of toxic metal cations in soils and run-off which provides additional threats to the effected sites and the surrounding environment (Green et al., 2007). Quarrying and military land uses alone have led to degraded soils that are poorly productive and fertile for reasons beyond biodiversity loss. Unrelated directly to biodiversity effects, but likely affecting biodiversity, the Case Study also includes areas that display significant soil erosion, as well as land degraded and threatened by coastal erosion and cliff failures.

 

The challenge is to rejuvenate the critical biodiversity in the soil after disturbance and this requires a detailed assessment of the functions that have been lost (nutrient cycling, symbionts, decomposition, pathogen control and so on). The relationship between diversity and function is not well established in soils generally; partly, at least, due to the large component of functional redundancy, and this will need to be assessed for our soils. The reintroduction of lacking diversity may require interventions such as inoculation, modified tillage, modified nutrient management and phytoremediation, depending on the initial results of the study.

 

Natural Environment

Geology & Soils

Geology of the Isle of Purbeck is shown in the table belwo. Table belwo shows the area coverage of geological deposits, indicating that Tertiary sand, Jurassic limestone and clay, and drift over Mesozoic and Tertiary clay and loam constitute almost 60% of the study area. There is also an abundance of chalk deposits, which contribute to intensive quarrying activity in the area.

Geology of the study area. Source: NSRI (2001)

 

GeologyArea [ha]% Area

Cumulative

Area %

Tertiary sand5,425.0426.01 
Jurassic limestone and clay3,378.3116.1942.20
Drift over Mesozoic and Tertiary clay and loam3,341.6116.0258.22
Mesozoic and Tertiary sand and loam1,744.168.3666.58
Chalk1,239.965.9472.53
Sandy drift1,214.275.8278.35
Jurassic and Cretaceous clay660.973.1781.52
River alluvium over peat626.273.0084.52
Other3,229.6315.48100.00
TOTAL20,860.22100.00100.00

Distribution of main geological deposits within the Isle of Purbeck

 

The soils in the Isle of Purbeck are highly contrasting in pH, both naturally and through anthropogenic manipulation and are generally sandy to sandy loams, derived from a complex underlying geology. They are dominated by sandy and clayey soils oftentimes situated over chalk and limestone deposits. The following figure and table provide detailed information on the soils of the area. These soils are characterized by high organic carbon contents, with soils containing up to 2% of organic carbon constituting a relatively small portion of the area (see below).

Soil associations of the case study area at mapping scale of 1:250 000. Explanations of soil association symbols are given below. Source: NSRI (2001)

 

Soil AssociationDominant soil description Area [ha]% Area

Cumulative

Area %

641bdeep sandy5,425.0426.01 
343dshallow clay over limestone3,378.3116.1942.20
711gseasonally wet loam to clayey over shale3,341.6116.0258.22
571gloam over sandstone1,744.168.3666.58
341shallow silty over chalk1,221.655.8672.44
861aseasonally wet deep sand1,214.275.8278.26
712bseasonally wet deep clay660.973.1781.43
813aseasonally wet deep clay over peat626.273.0084.43
Other 3,247.9415.58100.00
TOTALS20,860.22100.00100.00100.00

Main soil associations of Isle of Purbeck listed in descending area coverage order. The table provides further explanation to soil association symbols(above)

 

Average organic carbon contents in the top 30 cm layer of soil. Source: NSRI (2001).

 

 

Land Use

Land use of the Isle of Purbeck is dominated by pastures, followed by agricultural land and heathland (below).

 

Major land use classes within the Isle of Purbeck case study area derived from the CORINE 2006 land use/land cover map (EEA, 2014). The black lines indicate the location of parishes. The protected areas comprise several datasets (see text for details) and were compiled from data obtained from the British Environment Agency (EA, 2014)

 

 

A fair part of the area is covered with either coniferous or deciduous woodland. Approximately a quarter of the area is under some form of protection, and a large part of Lulworth parishes is owned by the Ministry of Defence. Settlements are mostly discontinuous, with the largest concentration around the town of Swanage. The landscape has also been subjected to other degrading activities including extensive recreational use in some areas, military disturbance (including the use of high powered ordnance) and quarrying.

 

Image of Landscape Matrix in the Isle of Purbeck

 

Climate

The Case Study has a mild temperate Atlantic climate with mean annual rainfall of around 777 mm y-1 and an average temperature of around 11 oC.

 

Left: Average annual; right: mean monthly precipitation and temperature at the Isle of Purbeck.

 

Drivers and pressures

The drivers to soil biodiversity decline are many and include many soil threat considered in RECARE. Many of the drivers related to the either the overuse of land (by people or animals) or changes in land management due to policies enacted at EU, National and regional levels. The major threats include: soil compaction on arable, woodland and pasture land, footpath erosion and compaction, soil sealing, coastal erosion, acidification of chalk hills by gorse, quarrying and salt blast (windblown salt from the sea). All of these impact on soil biodiversity.

 

Status of soil threat

Preliminary data indicate a significant decline in parts of the microbial community. Preliminary analysis suggests significant shits in microbial function as a result of acidification.

ThreatExisting solutionPotential solution
Soil compaction on arable landCultivation technique, proper timings, subsoiling, tillage techniqueDrainage
Soil compaction on pasture land  
Soil compaction in woodlandUsing horses instead of heavy machinery during forestry work to reduce damage to the forest floor 
Footpath erosion and compaction Changing access policy, re-routing, building stone steps
Soil sealing Preventing further residential developments, houses built at lower densities, gardens rather than concrete, proportional approach to development
Intensive agricultureIncentivising less intensive agriculture, a farmers cooperative promoting local productsPrecision agriculture, common agricultural policy, people prepare to pay more for food
Coastal erosionSoil nails, netting, drainage to prevent slippage 
Acidification of chalk hills by gorseClearing of the gorse, grazing, burning 
QuarryingRestoration programmes dictated by planning policy 
Preventing soil development by restoring heathland Ceasing the restoration
Wind erosion on arable land Plant trees around field, increase vegetation cover with grass
Salt blast  
Cultural ignorance Education, the Common Agricultural Policy
Proximity of large urban area  

List of soil threats identified including existing management options and potential future solutions

 

 WOCAT Maps

Maps on the current state of land use, soil degradation and soil conservation in the case study area have been produced using the WOCAT (World Overview of Conservation Approaches and Technologies) methodology

The steps of this process are as follows:

1) The area to be mapped is divided into distinctive land use systems (LUS).
2) The team gathers the necessary data on soil degradation and conservation for each LUS using a standardised questionnaire, in close consultation with local land users, and supported where possible by remote sensing or field data.
3) For each LUS, the soil degradation type, extent, degree, impact on ecosystem services, direct and indirect causes of degradation, as well as all soil conservation practices, are determined.
4) Once collected, the data is entered in the on-line WOCAT-QM Mapping Database from which various maps can be generated.

Following the principles of all WOCAT questionnaires, the collected data are largely qualitative, based on expert opinion and consultation of land users. This allows a rapid and broad spatial assessment of soil degradation and conservation/SLM, including information on the causes and impacts of degradation and soil conservation on ecosystem services.

More details about the methodology used to produce these maps and their interpretation can be found here.

 

Land Use (click on maps to expand)

 Degradation

The degree of degradation reflects the intensity of the degradation process, whilst the rate of degradation indicates the trend of degradation over a recent period of time (approximately 10 years).

Conservation measures

The "effectiveness" of conservation is defined in terms of how much it reduces the degree of degradation, or how well it is preventing degradation. The Effectiveness trend indicates whether over time a technology has increased in effectiveness.

Administrative and socio-economic setting

Protected areas depicted in figure above are under a combination of several forms of protection. These are RAMSAR sites, Special Sites of Scientific Interest (SSSI), Special Areas of Conservation (SAC), and Special Protection Areas (SPA). RAMSAR sites are dedicated to protection of wetlands and waterfowl habitats. SSSIs aim at protection of sites hosting wildlife and notable natural features. SACs are areas that offer protection to wildlife and habitats as an initiative of an EU directive, and SPAs are dedicated to conservation of wild birds.

 Population in the Purbeck District (left) and GDP per capita trends (right)

 

Management options

The challenge here is to rejuvenate the critical biodiversity in the soil after disturbance and this requires a detailed assessment of the functions that have been lost (nutrient cycling, symbionts, decomposition, pathogen control and so on). Generally, the relationship between diversity and function is not well established in soils, partly, due to the large component of functional redundancy. This relationship will need to be assessed for the soils of the Case Study. The reintroduction of lacking diversity may require interventions such as inoculation, modified tillage, modified nutrient management and phytoremediation depending on the initial results of the study.

 

Stakeholder involvement

Relevant end-users and local stakeholder groups include;

• Farmers, land owner and land managers
• Natural England
• Ministry of Defence
• Dorset County Council
• National Trust

Learning platforms for Stakeholders will be established in order to facilitate knowledge exchange and mutual learning between the different participants from local to national level. Open field days will be held alongside a short course in remedial measures. Potential regulation options will be jointly agreed with stakeholders in the course of our wider consultation and policies at Cranfield University.

 

References

EA, 2014. http://www.geostore.com/environment-agency/WebStore?xml=environment-agency/xml/ogcDataDownload.xml

EEA, 2014. http://www.eea.europa.eu/data-and-maps/data/clc-2006-vector-data-version-3

NSRI, 2001. The National Soil Map of England and Wales 1:250,000 scale. National Soil Resources Institute, Cranfield University, UK. http://www.landis.org.uk/data/natmap.cfm

The Isle of Purbeck is a peninsula in Dorset, England. It is bordered by water on three sides: the English Channel to the south and east, where steep cliffs fall to the sea; and by the marshy lands of the River Frome and Poole Harbour to the north. Its western boundary is less well defined, with some medieval sources placing it at Flower's Barrow above Worbarrow Bay.[1] According to writer and broadcaster Ralph Wightman, Purbeck "is only an island if you accept the barren heaths between Arish Mell and Wareham as cutting off this corner of Dorset as effectively as the sea."[2] The most southerly point is St Alban's Head (archaically St. Aldhelm's Head). Its coastline is suffering from erosion.

The whole of the Isle of Purbeck lies within the local government district of Purbeck, which is named after it. However the district extends significantly further north and west than the traditional boundary of the Isle of Purbeck along the River Frome.

In terms of natural landscape areas, the southern part of the Isle of Purbeck and the coastal strip as far as Ringstead Bay in the west, have been designated as National Character Area 136 - South Purbeck by Natural England. To the north are the Dorset Heaths and to the west, the Weymouth Lowlands.[3]

Geology[edit]

See also: Geology of Dorset

The geology of the Isle is complex. It has a discordant coastline along the east and concordant coastline along the south. The northern part is Eoceneclay (Barton Beds), including significant deposits of Purbeck Ball Clay. Where the land rises to the sea there are several parallel strata of Jurassic rocks, including Portland limestone and the Purbeck beds. The latter include Purbeck Marble, a particularly hard limestone that can be polished (though mineralogically, it is not marble). A ridge of Cretaceouschalk runs along the peninsula creating the Purbeck Hills, part of the Southern EnglandChalk Formation that includes Salisbury Plain, the Dorset Downs and the Isle of Wight. The cliffs here are some of the most spectacular in England, and of great geological interest, both for the rock types and variety of landforms, notably Lulworth Cove and Durdle Door, and the coast is part of the Jurassic CoastWorld Heritage Site because of the unique geology.

In the past quarrying of limestone was particularly concentrated around the western side of Swanage, the villages of Worth Matravers and Langton Matravers, and the cliffs along the coast between Swanage and St. Aldhelm's Head. The "caves" at Tilly Whim are former quarries, and Dancing Ledge, Seacombe and Winspit are other cliff-edge quarries. Stone was removed from the cliff quarries either by sea, or using horse carts to transport large blocks to Swanage. Many of England's most famous cathedrals are adorned with Purbeck marble, and much of London was rebuilt in Portland and Purbeck stone after the Great Fire of London.

By contrast, the principal ball clay workings were in the area between Corfe Castle and Wareham. Originally the clay was taken by pack horse to wharves on the River Frome and the south side of Poole Harbour. However, in the first half of the 19th century the pack horses were replaced by horse-drawn tramways.[4] With the coming of the railway from Wareham to Swanage, most ball clay was dispatched by rail, often to the Potteries district of Staffordshire.

Quarrying still takes place on Purbeck, with both Purbeck Ball Clay and limestones being transported from the area by road. There are now no functioning quarries of Purbeck Marble. The Purbeck Mineral and Mining Museum displays an exhibition about ball clays, mining and the associated narrow gauge railways.

Wild flowers[edit]

The isle has the highest number of species of native and anciently introduced wild flowers of any area of comparable size in Britain.[5] This is largely due to the varied geology. The species most frequently sought is Early Spider Orchid (Ophrys sphegodes), which in Britain, is most common on Purbeck. Nearly 50,000 flowering spikes were counted in 2009. Late April is the best time, and the largest population is usually in the field to the west of Dancing Ledge. Smaller numbers can be seen on a shorter walk in Durlston Country Park. This orchid is the logo of the Dorset Wildlife Trust. Cowslip meadows (Primula veris and Primula deorum) are at their best shortly afterwards and Durlston Country Park has several large ones.

In early May several woods have carpets of Wild Garlic (Allium ursinum). King's Wood and Studland Wood, both owned by the National Trust, are good examples. At around the same time and later some Downs have carpets of yellow Horseshoe Vetch (Hippocrepis comosa) and blue Chalk Milkwort (Polygala calcarea). In late May the field near Old Harry Rocks has a carpet of yellow Kidney Vetch (Anthyllis vulneraria).

Blue and white flowers of Sheep's bit (Jasione montana) and pink and flowers of Sea Bindweed (Calystegia soldanella) lend colour to Studland dunes in June. Both Heath Spotted Orchid (Dactylorhiza maculata) and Southern Marsh Orchid (Dactylorhiza praetermissa) are frequent on Corfe Common that month, and Harebells (Campanula rotundifolia) and Purple Betony (Stachys officinalis) flowers add colour to the Common in July.

Dorset Heath (Erica ciliaris), the county flower, can be found in July and August in large numbers, especially on and around Hartland Moor, in damper parts of the heathland. Bog Asphodel (Narthecium ossifragum) gives displays of yellow flowers there in early July. Marsh Gentian (Gentiana pneumonanthe) is found less frequently in similar areas from mid August to mid September.[5]

Human history[edit]

A number of Romano-British sites have been discovered and studied on the Isle of Purbeck, including a villa at Bucknowle Farm near Corfe Castle, excavated between 1976 and 1991.[6] The Kimmeridge shale of the isle was worked extensively during the Roman period, into jewellery, decorative panels and furniture.[7]

At the extreme southern tip of Purbeck is St Aldhelm's Chapel which is Norman work but built on a Pre-Conquest Christian site marked with a circular earthwork and some graves. In 1957 the body of a 13th-century woman was found buried NNE of the chapel which suggests there may have been a hermitage in the area. In 2000 the whole chapel site was declared a Scheduled Ancient Monument. The precise function of the chapel building is disputed with suggestions that it may have been a religious retreat, a chantry for the souls of sailors who had drowned off St Aldhelm's Head or even a lighthouse or warning bell to warn sailors. Victorian restoration work of the chapel found signs that a beacon may have adorned the roof. The present cross on the roof is Victorian.

The town of Wareham retains its Saxon earth embankment wall and its churches have Saxon origins. One of these, St Martins-on-the-Walls was built in 1030 and today contains traces of medieval and later wall paintings.

At Corfe Castle village is the great castle which gives the village its modern name. The castle commands the strategic gap in the Purbeck Ridge. The present castle dates from after the Conquest of 1066 but this may replace Saxon work as the village was the place where Saxon King Edward the Martyr had been murdered in 978. The supposed place of his murder is traditionally on, or near, the castle mound. Corfe was one of the first English castles to be built in stone - at a time when earth and timber were the norm. This may have been due to the plentiful supply of good building stone on Purbeck.

Sir John Bankes bought the castle in 1635, and was the owner during the English Civil War. His wife, Lady Mary Bankes, led the defence of the castle when it was twice besieged by Parliamentarian forces. The first siege, in 1643, was unsuccessful, but by 1645 Corfe was one of the last remaining royalist strongholds in Southern England and fell to a siege ending in an assault. In March that year Corfe Castle was '"slighted" (demolished) on Parliament's orders. Owned by the National Trust, the castle is open to the public. It is protected as a Grade I listed building and a Scheduled Ancient Monument.

The isle[edit]

A large part of the district is now designated as an Area of Outstanding Natural Beauty (AONB), but a portion of the coast around Worbarrow Bay and the ghost village of Tyneham is still, after nearly 60 years, in the possession of the Ministry of Defence who use it as a training area. Lulworth Ranges are part of the Armoured Fighting Vehicles Gunnery School at Lulworth Camp. Tanks and other armoured vehicles are used in this area and shells are fired. Due to safety reasons, right of entry is only given when the army ranges are not in operation. Large red flags are flown and flashing warning lamps on Bindon Hill and St Alban's Head are lit when the ranges are in use.[8] At such times the entrance gates are locked and wardens patrol the area.

Other places of note are:

  • Swanage, at the eastern end of the peninsula, is a seaside resort. At one time it was linked by a branch railway line from Wareham; this was closed in 1972, but has now partially reopened as the Swanage Railway, a heritage railway.
  • Studland: This is a seaside village in its own sandy bay. Nearby, lying off-shore from The Foreland (also Handfast Point), are the chalk stacks named Old Harry Rocks: Old Harry and his Wife.
  • Poole Harbour is popular with yachters; it contains Brownsea Island, the site of the first-ever Scout camp.
  • Corfe Castle is in the centre of the isle, overlooking Corfe Castle village.
  • Langton Matravers, which was once the home of several boys preparatory schools; the last of these, The Old Malthouse School, closed in 2007.
  • Kimmeridge Bay, with its fossil-rich Jurassic shale cliffs, and site of the oldest continually working oil well in the world.

See also[edit]

Notes[edit]

External links[edit]

Coordinates: 50°38′15″N2°03′28″W / 50.6376°N 2.0579°W / 50.6376; -2.0579

  1. ^An inquisition taken at Corfe Castle in 1370 quotes a document that affirms "that the whole Isle of Purbeck is a warren of our lord the King and pertains to his said castle, and it extends from a path which is between Flouresberi and the wood of Wytewey and thence as far as Luggerford, from that to the bridge of Wareham, and so along the sea, in an easterly direction, to a place called the Castle of Stodland; thence by the sea-coast to the chapel of St Aldhalm, and from thence still by the sea-coast towards the west until it again reaches the aforesaid place of Flouresberi". Mentioned in Hyland, Paul (1978). Purbeck: The Ingrained Island. Victor Gollancz Ltd. p. 18. ISBN 0-575-02440-2. 
  2. ^Wightman, Ralph (1983). Portrait of Dorset (4 ed.). Robert Hale. p. 178. ISBN 0-7090-0844-9. 
  3. ^"NCA Profile: 136 South Purbeck (NE370)". Natural England. 2015-02-05. Retrieved 2015-11-28. 
  4. ^See Simms, Wilfrid F., "Railways of Kimmeridge" (discussing slate railways)(1999)(ISBN 095288819X).
  5. ^ abPratt, Edward A. (2008). The Wild Flowers of The Isle of Purbeck, Brownsea and Sandbanks. Brambleby Books. 
  6. ^Excavations on the Roman Villa at Bucknowle Farm, Corfe Castle, Summary of Work 1976-84, Dorset County Museum
  7. ^Richmond, I. A. (1955). Roman Britain. The Pelican History of England. Harmondsworth, Middlese: Penguin Books. p. 160. 
  8. ^"Public access to military areas: Lulworth ranges". Ministry of Defence. 2014-11-19. Retrieved 2015-11-28. 

One thought on “Isle Of Purbeck Dorset Case Study

Leave a comment

L'indirizzo email non verrà pubblicato. I campi obbligatori sono contrassegnati *