Lowland Calcareous Grassland - Habitat Action Plan

Ref 2/H8 Habitat Action Plan 8
Plan Author: Norfolk Wildlife Trust
Plan Co-ordinator: Farmland BAP Topic Group
Plan Leader: Natural England
Final May 2007

Action Plan Summary

Current Status

National Status

  • Lowland calcareous grasslands are developed on shallow lime-rich soils generally overlying limestone rocks, including chalk. These grasslands are now largely found on distinct topographic features such as escarpments or dry valley slopes and sometimes on ancient earthworks in landscapes strongly influenced by the underlying limestone geology. More rarely, remnant examples occur on flatter topography such as in Breckland and on Salisbury Plain. They are typically managed as components of pastoral or mixed farming systems, supporting sheep, cattle or sometimes horses; a few examples are cut for hay.
  • The cover of lowland calcareous grassland has suffered a sharp decline in extent over the last 50 years. There are no comprehensive figures, but a sample of chalk sites in England surveyed in 1966 and 1980 showed a 20% loss in that period.
  • Current estimates put the amount of lowland calcareous grassland remaining in the United Kingdom at 40,594 ha.
  • Lowland calcareous grasslands support a very rich flora including many nationally rare and scarce species such as pasque flower (Pulsatilla vulgaris). The invertebrate fauna of calcareous grassland is also diverse and includes the wart-biter cricket (Decticus verrucivorus). These grasslands also provide feeding or breeding habitat for a number of scarce or declining birds including stone curlew (Burhinus oedicnemus) and skylark (Alauda arvensis).
  • Scrub is frequently associated with calcareous grassland and can contribute to local biodiversity by providing shelter for invertebrates and scrub edge conditions suitable for species such as bloody cranesbill (Geranium sanguineum). Dwarf shrubs and herbs characteristic of acid soils are also sometimes associated with calcareous grassland, forming chalk or limestone heath.

Norfolk Status

  • Although chalk underlies about 60% of Norfolk, there is very little typical chalk grassland due to the glacial drift deposits which cover the county. The main sites which survive are in north-west Norfolk and Breckland, where natural features such as steep slopes or patterned ground support chalk grassland. Man-made features also support chalk grassland and these range from ancient sites to the more modern, such as the disused railway line at Narborough and Alderford quarry.
  • The boulder clay grasslands of south-east Norfolk sometimes show a strong calcareous influence, but these are largely treated as lowland meadows unless there is a significant calcareous grassland interest. Occasionally, more neutral meadows have chalk springs arising, leading to localised chalk flora; thus, it should be noted that this plan deals with those grasslands defined by the NVC types and typically resulting from thin soils over chalk.
  • The main chalk grassland communities found in Norfolk are: CG2 (Festuca ovina-Avenula pratensis); and CG7 (Festuca ovina-Hieracium pillosella-Thymus pulegiodes), which is characteristic in the Brecks and better developed here than elsewhere in the country. CG6 (Heliotrichon pubescens) is rare, but does occur on a few sites, including within the Stanford Training Area.
  • In Breckland, CG7b and CG7c occur in close association with acid grassland. Patches of calcareous grassland, within a mosaic of Brecks heath, are more common than large tracts, requiring different management from lowland calcareous grasslands in other areas. Most sites within Breckland occur within existing SSSIs or CWS, except for rides within Thetford Forest, which are largely not notified, plus isolated churchyards and road verges.

Links with Species Action Plans

  • Lowland calcareous grassland is an important habitat for a number of priority invertebrate, plant and bird species. During plan implementation, their requirements should be taken into account. The priority species relevant to Norfolk include: the pale shining brown moth (Polia bombycina) and the four spotted moth (Tyta luctuosa). BAP priority bird species closely associated with chalk grassland include stone curlew (Burhinus oedicnemus) and skylark (Alauda arvensis).

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Current factors causing loss or decline of the habitat in Norfolk

Both the quality and the extent of calcareous grassland can be affected by the following factors:

  • Agricultural intensification by use of fertilisers, herbicides and other pesticides, re-seeding or ploughing for arable crops. Particular problems include pig units and the wind blow of nutrients into chalk grassland banks.
  • Farm specialisation towards arable cropping has reduced the availability of livestock in many lowland areas; this is especially true of sheep. The result is the increasing dominance of coarse grasses such as false oat grass (Arrhenatherum elatius), cocksfoot (Dactylis glomerata) and bush grass (Calamagrostis epigejos), followed by the more damaging invasion by scrub and woodland, which leads to losses of calcareous grassland flora and fauna.
  • The decline in the availability of grazing stock, especially sheep, is a significant factor in both the decline of existing habitats and the opportunities for managing sites in the future. Over-grazing is less of a problem in Norfolk than in other counties, but is sometimes associated with supplementary feeding, which can also cause localised sward damage, as a result of trampling and long-term nutrient enrichment.
  • Development activities such as mineral and rock extraction, road building, housing and landfill.
  • Localised afforestation with hardwoods and softwoods; this has been especially evident in the Brecks.
  • Recreational pressure bringing about floristic changes associated with soil compaction at some key sites.
  • Invasion by non-native plants, including bird-sown Cotoneaster species, causes problems by smothering calcareous grassland communities at some sites.
  • Atmospheric pollution and climate change, the influence of which are not fully assessed.
  • The loss of calcareous grassland in Breckland is linked to the dramatic loss (22,000 ha in the 20th century) of heathland and dry grassland. Many of the surviving areas have declined in quality as sheep grazing has ceased and rabbit populations declined due to myxamytosis.
  • Many remaining calcareous grassland sites are small in size and isolated from other sites, exacerbating the problems of management and vulnerability to external threats, such as agricultural spray drift.
  • It is possible that in the past chalk grassland sites have not been seen as a priority for conservation in Norfolk, as the county is not, on the whole, as well known for this habitat as other areas are. Furthermore, many calcareous grasslands occur as part of man-made sites and as such are sometimes overlooked.

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Current Action in Norfolk

Statutory Designations

  • Lowland calcareous grassland features prominently in the SSSI series in England and Wales and the value of the habitat has long been recognised in the NNR series. Statutory calcareous grassland sites of note in Norfolk include the following SSSIs:

    1. Stanford Training Area: 955.56 ha (mosaic including neutral dry grassland)
    2. Barnhamcross Common: 69.07 ha
    3. East Walton & Adcocks Common: 59.71ha
    4. Warham Camp: 19.12 ha
    5. Cockthorpe Common: 7.02 ha
    6. Ringstead Downs: 7.02 ha
    7. Weeting Heath (in part): 141.75 ha
    8. Alderford Common: 17.19 ha
    9. Narborough Railway embankment: 7.94 ha
     
  • Lowland calcareous grassland is included within the Festuco-brometalia grassland identified in Annex 1 of the EC Habitats Directive as of Community interest. The habitat is a priority type if important orchid populations are present. Lowland calcareous grassland sites form part of the Natura 2000 network.
  • Lowland calcareous grassland is part of the Special Area of Conservation feature for Breckland.
  • Several plant, invertebrate and bird species of calcareous grassland are protected under the Schedules of the Wildlife and Countryside Act 1981, including ground pine (Ajuga chamaepitys) and spiked speedwell (Veronica spicata).

Other Action

  • A Botanical Survey of East Anglian Calcareous Grassland (Moore, 1997) and the Norfolk Grassland Survey (Roberts and Smyth, 1990) provided studies of key grassland sites, including NVC and rare species information. However, much of the information they contain is now out of date and Natural England is embarking upon an update of grassland information across the eastern region. The lack of current and digitised information on the distribution of the habitat in Norfolk creates a requirement to collect and collate existing data on the extent of both the current and historical resource; this has to some degree been addressed through the Norfolk Grassland Audit (Harris, 2006), but information on current site condition is still lacking for non-statutory sites.
  • Of the 1,231 County Wildlife Sites notified in Norfolk, 750 contain grassland habitat; of these, 91 are predominantly NVC communities considered important for nature conservation. County Wildlife Sites across Norfolk are provided with free advice on management and grant aid by Norfolk Wildlife Trust and are afforded a degree of protection under the development and planning processes. Non-statutory calcareous grassland sites of note in Norfolk include the following County Wildlife Sites:

    1. Hollow Heath (CWS No. 725): 12.16 ha
    2. Merton Common (CWS No. 731): 11.1 ha
    3. String Drain (CWS No. 308): 8.05 ha
    4. Watton Airfield (CWS No. 2091): 5.07 ha
    5. Castle Acre Castle mound (CWS No. 2056): 3.2 ha
    6. Walsingham disused railway cuttings (CWS No. 1303): 3.08 ha
     
  • A number of chalk quarries in Norfolk are being or will be restored to calcareous grassland. Some river banks in the west of the county and the spoil from the Cut-off Channel also support chalk flora and might be considered for survey and CWS status in the future. Some rides in Thetford Forest also support calcareous flora; these have been identified by the Forestry Commission and managed accordingly.
  • The regional under-grazing project (formerly an RDS initiative) attempts to find solutions to some of the problems caused by the decline of grazing stock in East Anglia.
  • Grassland habitats are the principal focus of the Churchyard Conservation Scheme (run by the Norfolk Wildlife Trust) and the Roadside Nature Reserve programme (run by NWT and Norfolk County Council.). These sites can provide a good source of local provenance seed.
  • On behalf of the Norfolk Biodiversity Partnership, NWT has recently undertaken an ecological network mapping project for the county (Land, 2006). The report of the project highlights areas where grassland re-creation is desirable to re-connect and buffer fragmented habitats.
  • The National Lottery funded Tomorrow’s Heathland Heritage project includes a component of chalk grassland where it forms part of a Brecks heath mosaic.

Management, Research and Guidance

  • Management agreements to conserve calcareous grassland on SSSIs have been made between owners and occupiers and English Nature (now Natural England). Agri-environment schemes play a major role in providing incentives to encourage the appropriate management of sites, including SSSIs (where a management agreement is not already in place).
  • The Breckland ESA contained a significant component of lowland calcareous grassland and the Countryside Stewardship Scheme included calcareous grassland as an eligible habitat for potential re-creation and extensive management elsewhere in the county. The Environmental Stewardship schemes will further promote appropriate grassland management: ELS offers options for low input grassland management, and HLS provides a broad range of grassland maintenance, restoration and re-creation options targeted at SSSIs, BAP habitats and species. Chalk grassland is targeted for the North West Norfolk Joint Character Area (JCA 076) and Breckland (JCA 085).
  • The Ministry of Defence is by far the largest landowner (by area) nationally of calcareous grassland with several sites including large areas within the Stanford Training Area, most of which are now notified as SSSI or CWS. The MoD is developing integrated management plans for their properties to take account of nature conservation.
  • A major contribution has been made by various non-governmental organisations to the conservation of species-rich calcareous grasslands in parts of the UK through the establishment of nature reserves. In Norfolk, notable nature reserves include NWT Ringstead Downs and NWT Narborough Railway Line
  • There is a need across the East Anglian region to ensure that the sustainable, long term management of calcareous grasslands is encompassed in plans to develop grazing networks and projects. This encompasses the need to tackle the poor availability of suitable grazing stock for many grassland sites and the problems of grazing small, fragmented sites.
  • Nationally, there is a need to assess the impact of atmospheric nutrient deposition and climate change in this and other types of lowland grassland.

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Action Plan Objectives and Targets

National

  • Maintain the current extent of lowland calcareous grassland in the UK. (Target represents no loss of BAP habitat).
  • Maintain at least the current condition of lowland calcareous grassland.
  • Achieve favourable or recovering condition for 30,421 ha of lowland calcareous grassland by 2010.
  • Restore 399 ha of lowland calcareous grassland from semi-improved or neglected grassland, which no longer meets the priority habitat definition by 2010.
  • Re-establish 8,424 ha of grassland of wildlife value from arable or improved grassland by 2010.
  • 6,320 ha (75%) of re-established area to be adjacent to existing lowland calcareous grassland or other semi-natural habitat by 2010. (Refer to T5)
  • 4,200 ha (50%) of re-established area to contribute to resultant habitat patches of two ha or more of lowland calcareous grassland by 2010. (Refer to T5)

Norfolk

  • Establish, through audits, desk studies and field work, a more accurate figure for the extent of lowland calcareous grassland in Norfolk by 2008.
  • Maintain the existing resource, currently estimated as 182.38 ha (Harris, 2006) through advisory work, protection under the land use planning system and increased publicity about the importance of semi-natural grasslands.
  • Wherever biologically feasible, achieve favourable status of all significant stands of unimproved lowland calcareous grasslands within SSSIs by 2010.
  • For stands outside SSSIs, wherever biologically feasible, secure favourable condition over 75 per cent of the resource by 2015. This will focus mostly on CWS, with some attention being accorded to churchyards and Roadside Nature Reserves.
  • Restore 50 ha of lowland calcareous grassland from neglected or improved grassland by 2015.
  • Re-establish 30 ha of lowland calcareous grassland from arable or other land by 2015.
  • By 2010, 75 per cent (60 ha) of the restored/re-established area should be adjacent to existing lowland calcareous grassland or other semi-natural habitat, and 50 per cent (40 ha) should contribute to resultant habitat patches of 2 ha or more of lowland calcareous grassland.

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