Lowland Calcareous Grassland

Habitat Description

Lowland calcareous grassland develops on shallow, lime-rich soils, usually overlying limestone rocks. The most significant areas of calcareous grassland in Northamptonshire are found on man-made sites where removal of upper strata has exposed underlying limestone and natural re-colonisation has occurred. In Northamptonshire it includes the following NVC communities:

   

CG2 Festuca ovina Avenula pratensis (sheep's fescue - meadow oat grass) grassland.

CG3 Bromus erectus (erect brome) grassland.

CG4 Brachypodium pinnatum (tor grass) grassland.

CG5 Bromus erectus Brachypodium pinnatum (erect brome tor grass) grassland.

CG3 is the dominant type within Northamptonshire, and is often the result of undergrazing. CG2 is a short sward community associated with heavy grazing of lowland calcareous grassland. CG4 and CG5 are rank, tussocky grassland, which like CG3 are associated with low levels of grazing.

Current UK Status and Trends

Sharp decline in extent by up to 50% over past 50 years, only 40,594 ha remain in the UK. Remnant patches are small and isolated.

Estimated Current Northants Resource

Approximately 300 ha.

Progress Towards BAP Targets 2002-2007

The Wildlife Trust's Grazing Project has helped find graziers for sites in need of grazing, and ensured that existing calcareous grasslands are grazed in a more positive manner. Provision for the creation of calcareous grassland was ensured through a planning agreement in Corby.

Main Issues and Threats

  • Quite a rare habitat in Northamptonshire with many important associated species. Much is isolated in small fragments, dangerously reducing species' population sizes and making it impossible for individuals to move between them.
  • Additional loss of habitat to development.
  • Inappropriate or lack of management (e.g. improving soils with nutrients, undergrazing) leading to domination by coarse grasses and invasion by scrub.
  • Recreational pressures causing soil compaction and floral changes.

General Strategies

  • Burrow down into the Green Infrastructure strategy on a field-by-field basis to identify the current resources and highest priorities for linkage by sympathetic management of degraded sites and establishment of new sites.
  • Expansion of the habitat by conversion of arable land and improved pasture in areas with suitable soil type and underlying geology to calcareous grassland.
  • Sympathetic management and restoration of existing sites, funded primarily through the Countryside Stewardship Scheme (Advice can be provided by The Wildlife Trust, RNRP or FWAG). Grazing management is vital to control coarse grasses and scrub.
  • Specific target areas are limestone slopes, mineral extraction and landfill sites.
  • In order to benefit invertebrates, management of calcareous grassland sites should not be uniform, but produce a mosaic of vegetation structure and composition: a knowledge of the species present on a site will allow management to be tailored appropriately.

Lead Partner

The Wildlife Trust

Associated National Priority Species

  • Basil thyme
  • Chalk carpet
  • Deep-brown dart (moth)
  • Dingy skipper
  • Dusky brocade
  • Ear moth
  • Four-spotted moth
  • Frog orchid
  • Galium carpet
  • Grass rivulet (moth)
  • Grizzled skipper
  • Hedge rustic (moth)
  • Large nutmeg (moth)
  • Latticed heath
  • Man orchid
  • Mellet's downy-back (beetle)
  • Purple milk-vetch
  • Rare spring-sedge
  • Red hemp-nettle
  • Rosy minor (moth)
  • Set-aside downy-back (beetle)
  • Shaded broad-bar (moth)
  • Small blue
  • Sky lark
  • The forester
  • Violet crowncup

Specific Management Required for Associated Species

Species

Northamptonshire Status

Management Prescriptions

Key Sites

Dingy skipper

Restricted

Common bird's foot trefoil is the main food plant. This is required in a sparse sward, with areas of open ground and taller vegetation for shelter and roosting, in a sunny sheltered position (Butterfly Conservation, 2008).

Twywell Hills and Dales Country Park.

Frog orchid

Very rare

Requires dry, well-grazed grassland.

Hardwick Meadow

Grizzled skipper

Restricted

Requires at least one of the main food plants (Rosaceae family) growing among short vegetation (< 10cm), with patches of bare ground, taller vegetation and scrub or woodland edges (Butterfly Conservation, 2008).

Twywell Hills and Dales Country Park.

Man orchid

Very rare

Grows particularly in abandoned chalkpits and limestone quarries, usually at the foot of slopes (David Lang, 2008).

Collyweston Quarries (1984 last record).

Purple milk-vetch

Very rare

Requires well-drained, well-grazed short turf, not improved with fertilizer or herbicides (JNCC, 2008).

Collyweston Quarries

Rare spring-sedge Very rare Grazing of grass layer on infertile soils over chalk or limestone. Harlestone Firs

Small blue

Very rare

Kidney vetch is the sole food plant. Requires dry sheltered grassland with sparse or eroding vegetation where kidney vetch seedlings can establish and where flowering plants are abundant. A mosaic of short and tall vegetation with some light scrub is usually best (Butterfly Conservation, 2008).

Brackley Railway Line Embankment

Violet crowncup

Rare

Associated with pine trees.

Twywell Hills and Dales Country Park

Targets

Target Code

Target Type

Target Description

Target Units

Northants Baseline Resource

Target

By

Unit Cost £

Total Cost £

NOR_LCG_T1

Maintain Extent

Maintain the current extent of at least LWS-standard Lowland Calcareous Grassland (no loss of BAP habitat).

Hectares

305

No Loss

2015

200/ha/yr

61,000/yr

NOR_LCG_T2

Achieving Condition

Achieve LWS condition on x ha of calcareous grassland by 2015.

Hectares

    

2015

200/ha/yr

  

NOR_LCG_T3

Restoration

Restore 60 ha of Lowland Calcareous Grassland to LWS-standard from semi-improved or neglected grassland by 2015.

Hectares

0

60

2015

2,063/ha

123,780 initial

NOR_LCG_T4

Expansion

Establish 30 ha of LWS-standard Lowland Calcareous Grassland from arable, improved grassland and mineral extraction and landfill sites by 2015.

Hectares

0

30

2015

2,100/ha + 280/ha/yr

63,000 initial

Actions

Action Code

Action Description

Lead Partner

Support Partner(s)

Related Target

NOR_LCG_HS_A1

Maintain approx 70 ha of calcareous grassland on Bradlaugh Fields, Collyweston, Twywell Hills and Dales and Old Sulehay.

The Wildlife Trust

  

NOR_LCG_T1

NOR_LCG_HS_A2

Restore favourable conditions on 0.5 ha of Irchester Country Park Quarry Bank.

NCC Countryside Service

  

NOR_LCG_T2

NOR_LCG_RE_A3

Prioritise areas for calcareous grassland creation and restoration, to maximise buffering and linkage of existing sites as well as overall patch size create maps like those for acid grassland by 2010.

The Wildlife Trust

NBRC

NOR_LCG_T3

NOR_LCG_HC_A4

Through section 106 agreements/new developments ensure that 10 ha of semi-improved or neglected grassland is restored to LWS calcareous grassland standard.

Developers, Local Authorities, WNDC, NNDC

  

NOR_LCG_T3

NOR_LCG_HC_A5

Restore 10 ha of semi-improved or neglected grassland to LWS standard acid grassland through the implementation of improved management.

Natural England

  

NOR_LCG_T3

NOR_LCG_HC_A6

Identify two mineral extraction or landfill sites on which 10 ha plus of calcareous grassland could be created and initiate the creation process by 2010.

Northamptonshire County Council

The Wildlife Trust

NOR_LCG_T4

NOR_LCG_HC_A7

Create 10 ha of calcareous grassland through section 106 agreements/new developments from arable, improved grassland and mineral extraction and landfill sites by 2015.

Developers, Local Authorities, WNDC, NNDC

  

NOR_LCG_T4

NOR_LCG_HC_A8

Create 10 ha of calcareous grassland through agri-environment or other grant schemes from arable land and improved grassland by 2015.

Natural England

RNRP, FWAG

NOR_LCG_T4