Limestone pavement, inland cliffs and screes

Context

This reporting category covers both natural and artificial exposed rock surfaces, such as inland cliffs, caves, and screes and limestone pavements, as well as various forms of excavations and waste tips such as quarries and quarry waste.  These habitats are typically upland in distribution, though there are examples in the lowlands, especially of calaminarian grassland. 
 
A number of vegetation types associated with rock habitats are also included in this reporting category.  These are:
  • chasmophytic vegetation (plant communities that colonise the cracks and fissures of rock faces);
  • calaminarian grassland (a grassland type which is found on soils which have levels of heavy metals, such as lead, chromium and copper, that are toxic to most plant species); and
  • certain types of tall herb and fern vegetation, which as a result of grazing pressure are much reduced in extent and confined to areas inaccessible to grazing animals such as cliff faces and ledges, and to a lesser extent, on lightly-grazed steep rocky slopes and boulder fields.
 
SSSIs can be notified if they qualify under criteria outlined in Chapter 5 Non-montane rock habitats and Chapter 10 Artificial habitats (for calaminarian grassland) of the Guidelines for Selection of Biological SSSIs.  In Northern Ireland, ASSIs are selected on a very similar basis – the Guidelines for the Selection of Biological ASSIs in Northern Ireland is an addendum to the SSSI guidelines rather than an alternative. 
 

Summary statistics

  SAC A/SSSI Total
Favourable condition 60% 56% 58%
Main monitoring coverage E, S, W E, S  
Reported assessments 117 155 272
Completeness of assessments 67% unknown  
Distribution of features     UK
 

Number of assessments reported by country and site type

Country SAC SSSI/ASSI
England 34 115
Scotland 69 35
Wales 10 0
Northern Ireland 4 5
United Kingdom 117 155
 

Natura features

List of Natura 2000 interest features within this reporting category

Interest feature name  
Formal name Informal name No. of assessments reported Total no. of features % assessed
Calaminarian grasslands of the Violetalia calaminariae Grasslands on soils rich in heavy metals 18 20 90%
Calcareous and calcshist screes of the montane to alpine levels (Thlaspietea rotundifolii) Base-rich scree 10 11 91%
Calcareous rocky slopes with chasmophytic vegetation Plants in crevices in base-rich rocks 25 35 71%
Caves not open to the public Caves not open to the public 4 6 67%
Hydrophilous tall herb fringe communities of plains and of the montane to alpine levels Tall herb communities 15 28 54%
Limestone pavements Limestone pavements 8 12 67%
Siliceous rocky slopes with chasmophytic vegetation Plants in crevices on acid rocks 18 33 55%
Siliceous scree of the montane to snow levels (Androsacetalia alpinae and Galeopsietalia ladani) Acidic scree 19 29 66%
 
Natura 2000 comprises Special Protection Areas (under the Birds Directive) and Special Areas for Conservation (under the Habitats and Species Directive). The list presented here includes all of the qualifying interest features under these Directives, and shows the proportion of these features for which a condition assessment has been made.
 

SSSI features

List of SSSI and ASSI interest features in this reporting category

Interest feature name  
Formal name Informal name No. of assessments reported
Calaminarian grassland and serpentine heath Calaminarian grassland and serpentine heath 6
Inland Rock Calcerous rocky slopes with chasmophytic vegetation 1
Inland Rock Cliff & scree 1
Inland Rock Inland rock 115
Inland Rock Siliceous rocky slopes with chasmophytic vegetation 1
Inland Rock Siliceous scree of the montane to snow levels (Androsacetalia alpinae and Caleopsietalia ladani) 1
Inland Rock Calcerous and calcshist screes of the montane to alpine levels 1
Limestone pavement Limestone pavement 3
Rocky slopes Rocky slopes 11
Siliceous scree Siliceous scree 1
Tall herb ledge Tall herb ledge 14
 
This list has not been fully standardised at a UK level yet. It is intended to show the principal constituent "feature types" for this reporting category.
 

Maps - distribution

UK distibution of reported interest features

Distribution of reported interest features.

Map showing the locations of the 10km squares in which at least one condition assessment has been reported. It does not show features that have not yet been assessed.

 

Maps - Natura

Distribution of SAC features showing assessments of favourability Condition of SAC features, with those currently reported as unfavourable-recovering shown as favourable
Current condition of SAC features
Distribution of SAC features showing assessments of favourability (where unfavourable-recovering is counted as unfavourable).
Condition of SAC features, with those currently reported as unfavourable-recovering shown as favourable
The implication of the unfavourable-recovering condition assessments is that at some point in the future these features should become favourable. This map shows the effect of that recovery by counting the favourable and unfavourable-recovering assessments together.

 

IMPORTANT NOTE: we do not have information on the timescale of the predicted recovery, which may be influenced by many past, natural and human related factors. A sustained sympathetic management regime is more likely to result in favourable condition being attained.

Key: Proportion of assessed features on 10km squares that are favourable:

Natura map legend - Key: proportion of assessed features on 10km squares that are favourable

 

Details of how these maps were produced

 

Maps - SSSI

Current condition of SSSI/ASSI features Condition of SSSI/ASSI features, with those currently reported as unfavourable-recovering shown as favourable
Current condition of SSSI/ASSI features
Distribution of SSSI/ASSI features showing assessments of favourability (where unfavourable-recovering is counted as unfavourable).
Condition of SSSI/ASSI features, with those currently reported as unfavourable-recovering shown as favourable
The implication of the unfavourable-recovering condition assessments is that at some point in the future these features should become favourable. This map shows the effect of that recovery by counting the favourable and unfavourable-recovering assessments together.

 

IMPORTANT NOTE: we do not have information on the timescale of the predicted recovery, which may be influenced by many past, natural and human related factors. A sustained sympathetic management regime is more likely to result in favourable condition being attained.

Key: Proportion of assessed features on 10km squares that are favourable:

SSSI map legend - Proportion of assessed features on 10km squares that are favourable

 

Details of how these maps were produced

 

Condition summary

Reporting category condition summary on Natura 2000 sites and SSSI

This lists the 10 different condition assessments and presents a bar chart showing the number of features within the SSSI series and the Natura 2000 series (either SPA for bird features or SAC for features other than birds). Note that for Natura 2000 we are able to estimate the number of features that have not been assessed during the 6 year reporting period - we are unable to do this for SSSI/ASSI because we do not have an overall list of notified interest features for these designations.

 

NB favourable unclassified and unfavourable unclassified have been used in this first six year cycle to get around difficulties in identifying trends in condition as common standards monitoring is implemented. It is expected that these categories will not be used for subsequent assessments of a feature.

 

Condition assessment - Natura 2000 features

The number and proportion of assessments for Natura 2000 (SAC and SPA) interest features falling into each of the condition categories
The number and proportion of assessments for Natura 2000 (SAC and SPA) interest features falling into each of the condition categories. Note that the �unfavourable� category includes all reports of unfavourable condition except �unfavourable recovering� which is shown as a separate segment.
 

Condition assessment - SSSI features

The number and proportion of assessments for SSSI/ASSI interest features falling into each of the condition categories
The number and proportion of assessments for SSSI/ASSI interest features falling into each of the condition categories. Note that the �unfavourable� category includes all reports of unfavourable condition except �unfavourable recovering� which is shown as a separate segment.
 

Adverse activities

The number of interest features where an activity has been reported as being implicated in the "unfavourable" condition of a feature
The number of interest features where an activity has been reported as being implicated in the "unfavourable" condition of a feature. More than one adverse activity may be reported for each feature.
 

Management measures

The measures summary bar chart lists the management measures relevant to the reporting category
For each "measure" the chart shows the number of interest features where that measure has been taken on a site to improve or maintain the condition of an interest feature. More than one measure may be reported for each feature assessed.
 

Interpretation

58% of rocky habitat features reported are in favourable condition.  This is well above the average for terrestrial habitats, above the average for habitat features, and about the average for all features combined.  56% of the SSSI/ASSI features and 60% of SAC features reported are in favourable condition.  14% of A/SSSI and 20% of SAC features reported are unfavourable-recovering. 
 
There is considerable variation between habitats types in the reporting category.  The percentage of features reported in favourable condition includes 25% of caves, 27% of limestone pavements, 71% of crevice habitats, 72% of scree habitats (both acid and base-rich), and 79% of herb-rich habitats.  
 
The reported activity that has had the greatest impact contributing to unfavourable condition on rocky habitat features is over-grazing.  This leads to loss of vegetation structure and the failure of more palatable or vulnerable species to reproduce and maintain themselves.  It can also lead to the loss of plant species and associated fauna, and the spread of rank, unpalatable plant species.  In extreme cases, very heavy grazing and trampling can lead to exposure of bare soil and erosion.  There is, therefore, a need for grazing to be undertaken at the right time and with the right intensity.  The reporting of measures taken to address unfavourable condition indicates that management agreements/schemes and agri-environment schemes are in place on many sites.  However, it is not yet known how long it may take to return rocky habitat features to favourable condition.

Calaminarian grassland

46% of calaminarian grassland features reported are in favourable condition.  67% of A/SSSI and 39% of SAC features reported are favourable.  A further 28% of SAC features reported are unfavourable-recovering. 
 
Unfavourable condition has resulted at least partly from under-management and successional change.  Supplementary feeding can also cause problems through intensive trampling and dunging in limited areas.  Underlying causes of under-management are still thought to be largely due to current agricultural economics and policies, leading to a reluctance to keep stock on pasture perceived to have little nutritional value.  The extent to which atmospheric nutrient deposition is affecting the composition of grassland sites is a largely unknown quantity.