Calcareous grasslands - lowland

Context

Lowland calcareous grassland is characterised by vegetation dominated by grasses and herbs on shallow, well-drained soils which are rich in bases (principally calcium carbonate) formed by the weathering of chalk and other types of limestone or base-rich rock.  Although the base status of such soils is usually high, with a pH of above 6, it may also be more moderate and calcareous grassland communities can occur on soils with a pH as low as 5.  Lowland is defined as below the level of agricultural enclosure.  The altitude at which this occurs varies across the UK, typically becoming higher as one travels South. 
 
Lowland calcareous grasslands support a very rich flora including many nationally rare and scarce species such as monkey orchid Orchis simia, hoary rockrose Helianthemum canum and pasque flower Pulsatilla vulgaris.  The invertebrate fauna is also diverse and includes scarce species like the adonis blue Lysandra bellargus, the silver-spotted skipper Hesperia comma, the Duke of Burgundy fritillary Hamaeris lucina and the wart-biter cricket Decticus verrucivorus.
 
SSSIs can be notified if they qualify under criteria outlined in Chapter 3 Lowland grasslands 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 27% 29% 29%
Main monitoring coverage E, W E, S  
Reported assessments 48 577 625
Completeness of assessments 94% unknown  
Distribution of features     GB
 

Number of assessments reported by country and site type

Country SAC SSSI/ASSI
England 44 549
Scotland 0 28
Wales 4 0
Northern Ireland 0 0
United Kingdom 48 577
 

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
Semi-natural dry grasslands and scrubland facies: on calcareous substrates (Festuco-Brometalia) Dry grasslands and scrublands on chalk or limestone 32 34 94%
Semi-natural dry grasslands and scrubland facies: on calcareous substrates (Festuco-Brometalia) (important orchid sites) Dry grasslands and scrublands on chalk or limestone, including important orchid sites 16 17 94%
 
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
Calcareous grassland - lowland Calcareous grassland - lowland 577
 
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

29% of lowland calcareous grassland features reported are in favourable condition.  This is below the average for terrestrial habitats and well below the average for all habitats or all features combined.  29% of SSSI, and 27% of SAC features reported are in favourable condition. 
 
Although the poor condition of these features is obviously worrying, many sites have management in place to promote a return to favourable condition.  Thus the unfavourable-recovering category accounts for a significant proportion of assessments reported (40% of A/SSSIs and 54% of SACs). 
 
Under-grazing and abandonment are the main causes of unfavourable condition, commonly resulting in scrub encroachment, sometimes together with invasive species problems.  Additionally, some sites are affected by overgrazing and nutrient enrichment.  Underlying causes of under-management are still thought to be largely due to current agricultural economics and policies.  Nutrient-enrichment through fertilizer application is still a concern, but is very difficult to monitor.  In addition, the extent to which atmospheric nutrient deposition is affecting the composition of grassland sites is a largely unknown quantity.