Acid grasslands - upland

Context

Upland acid grassland is characterised by vegetation dominated by grasses and herbs on a range of lime-deficient soils which have been derived from acid rocks such as sandstones, acid igneous rocks and on superficial deposits such as sands and gravels.  Although the habitat is typically species-poor, a wide range of communities occur in the UK.  Large expanses of acid grassland, uniform in character, occur in the uplands.  These areas have a limited biodiversity interest, but a proportion contribute to the conservation interest of the moor.  Upland is defined as above the level of agricultural enclosure.  The altitude at which this occurs varies across the UK, typically becoming lower as one travels North.  Acid grassland types and snow-bed communities which occur exclusively in the montane (alpine) zone are included in the Montane grasslands and heaths reporting category.
 
SSSIs can be notified if they qualify under criteria outlined in Chapter 9 Upland habitats 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

  A/SSSI Total
Favourable condition 23% 23%
Main monitoring coverage E  
Reported assessments 56 56
Completeness of assessments unknown  
Distribution of features   GB
 

Number of assessments reported by country and site type

Country SSSI/ASSI
England 54
Scotland 2
Wales 0
Northern Ireland 0
United Kingdom 56
 

SSSI features

List of SSSI and ASSI interest features in this reporting category

Interest feature name  
Formal name Informal name No. of assessments reported
Acid grassland - subalpine Acid grassland - subalpine 2
Acid grassland - upland Acid grassland - upland 54
 
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 - 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 SSSI/ASSI sites

This lists the 10 different condition assessments and presents a bar chart showing the number of features within the SSSI series. Note that we are unable to estimate the total number of SSSI/ASSI features 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 - 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

23% of the SSSI acid grassland features reported are in favourable condition.  This is well below the average for terrestrial habitats, all habitats, and all features combined.  29% of features reported are unfavourable-recovering.  These results raise serious concerns that features at more than three out of four sites are failing to meet favourable condition.
 
The reported activity that has had the greatest impact contributing to unfavourable condition on acid grassland features is over-grazing, though under-grazing also has an important impact. Both lead to the loss of vegetation structure and the failure of more palatable or vulnerable species to reproduce and maintain themselves. Both 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 upland acid grassland features to favourable condition.