Calcareous grasslands - upland

Context

Upland 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 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. 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.

Calcareous, or limestone, grasslands contain an exceptional diversity of rare plants, but are particularly characterised by a series of widespread grassland plants which are mainly restricted to lime-rich soils. Species include grasses such as common bent Agrostis capillaris, sweet vernal grass Anthoxanthum odoratum, quaking-grass Briza media, heath-grass Danthonia decumbens, sheep's-fescue Festuca ovina, and blue moor-grass Sesleria caerulea; sedges such as hair sedge Carex capillaris, spring sedge C. caryophyllea, glaucous sedge C. flacca, and carnation sedge C. panicea; and forbs such as harebell Campanula rotundifolia, limestone bedstraw Galium sterneri, common rock-rose Helianthemum nummularium, fairy flax Linum catharticum, mossy saxifrage Saxifraga hypnoides, wild thyme Thymus polytrichus and common dog-violet Viola riviniana. Calcareous grasslands in the montane zone are included under the Montane grasslands and heaths 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

	SAC	A/SSSI	Total
Favourable condition	15%	25%	23%
Main monitoring coverage	E, S	E, S
Reported assessments	20	64	84
Completeness of assessments	59%	unknown
Distribution of features			UK

Number of assessments reported by country and site type

Country	SAC	SSSI/ASSI
England	7	48
Scotland	12	14
Wales	0	0
Northern Ireland	1	2
United Kingdom	20	64

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	8	12	67%
Species-rich Nardus grassland, on siliceous substrates in mountain areas (and submountain areas in continental Europe)	Species-rich grassland with mat-grass in upland areas	12	22	55%

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 - subalpine	Calcareous grassland - subalpine	14
Calcareous grassland - upland	Calcareous grassland - upland	50

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

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
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.

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

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. 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. 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. More than one adverse activity may be reported for each feature.

Management measures

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 upland calcareous grassland features reported are in favourable condition. This result is well below the average for terrestrial habitats, all habitats, and all features combined. 25% of the A/SSSI and 15% of SAC features reported are in favourable condition. A further 34% of A/SSSI and 20% of SAC features reported are unfavourable-recovering. These results raise serious concerns that, at more than three out of four sites, calcareous grassland features are failing to achieve favourable condition.

The reported activity that has had the greatest impact contributing to unfavourable condition on upland calcareous grassland 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 upland calcareous grassland features to favourable condition.