E34 - Area of semi-natural grassland
Description
Related Indicators
Notes
Source: DETR, Countryside
Survey 1990, Digest of Environmental Statistics, No. 20, 1998, UK. Biodiversity
Steering Group Report 1995; UK. Biodiversity Group Tranche 2 Action Plans, Vol. 2,
1998; Bunce et al., Measuring Change in British Vegetation, ITE/DETR, 1999
Coverage: Great Britain
Semi-natural grasslands in Britain provide both an important resource for agriculture and an important habitat for wildlife. The value of such grasslands for wildlife largely depends upon the way in which they are managed. On the one hand, too intensive management through fertiliser and herbicide applications, overgrazing, early cutting or drainage improvements will lead to a decline in habitat quality and eventual habitat loss. But on the other hand, lack of management can lead to scrub or bracken invasion and loss of specialist grassland species.
It is estimated that as much as 97% of semi-natural lowland meadows has been lost since the 1930s in Englandand Wales. Between 1984 and 1990, the area of moorland grass in Great Britain fell by about 4%. The area of other semi-natural grasslands was, however, largely unchanged according to the Countryside Survey in 1990. Losses of moorland grass were mostly attributed to afforestation. Between 1978 and 1990, the species diversity of unimproved grassland decreased by 13% in Great Britain as a whole. The decline in species diversity in moorland grass was not statistically significant.
UK Biodiversity Action Plan has set targets for the maintenance and restoration of priority grassland habitats. Specific targets include:
The responsibility for achieving these aims is shared among a number of partner organisations, but MAFF’s agri-environment schemes will contribute to the restoration of these habitats in England.
Area
of agricultural land
Area of agricultural land under commitment to environmental
conservation
Populations of key farmland birds
Estimates for the extent and quality of semi-natural grassland in Great Britain are available from the Countryside Surveys of 1978, 1984 and 1990. A further survey was undertaken in 1998 but the results are not yet available.
The indicators are based on two replicated sets of data from the 1990 Countryside Survey: land-cover field survey (1984–90) and vegetation plots (1978–90). Data were obtained from a random stratified sample of one-kilometre squares throughout Great Britain.
The change in average species diversity per plot was calculated from 200 m2 vegetation plots sampled in both 1978 and 1990 which were classified as infertile grassland or moorland grass mosaic in 1978.
The change in area of moorland grass and other semi-natural grassland was estimated from the changes recorded in the replicated sample of one-kilometre squares in 1984 and 1990. Moorland grass refers to the land-cover categories of moorland grass and purple moor grass dominated moorland. Other semi-natural grassland refers to non-agriculturally improved grass, calcareous grass, upland grass, dune and maritime vegetation.
The data used in this indicator will be updated with 1998 data from the same replicate squares and plots as part of the Countryside Survey 2000. It is intended that the Broad Habitats classification developed by the UK Biodiversity Group will be used for reporting the results and this should avoid the problem of using different classifications for measurement of habitat extent and habitat quality. This will also provide a framework for comparing the general trends in semi-natural grasslands with the specific targets set for priority habitats.