Grasslands, Meadows and Pasture Habitat Audit - page 2
Nature Conservation Importance, Threats and Opportunities, Data Sources, Rationale and limitations
, Page 1
Nature Conservation Importance
It has been suggested that the loss of neutral grasslands in the lowlands represents the greatest reduction of wildlife habitat over the last 45 years (NCC, 1984). Between 1930 and 1984 semi-natural lowland grassland decreased by an estimated 97 in England and Wales (Fuller 1987), leaving just 3 undamaged by intensification (NCC, 1984). The extent and quality of the neutral grassland in London has shown a similar decline. Although neutral grasslands are still relatively common in London, unimproved (species-rich) neutral grasslands are particularly rare.
London’s neutral grasslands can be rich in wildflowers and there may be more than a dozen species of grass. Commonly occurring grass species on London’s neutral grassland include cocksfoot, Yorkshire fog, and sweet vernal grass. Nationally rare or declining wildflower species can be found amongst these grasses, including (in a handful of sites); meadow rue Thalictrum flavum, yellow vetchling Lathyrus aphaca, and chamomile Chamaemelum nobile. Other more typical neutral grassland species in London include pignut Conopodium majus, pepper saxifrage Silaum silaus, meadow vetchling Lathyrus pratensis, sneezewort Achillea ptarmica, black knapweed Centaurea nigra and cuckoo-flower Cardamine pratensis.
Several species of bird are also associated with neutral grassland habitat. The most evocative is perhaps the skylark, although this species, as well as short eared owl and meadow pipit which are also typical grassland species, require relatively large areas of grassland habitat and are not often encountered in the smaller patches of semi-natural grassland in London. Swallows, which regularly hawk for invertebrate prey over meadows and pastures, also require relatively large areas of habitat and are therefore largely confined to the outer London boroughs. The kestrel is less demanding and may hunt across widely scattered patches of grassland including road verges and uncut corners of playing fields and other amenity grasslands.
Neutral grasslands are also valuable for invertebrates. Several species of butterfly are dependent largely on semi-natural neutral grassland; meadow brown and common blue are relatively widespread, but small heath, small copper and Essex skipper are often confined to the better quality grassland sites. Many moth species occur in neutral grassland; the six-spot burnet moth is well distributed across London, whereas the chimney sweeper is restricted to a few sites which have never been subject to agricultural improvement. Perhaps one of the most characteristic grassland invertebrates is Roesel’s bush cricket, which occurs widely in grasslands throughout London. Conversely, species such as the tube-web spider Atypus afinis is only known to occur in a single location on Hampstead Heath.
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Some grassland, meadow and pasture sites of nature conservation value in Greater LondonArrandene Open Space and Featherstone Hill, LB Barnet |
Threats and Opportunities
Threats
Lowland neutral grassland has declined in quality and extent. The main threats currently affecting the habitat include:
 | Agricultural improvement such as fertiliser application, ploughing, drainage and reseeding. |
| Mowing and draining rough grasslands on golf-courses, country parks and playing fields to expand opportunities for formal recreation. |
| Lack of appropriate management neglect e.g. too frequent cutting, or over-grazing, resulting in a reduction of herb species in the sward; or lack of mowing or grazing resulting in reversion to rank grassland and scrub. |
| Fragmentation and isolation of the remaining habitat, particularly where areas of relatively species-rich neutral grassland become isolated on road-verges, golf course roughs or within an intensively farmed landscape. |
| Inappropriate tree-planting, particularly on rough grasslands which support important populations of invertebrates or grassland birds but may not be botanically diverse. |
| Direct loss of habitat due to development, particularly where the value of the grassland has been masked by frequent cutting or over-grazing. |
An important matter, particularly in London, is of the value of neutral grasslands being ‘masked’ by current management. It is likely that many potentially valuable areas of neutral grassland fall within frequently mown public parks and amenity open spaces, or in the many horse-grazed fields in London’s Green Belt. Relaxation of mowing or grazing can reveal areas of quite species-rich grassland.
Opportunities
This habitat is a high priority for action due to the severe decline in
quantity and quality of this habitat nationally and the relatively large neutral
grassland resource found within London.
Several areas of relatively species-rich neutral grassland could be restored by relaxation of mowing regimes in some of London’s older public parks and open spaces. Relaxation or modification of mowing regimes should be implemented after thorough survey to ensure that the areas that revert to a more natural sward are the most species-rich areas. Uncut areas of perennial ryegrass (the typical constituent of amenity swards) are of little value to people or wildlife. Rough grassland has already been restored in parts of some London parks with very beneficial results.
The restoration of a sympathetic grazing regime would be particularly beneficial to many neutral grassland sites. Although the botanical interest of several good quality grasslands in London is maintained by mowing or hay-making this is not usually the most beneficial management technique for biodiversity generally. Grazing is a more subtle form of management and creates a much wider range of micro-habitats which can be exploited by invertebrates and plant species which need gaps in the sward.
Making better use of grass as a crop (preferably hay) could encourage more sympathetic management. Presently the disposal of arisings is one of the main problems of managers of grassland sites where grazing is not an option. Encouraging machinery rings, where local authorities and private landowners share use of equipment such as cutters and balers, might help stimulate the restoration of some grassland sites to hay meadows. The meadows at Fryent Country Park in Brent are cut for hay and are certified under the Soil Association’s organic standard.
Data Sources
Fuller R.M. (1987). The changing extent and conservation interest of
lowland grasslands in England and Wales: A review of grassland surveys
1930-84. Biological Conservation 40, 281-300.
Hare T. (1988). London’s Meadows and Pastures. Ecology Handbook 8. London
Ecology Unit.
HMSO (1995). Biodiversity: The UK Steering Group Report. Volume 2 Action
Plans. London HMSO.
London Wildlife Habitat Survey (1984/5). Held by LEU, includes habitat dot
distribution maps, aggregated area figures and standardised information on
every survey parcel.
NCC (1984). Nature Conservation in Great Britain. Shrewsbury. Nature
Conservancy Council.
Wicks, D & Cloughley, P (Eds) (1998). The Biodiversity of Southeast
England: An Audit and Assessment. Hampshire and Isle of Wight Wildlife
Trust.
Rationale and limitations of approach
This audit covers areas of unimproved and semi-improved neutral grassland. The main area for potential overlap was with ‘wet’ grassland and marshes. These have been addressed within separate audits (‘Floodplain Grassland and Grazing Marsh’ and ‘Marshland’; audits HA7 and HA8 respectively).
Where ‘wet’ grassland was present, the following procedure was employed to attempt to gain a good estimate of neutral grassland. Data was taken from the London Wildlife Habitat Survey (1984/5). For each wet site, habitat parcel sheets were used to find out the area of parcel and the percentage of neutral grassland within the parcel. It was then possible to remove wet neutral grassland from borough and produce total neutral grassland figures for London.
However the following limitations should be noted:
| The figure taken as wet grassland will be artificially enhanced due to an amalgamation with dry neutral grassland within the same habitat parcel. |
| Sites with the wet overlay do not represent the full resource, as the wet overlay category was not a specified parameter within the 1984 Habitat Survey. Wet areas may have gone unrecorded. |
| Wet grassland may also have been omitted due to the seasonal nature of the habitat. |
| In addition, it is likely that neutral grassland is under-recorded owing to difficulties in locating all examples of this habitat. |
This approach removed some of the wet grassland resource for inclusion in the Grazing Marsh and Floodplain Grassland Audit.