Acid Grassland Habitat
Audit
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Summary
Acid
grassland generally consists of fine-leaved grasses such
as common bent and fescues, with typical herbs such as sheep's
sorrel, tormentil and heath bedstraw. Acid grassland
flora is sometimes associated with lowland heath and mire
communities. This assemblage is commonly found on
nutrient-poor, free-draining and acidic soils underlain
by the sands of bagshot beds, gravels, sandstones and acid
igneous rocks.
Although
acid grassland is one of the most extensive semi-natural
habitats in the United Kingdom, there are scant data on
its true extent. Estimates suggest that there is
in excess of 1,200,000 ha of acid grassland in the uplands
but in the lowlands there is unlikely to be more than 30,000ha.
Acid grassland is widespread throughout London; only six
out of the thirty-three London boroughs have no recorded
areas of acid grassland. There are several quite
extensive areas, particularly in the Royal Parks in west
London, the southern part of Epping Forest in north London
and Wimbledon Common.
Lowland acid grassland is becoming increasingly rare in
Britain. Although intrinsically less species-rich
than neutral or chalk grassland of similar quality, acid
grassland contains many characteristic species that do not
occur widely in other grassland types. Nationally rare plants
such as clustered clover Trifolium glomeratum, fine-leaved
sandwort Minuartia hybrida and autumn squill Scilla
autumnalis can all be found in acid grassland in London.
Even within central London, in the City of Westminster,
a tiny patch of acid grassland supports harebell Campanula
rotundifolia. More typical acid grassland species include
mat grass Nardus stricta, early hair-grass Aira
praecox and sheep’s sorrel Rumex acetosella.
Acid grasslands
are also valuable for invertebrates, especially hymenoptera
(ants, bees and wasps) such as the mining bee Andrena
florea; and butterflies such as green hairstreak and
small copper. Few bird species have a particular association
with acid grasslands, but green woodpecker, meadow
pipit and linnet are invariably present on the larger acid
grassland sites.
Although
much reduced in area and distribution and varying in quality,
acid grassland is still a significant habitat in Greater
London, particularly in the many parks and commons. It is,
however, a fragile habitat which requires careful management.
Many formal parks and open spaces contain areas of acid
grassland and relaxation of the mowing regime in these areas
will quite quickly result in some enhancement of biodiversity
· common blue, small heath and small copper butterflies
could be encouraged to breed, for example. A considerable
amount of acid grassland also occurs on some of London’s
older golf courses and a similar programme of identifying
key areas and modifying mowing regimes could result in considerable
benefit to biodiversity without seriously detracting from
the primary purpose of the course.
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the full Audit - the above is only a summary.
Acid Grassland
Habitat Action Plan - coming soon
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