148 The Essex Naturalist
Common SSSIs) are starting to receive the management attention they need to
restore the lowland heath habitats.
Grassland
One of the most telling statistics about Essex is that at least 99% of its species-
rich grassland has been lost or damaged this century, the result of agricultural
intensification coupled with urban and industrial development. Much of the
remaining grassland of interest is now in very small parcels, such as road verges
or graveyards, too small to merit consideration for SSSI notification. Even those
sites which are notified for their grassland habitats may contain only a small
proportion of open grassland; for example, the calcateous grassland of Grays-
Thurrock Chalk Pit is confined to a narrow strip around the cliff edge, and there
are areas of acid grassland scattered around the Roman River and Epping Forest
SSSIs. In truth, these are best considered to be mosaic sites, leaving only a
handful of genuine grassland SSSIs such as Basildon Meadows, managed as part
of the One Tree Hill country park. It is a sad reflection of the state of the
county's grassland that such key indicators as yellow rattle are now effectively
absent from all but the few grassland SSSIs.
Mosaic sites
Rather few of our biological SSSIs consist of just one habitat type, and several
are made up of such a mixture of habitats that they cannot easily be assigned to
a single category. The group of SSSIs on the Danbury Ridge are one such
example, comprising woodland (both ancient and secondary), grassland (acid
and neutral), wet and dry heath, and marshland. It is the mosaic which supports
such a diverse range of species, characteristic of each component and the
transitions between them. To take another example, the Roman River SSSI
with a similar mix of habitats has a Lepidoptera fauna comprising almost a half
of all the British species. In one respect, managing such sites is difficult as it is
impractical to maintain specifically every element; on the other hand, simply
maintenance of the mosaic should be sufficient to cater for most of the
biodiversity therein.
Single-interest SSSIs
The published guidelines under which SSSIs are selected quite rightly focus
upon habitats. However, they also allow for notification of certain sites for
particular, usually species, interests. Sandbeach Meadows, two isolated grass
fields amidst the arable desert of the Dengie Peninsula, are a case in point: they
are of importance only as a secure feeding location for brent geese, in nationally
important numbers. In the far south of the county, Hangman's Wood is another
example. This fragment of ancient woodland is not of sufficient quality or extent
to justify SSSI status in its own right; its interest lies in the deneholes, ancient
chalk mines, which are now an important hibernaeulum for four species of bats.