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The Essex Naturalist
to the coast, with which there is considerable ecological interchange. Chingford
Reservoirs (largely within Greater London) and Hanningfield Reservoir have
also been notified as SSSIs by virtue of their wintering waterfowl populations.
The smaller freshwater bodies which have been protected through SSSI
notification are largely abandoned gravel workings. Turnford and Cheshunt Pits,
in the Lea Valley, are again notified for their waterfowl, whilst Glemsford Pits,
shared with Suffolk in the Stout Valley, has been designated for its outstanding
assemblage of Odonata. The same criterion was also used to justify SSSI status
for the Cornmill Stream & Old River Lea SSSI. In addition to the two Odonata
sites, there ate only two further SSSIs which include flowing water as a major
reason for their notification: Roman River and Holland Haven Marshes. The
latter can be considered a coastal site, as it represents a wholly-reclaimed
estuary, but the freshwater influence is central to maintaining the salinity
gradient on which the special interest depends. Indeed, freshwater inputs to all
saline systems are increasingly being recognised as key features, to provide
conditions suitable for brackish-water invertebrates, as well as drinking and
bathing areas for birds.
Often, it is the marshland habitats surrounding water bodies which are the
key features of a wetland SSSI. Several sites in the Stort Valley (Little
Hallingbury Marsh, Thorley Flood Pound, Hunsdon Mead) and Roding Valley
Meadows SSSI come into this category; furthermore, many large sites such as
Epping and Hatfield Forests have an important wetland component. In these
times of low rainfall and excessive abstraction, all wetland SSSIs must be
considered at risk.
Woodland
Essex is justifiably renowned for its woodlands. It has a larger area of ancient
woodland than in the test: of East Anglia put together, and taking a historical
view, it is apparent that we have lost a lower proportion this century than in
most other lowland counties. About thirty of the Essex SSSIs have a significant
woodland component, and it is largely these sites which are responsible for the
spread of SSSIs across the county. A glance at any map will show that
woodlands are clustered into particular areas, and the only two major complexes
which are not represented in the SSSI series are the Writtle Forest and
Markshall Woods. We anticipate that at least the latter omission may be
rectified, especially in view of its important small-leaved lime woods.
Lime is just one of the characteristic woodland types of Essex, as for example
also in Chalkney Wood. Other types include hornbeam (on both gravels and
London Clay), beech (around Epping Forest), ash-maple (on chalky boulder
clay), and more locally alder and wild cherry on the wetter sites. Most of the
woodland SSSIs are, or have been, actively managed by coppicing; in such cases,
we seek to ensure a continuation of the traditional practice which favours a wide
range of woodland flora and fauna. Every site has its special features, from oxlips