SUGGESTIONS FOR FURTHER WORK
1. Conservation
It is tempting to focus attention on the rare or declining species when we consider
conservation priorities, but it is equally important to remember that species we now
consider common could quickly become scarce if their habitats are allowed to
deteriorate or be destroyed. Every reader of this book will know of a local pond, lake,
flooded pit, ditch or river which supports at least some common species. The vigilance
of local observers can obviously be crucial in identifying threats to such sites, in the
shape of planning applications, changes in adjacent land use, illegal tipping, over-
management or lack of management. Friendly contacts with local landowners or
responsible public authorities can often save sites that would otherwise disappear
simply because no-one was aware of their value. The excellent N.C.C. pamphlet, The
Conservation of Dragonflies (Chelmick et al. 1980) can be used as a supplement to
information contained in chapters 3 and 4 of this work for anyone needing to give
management advice on how to encourage dragonflies.
Sometimes dragonflies are attracted to garden ponds, and it is certainly worth
designing and managing a pond with dragonflies in mind. R. Dunn (1984) recommends
a sunny, but sheltered site, without overhanging trees. The pond should be as large as
possible, with shallow shelving margins. It should not be stocked with fish or water fowl.
Emergent vegetation such as Yellow flag and Soft Rush are recommended for the
margins, together with submerged oxygenators such as Spiked Water Milfoil.
The current dragonfly survey of Essex has established that several species which do
regularly breed in the county are very local and in need of special protection where they
occur. Seven species belong to this category:
(i) Brachytron pratense Currently known from only one site in the county, a rush-
filled ditch in a coastal marsh.
(ii) Cordulia aenea So far recorded from only four sites in the county - all four
being Epping Forest ponds. Populations here should be closely monitored,
and any management work undertaken with care.
(iii) Calopteryx virgo Probably has only one breeding site in the whole county.
Every care should be taken to retain the existing character of this site.
(i v) Platycnemis pennipes Occurs on only three river systems in Essex. The species is
in decline in one of these, has suffered from a major pollution incident in a
second, and is under threat from dredging in the third. Populations need to be
monitored very closely. The species is declining nationally, and is vulnerable
to pollution, dredging of the river bed. and clearance of marginal
vegetation.
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