Invertebrate survey at Gunpowder Park, the former Royal Ordnance Site in the Lee Valley
a tall monoculture of little value. The control of this plant is difficult but can be achieved with the
use of suitable herbicides. Its control in the open parts of Osier Marsh is likely to be necessary.
Older tree trunks are a valuable feature where the trunks are in the open. A number of rare
invertebrates favour fissured bark in sunny situations. If there is an opportunity to open up areas
around older trees it should be taken. Standing and fallen dead timber is also important, and
should be left in situ wherever possible.
It is recommended that every effort be made to conserve and extend open areas within Osier Marsh
and osiers removed from a wide edge along the sides of the path to encourage a flower-rich wetland
edge. This would be an extremely valuable resource for the insect fauna, and crucial to adults of
species such as the Musk Beetle Aromia moschata.
There are valuable open marshy habitats at the southern end of the Osier Marsh area. Some scrub
control is likely to be needed to maintain these areas. Drier areas nearby with scrub and mature
trees could usefully be cleared to expose more open habitat.
The raised gravelly areas around the western PFA pond provide valuable sparsely vegetated ground
and open habitat, and will require some disturbance management in the future to retain their current
interest.
Where Viper's-bugloss Echium vulgare is growing along the old concrete path at the northeastern
end of the Osier Marsh area, it is suggested that the path be made up with crushed limestone or
concrete to encourage plants like Echium and Carrot - the old concrete path is an unnatural feature
anyway, so it would not be out of keeping with the history of the site.
Hedgerows and field margins
It is recommended the hedges are allowed to grow irregularly into the field edge to broaden their
profile. They will become more important as invertebrate resources if their edge is 'scalloped' to
provide sheltered scrub edge. The most important part of scrub is the edge where it grades into
grassland, and the maximum length of sheltered scrub edge should be created or maintained during
management (Kirby 1992, republished 2001). The arabic field edges might become more important
forage resources if they are sown with species such as Red Clover, Fodder Vetch and Carrot.
Acknowledgements
The Lee Valley Regional Authority commissioned the survey and the first author is grateful them
for the opportunity to survey this interesting site. Survey material was identified by the first author
apart from the following: Del Smith identified the flies other than some hoverflies and Larger
Brachycera, and Dr Peter Kirby and Dr Peter Hammond identified the Hemiptera and Coleoptera
respectively
Essex Naturalist (New Series) 21 (2004)
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