The Essex Naturalist
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and the western edges of Orsett Golf Course (Mucking Heath) are therefore
extremely important.
Significant nature conservation interest at a site normally takes a very long
time to develop, especially when surrounding habitats are already destroyed or
degraded, but with enough time "Brown Field" sites can develop important ant
communities. At an old waste disposal site on former Saltmarsh and grazing
marsh at Goshams Farm between Tilbury and East Tilbury it is highly probable
that tipping ceased in 1958 when a change in ownership occurred and there has
been no further development of the site since then. The existing cattle grazed
vegetation has developed on a poor soil contaminated with relatively high levels
of Copper and Zinc, and these factors have promoted the appearance of an
interesting flora such as the abundance of White Horehound and
Houndstongue. The ant Myrmica bessarabica which occurs in Essex in a variety
of old coastal habitats providing thermophilic conditions is present in
abundance on the sparsely vegetated and species-rich grassland areas that have
developed at the site, together with other species favouring open conditions
such as Ponera coarctata and Formica cunicularia.
The importance of old silt and PFA (pulverised fly ash) lagoons for
invertebrates is becoming increasingly apparent. Silt lagoons at East Tilbury and
Rainham Marshes develop Saltmarsh communities that gradually become replaced
by sand-dune and flower-rich ruderal communities as the lagoons dry out. Both
have both developed important invertebrate and aculeate Hymenoptera faunas,
with numerous Nationally Rare and Scarce species. At West Thurrock and
Barking there are areas of old pulverised fly ash (PFA) lagoons over former grazing
marsh with interesting plant communities and important invertebrate faunas.
There are remnant grazing marsh dykes, marshy areas of Phragmites and sedge,
banks of sparsely vegetated PFA, areas of ruderal flower-rich vegetation and scrub.
The communities that have developed on the PFA substrate at Barking are
very different to those to be found at West Thurrock, where a Saltmarsh flora
grades into drier grassland and scrub with many calcicole plants dominating. At
Barking there are areas of fen and some quite remarkable dune-like formations
resulting from weathered and compacted PFA. The RDB3 ant Myrmica
bessarabica occurs on sparsely vegetated areas of PFA at the site and this year has
seen the quite astonishing discovery of the jumping spider Synageles venator and
chrysid wasp Cleptes nitidulus, both rare Nationally Scarce Notable A species
normally associated with dune systems (see Recorder Reports for spiders and
aculeate Hymenoptera). Even limited fieldwork has shown the site to have
numerous other nationally rare and scarce species, with a very high Invertebrate
Index and Species Quality Index. Most of the Barking Levels have already been
developed for housing and this site will also soon be totally destroyed by more
housing development, leaving virtually no habitats of significant nature
conservation interest in the area. The loss of biodiversity in this area of south-
west Essex will be huge and will further fragment the nationally important
invertebrate populations present in the East Thames Corridor.