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The Essex Naturalist
A wildlife corridor will only be useful to those invertebrates that can find
their habitat requirements within it. Migration along the corridor will depend
on these habitat requirements being available at a number of places along the
corridor close enough to allow natural movement. This is evidently particularly
important when suitable habitats are not available outside the corridor because
the surroundings are developed for industry, housing or intensive agriculture.
The value of wildlife corridors is therefore likely to be limited by the habitats
available within it. A variety of habitats will help species to survive and move
on as natural succession makes one part of the corridor unsuitable. But even
when the corridor contains a variety of habitats, succession will inevitably take
place and open areas will soon disappear. Grassland areas will scrub up, their
flowers will disappear and open sunny areas will become shaded out. Once this
happens the value of the corridor to many invertebrates will be lost. Wildlife
corridors are usually very narrow strips of land and open areas will disappear
much more quickly than in most other wildlife sites.
Management will be needed to maintain the variety of habitats and this has
far-reaching implications for wildlife trusts and local authorities. Maintaining
the value of many corridors is likely to be difficult because the rate of succession
will make frequent management work necessary and access along the length of
the corridor may well be difficult. The problem is compounded by the current
fashion for tree planting in virtually any open space and roadside embankment,
the subsequent scrub and tree development destroying valuable open habitats.
It is therefore very important to be realistic about the value of wildlife
corridors. Too much importance should not be assigned to them in wildlife
planning and Local Plans without careful assessment and a recognition of their
limited value and dependence on management. The future of nature
conservation within the county depends not only on the identification and
protection of sites of nature conservation importance but also on the survival
and adequate management of sufficient intervening habitats to maintain variety.
Ecological significance of ants
Ants are important predators of small arthropods and also tend aphids and
coccids for their honeydew. Most ant species are destroyed by cultivation and
cannot survive in arable land although one or two species may be found in the
adjacent field edges and hedgerows. However some ants occasionally have local
importance because of their tending and protection of aphid species
(Collingwood, 1979).
Some species can form large populations and in old pastures ant mounds
develop a characteristic flora of herbs, grasses and moss that contrasts with the
surrounding habitat (Collingwood, 1979). In Essex these mounds provide a very
different and important microhabitat for example in grazing marsh grassland for
more thermophilic species of invertebrate.