THE LICHEN FLORA OF THE BASILDON AREA 139
The Lichen Flora of the Basildon Area
By P. M. Earland-Bennett
Bankfield Museum, Boothtown Road, Halifax, HX3 6HG
Introduction
Between 1971 and 1974 a study of the lichens of the Basildon area was
undertaken by Mr and Mrs S. J. Harding and myself. The area studied
(Figure 1) largely corresponds to the Urban District of Basildon, in south
Essex (Basildon town centre being 47 km from London and 19 km from
Southend). Basildon Urban District covers over 100 square km and
incorporates the towns of Basildon, Billericay and Wickford and a number
of villages. The area studied was extended northwards to include Galley-
wood Common and Thrift Wood, Bicknacre.
The study was by no means exhaustive, and several old churchyards are
still in need of careful study. Nevertheless, 72 taxa were recorded, although
many specimens were small and stunted and several records were re-
presented by only one or two specimens. Such a 'relict' status is indicative
of an area which has been subjected to high levels of air pollution over a
period of time.
The aim of this paper is to present an analysis of the lichen flora based
on the records made during the 1971-74 survey. However, comparisons
can be made with other areas in Essex peripheral to London, for which
there are detailed records of the number of lichen species dating back to
pre-industrial revolution times e.g. Epping Forest. Of the 120 taxa (118 of
which were epiphytic species) recorded by the Rev. J. M. Crombie from
1865-68, only 28 (epiphytes only) could be found in 1969-70, and most of
these in the north-eastern parts of the forest, furthermost from London
(Hawksworth et al., 1973). Only 20 epiphytes have been found in the
Basildon area, and most of these are rare and occur mainly in the extreme
northern part of the area. Undoubtedly many species which once grew
here (especially epiphytes) have become extinct and some others are on the
verge of extinction at the present time.
The sulphur dioxide component of the air has been proven to be the
main, nationwide phytotoxicant (cf. Ferry et al., 1973), although emissions
from car exhausts, other industrial gaseous and particulate matter, and the
excessive use of agricultural chemicals and fertilizers, are increasingly
detracting from the survival potential of our lichen flora. Since the early
days of the industrial revolution it has been domestic and industrial
emissions of sulphur dioxide (from the combustion of coal and oil) which
have had the most deleterious effect on the lichen flora. However, with
smoke control the low level (i.e. near to the ground) domestic emissions
showed a marked decrease for a number of years, although this is now
showing a pattern of levelling off, both nationwide and in this region. Mean