Resurvey of the Corticolous Lichen flora of Epping Forest
than Epping which has a current NIEC value of zero. It should however be noted that the NIEC
value alone should not be used to assess the conservation status of woodlands where exposure to
high pollution levels has severely reduced diversity as in this case.
A review of the combined historical records for Epping, over two centuries gives an NIEC Index
value of 11. So, although Epping is well studied and is an extremely important site at a European
level, it has never been a site of high conservation interest for its lichens. The interest here lies in
the pioneering communities now being established.
The communities in the more sheltered inner areas of Epping Forest are typical of anew pioneering
community with the notable exception of Graphis and Pertusaria species, which have not returned.
However, the abundance of Dimerella pineti and the presence of Chaenotheca ferruginea, Fuscidea
lightfootii, Gyalideopsis anastomosans, Platismatia glauca, Schismatomma decolorans,
Hypocenomyce scalaris and the appearance of Opegrapha ochrocheila in the Forest suggests that
an interesting non-nitrophile woodland flora is developing, particularly in central parts. It remains
to be seen how far this newly established element of the woodland lichen flora is able to compete
with the more ubiquitous, rapidly colonising nitrophile urban communities.
Highest diversity for over a century, coupled with the appearance of many pioneering woodland
species, provides evidence of a sustained recovery of the lichen flora under conditions of low
sulphur dioxide and increasing nutrient enrichment. This trend is accompanied by a reduction in
frequency and abundance of Lecanora conizaeiodes, Hypogymnia physodes, Cladonia spp. and
the loss of Foraminella ambigua, and Parmelia saxatilis, species considered to prefer a more acidic
environment (Hawksworth 1970, Bates et al. 2001).
Communities occurring near to roads, at car parks throughout the forest, and at sites closest to
London include Bacidia delicata, Candelariella reflexa, Flavoparmelia soredians, Lecanora
symmicta, Lecanora confusa, Physcia aipolia, Punctelia subrudecta and Xanthoria polycarpa, all
now common urban species and tolerant of, if not encouraged by, high concentrations of particulate
matter, oxides of nitrogen and other vehicle emissions.
Acknowledgements
This study was commissioned by the Epping Forest Management Team, Corporation of London
and is part of a programme of work arising through collaboration established by the Air Pollution
Research in London (APRIL) network chaired by Professor Helen ApSimon of Imperial College
London.
References/Bibliography
BATES, J.W., BELL, J.N.B., MASSARA, A.C., (2001). Loss of Lecanora conizaeoides and other
fluctuations of epiphytes on oak in S.E. England over 21 years with declining sulphur dioxide
concentrations. Atmospheric Environment 35: 2557-2568.
BOREHAM. S. (1993) Changes in the lichen flora on birch Betula pendula in northern Epping Forest. The
London Naturalist, 72.
CROMBIE, J.M.. (1885) On the lichen flora of Epping Forest, and the causes affecting its recent diminution.
Trans. Essex Field Club 4: 54-75.
CROMBIE, J.M.. (1894) A monograph of Lichens Found in Britain, 1. London.
Essex Naturalist (New Series) 20 (2003)
75