Lichens and industrial pollution - Ecology of Industrial Pollution - page 46

London and other cities have provided valuable refuges for certain lichen
species, including during conditions of high pollution (Laundon 1967 , 1970 ,
1973 ; Gilbert 1990 ). New lichen species to science have been found in London
and designated as 'type material' (i.e., the original specimen used to describe
the species). In London, All Saint's churchyard in Fulham is the type locality
of Lepraria eburnea, and Blackheath is the type locality for Vezdaea leprosa
(Waterfield 2002 ). The latter species is considered a stress-tolerant 'ruderal'
(Gilbert 1990 , 1992 ). Stress-tolerant ruderals occur in habitats in which the
character of the vegetation is determined by the coincidence of moderate
intensities of stress and disturbance (Grime 1979 ). London and other cities also
provide habitats for rare lichen species. At Kew Gardens, beautiful yellow
patches of the rare, Red Data Book species Cyphelium notarisii were found
colonising garden benches near the Palm house in 1998 and were still present
in 2005 ( James & Wolseley 2005 ).
Air pollution was reported from cities as early as 1273, when the burning of
coal in London was prohibited as being 'prejudicial to health' (Laundon 1973 ).
Laundon suggests it is likely that air pollution was already having some effect
on lichens at that time. Needless to say, medieval legislation was ineffective.
By the seventeenth century, ever increasing coal combustion in London led
to a serious and growing problem and the first records of damage to vegetation
were fascinatingly portrayed by the English diarist John Evelyn in 1661 in
'Fumifugium: or the inconvenience of the aer and smoake of London
dissipated' (Bell & Treshow 2002 ). The first known lichen records to be pub-
lished for London were those of James Petiver who recorded Cladonia coccifera
(a red-fruited 'pixie cup' lichen) from Putney Heath before 1695. This species
was noted by Laundon as 'gratifyingly being present nearly 300 years later'
(Laundon 1967 ). Cladonia gracilis, collected from Hampstead Heath on 7 March
1696/7 (probably by Reverend Adam Buddle), is now in the Sloane Herbarium of
the British Museum (Natural History) (Hawksworth & Seaward 1977 ). The Heath
is the type locality of Cladonia peziziformis, a Biodiversity Action Plan species no
longer found there. The type specimen collected by Dillenius is in the Sherard
Herbarium at Oxford (Waterfield 2002 ). Cladonia species occur mainly on acidic,
humus-rich substrata (Purvis et al. 1992 ) and are considered as 'acidophytes'
(species which prefer acidic habitats) (Van Herk 1999 ; Sutton et al. 2008 ). They
thrive near point pollution sources such as smelters emitting SO 2 and metal
particulates (Mikhailova & Vorobeichik 1995 ; Williamson et al. 1996 ; Purvis
et al. 2004 ; Purvis & Pawlik-Skowro´ska 2008 ). Evidence suggests these species
in Britain are generally declining in recent years although quantitative data
are lacking (Coppins et al. 2002 ).
The most intensively studied woodland lichen assemblage in relation to atmos-
pheric conditions and ecological continuity is Epping Forest, lying northeast
of London (Hawksworth 1973a ; Laundon 1973 ; Hawksworth & McManus 1992 ;